Technical Data, Measures and Adjusting Values [oono. Change: marked with x 00-0 OO [| omeae 7 66914 626995, <9 asic OM 621 919 636937 Type or design model ea eaeee 836952 638.999 636992 696997 |. g0De | x190De 19D. | Land 636904 1900 |xO319D intoke valve | 020 015 Valve clearance with cold engine oom exhaust valve x025 ox | 035 ‘Compression pressure with normal operating temperature [cooling water 70-809) and ot 200-250 "pm. normal 21-28 oto 2.26 of minimum V7 o10 1Bot0 26° BTDC be engines fo fk f crankshaft when installing the injection pump in Him dave 260 BTDC feed begin position (see Job No. 00-6) s° BTDC ‘nett ta Check with overtiow pipe | Stet pat“! Meade ane? it fon Ist pump element Sree on Feed begin of injection pump (see Job No. 00-6) (Check with pre-stroke measuring device ot 1st pump element 1740.1 mm 1s from BDC I + Any high speed Diese! knock Cload-knock) in OM 6% engines without injection timing device con be elini- nated by advancing the cronkshalt postion with respect fo he feed begin of The injection pump from 22° fo BTS, provided nt the iling nock i not excessive. The feed begin on fork lit engines is adjusted fo 26° BTDC in order to prevent heavy fumes ot lower speeds. | This wl oso sightiy improve torque ov lower speed, but he output et speeds cbove 2000 rpm: decrecses progressively in elaion To lhe 32° BYDC edjuslment | Check and adjust the feed begin of the injection pump according to the overflow method or with the help | ofthe pre-stroke measuring device. taling 550-<00p:m. | 700-800 cpm T weoopeocim | (eters pose Max. speed, unloaded | and fall. pages) 0-2) ° | Feed pressure of feed pump, min [[2 Change May 65— Workshop Manvel OM Diesel Engines_] 0-0/1Timing for Test Measurements with a Test Valve Clearance of 0.4 mm: Camshaft tntet Exhoust Test Valve Medel Version area Part No. edu gzens | closes | opens | closes | ‘Eyhows BIDC ABDC ‘BBDC ATO Li! 1e1 051 0301 ew | ae | ae * | ined in th nce pe 2654, ‘sand me noting wih he engin od No. hast cade al over of he type 691, 9, 30,2, | Lomas 11 051 001 ear | aay | ear | seo ined ine sane 6 The aie Ob mm 621 0500101 ne we | ea | pay ined in he egies ys 2.710 * 621 0500201) OME2! | snd inh engines pee naan ane x 62105112017) Wed aay oe * inte in he egies 0 Sho nae 10 ond rom engin Ni, ainctonne Bineosss 1) This comshoft is marked by the number “OV” at is rear face. 2) This comshalt is marked by the number "02" ofits rear face. 2) This camshaft is marked bythe number "12" at its ear face. 0-0/2Job No. 00-1 Model | omess | omen Crankshaft beering bolts Bmkg 9 mkg elongation 0.1 mm Big end bolts J in mkg 375 mkg . light metal head 7 mks coh moral head with cold engine Hts 8mkg ylindar heed bolts’ * a oe ee _| light metal head - mk Catt cal hee with warm engine sno 8 mkg Rocker orm nuts and necked-down bolts for rocker arm bracket mounting 2mkg | 375 mkg Glow plugs Simkg Threaded rng for prechamber mounting in cylinder head [tS mig Union nut for mounting nozzle in nozzle holder 7 7-8mkg Nozile holder in cylinder head 7-8mkg Re fo gdeotr on The wosla holy Gowferhol woz fader when i Pipe, comecions for ijecion Ths on We Walon pump [presre volve yor | + Bol of clamping iw locks for pipe connections of injection pump asmks Union aut for injection lines 25 mig inerrant ces eraaaaanss nig |s560atg) Temata a Oe cares 7 7 aren conch Tg Normal bolt for mounting of light metal pulley on crankshaft (see Fig. 03-1/2) 12mkg, a x Connecting bolt or air nozzle with auxiliary venturi tube in valve socket | - 1.2-1.5 mkg "ae sure to obra, he sequence ond gradual, tgherig of jhe clinayr aod bolle in, order jo. avoid diotin of the heed (ve Fi Geafi"oad Pty Se oy af aqesas ee {ere Tighten the thar Bosh read RL or O by oncne Sf mrss si an operation of hoe wih essing wale apa 4 fe boning loa for neaddown bat 12K 62120071 53 Yo 60 mhg and fr saed-doan bol 10K 1206510671 45 to Fig. 00-1/1 Tightening of cylinder head bolts sen oP Mosel OM 636 Tightenin 1a toraue Aik oF Ind ora ime 1s torque {0h check Torque with warm engine T= Change Dee. 62 Workshop Manuel OM Die Engines Fig. 0-1/2 cf cylinder head bolts Model OM 621 ania canis ams 0041Adjusting Valve Clearance The exact adjustment of the valve clearance is especially importont for the smooth running and performance of an engine. It has to be observed on the engine Model OM 636, that the inlet valve clearance is greater than the exhaust valve clearance. This is given by the design through the different length of the rocker arms. Mistakes by exchange have to be avoided by all means during the adjusting of the valve clearance (position of inlet and exhaust valves see Figure 00-3/2) If the valve clearance is too small, the valves no longer close satisfactorily and burn out. Too large valve clearance causes valve noises. Furthermore, incorrect valve clearance causes changes in timing and reduction of engine power output. A.OM 636 1. Remove air filter and cylinder head cover. the piston of the Ist cylinder to ignition dead center. The piston of the 2. Check torque of cylinder head bolts and hex nuts for fixing rocker brackets, tighten according to instructions if necessary (see Job No, 00-1). Ist cylinder is at ignition dead center if the inlet as well as the exhaust valve is closed. At the same time the rockers 1 cond 2 are released and the valves 7 and 8 of the 4th cylinder are overlapping, meaning the exhaust valve closes and the inlet valve opens. The crankshaft is turned at the fixing screw (8), with which the pulley is attached to the crankshaft, by using a 27 mm wide box spanner with ratchet or a cranked | double box wrench (see Figure 00-3/1) In vehicles the crankshaft can also be . s fumed by shifting into 4th gear and pushing the vehicle. A 7 The ignition dead center of the other t 3 cylinders is adjusted in the same way. “= Note: To eliminate mistakes we recommend to proceed with the valve clearance ad- justment in the same order os the fring order. Figure 00-3/1 The firing order is 1-3-4-2 1 Ting hosing cover 8 Horoaen sew a otieneceone eae 4, Measure the valve clearance of the 4 Genta Bo an respective cylinder with a feeler gauge or 4 Spocer TDC marking ond scale to tolerance gauge with a thickness of the 78pm water BISON a ed specified valve clearance (see Job 00-0) between valve stem end and rocker (see Figure 0-3/3}. 0-3/1Location of Inlet and Exhaust Valves << _ Direction of driving VstCyl, 2nd Cyl. Bed Cyl. Ath Cyl El De EI Le eo 600 00 00 Figure 00-3/2 If the valve clearance is too small or 100 large, loosen the hex nut of the respective ball-head bolt with the combination wrench Part No. 0005896409 and ad- just ball-head bolt by screwing in or out (see Figure 00-3/3), in such a way thet after the tightening of the hex nut the specified clearance is obtained between the valve stem end and the rocker. Note: During tightening of hex nut the ball- head bolt must be held fixed and ofter- wards the valve clearance has to be checked again. It should only be just possible to move the tolerance gauge between the rocker and the valve stem end. During the measuring the tolerance gauge should not be tilted, it should possibly be inserted vertically to the valve stem. If the tolerance gouge is jamming, move rocker sidewards before adjusting valve clearonce. In many cases you will observe that the rocker was only tilted. 0-3/2 Figure 00-3/3 1 Combination Wrench Por, No, 0058 607 5. Check ogein with feeler gauge the ad- iustment of the individual valve clearances and readjust if necessary. 6, Remount cylinder head cover. Make sure that the gasket is properly seated. The cover should not be screwed down too thightly, because it can sag and force out the rubber gasket. 7. Remount air filter, operate engine and check cylinder head cover for leaks at the contact surface,B. OM 621 The valve clearance should be checked and adjusted with cold engine only. 1. Remove air filter and cylinder head cover. 2. Check tightening torque of the cylinder head bolts and the necked-down bolts for mounting of the rocker arm brackets, if necessary, tighten as specified (see Job No. 00-i). 3. Set the cam of the respective valve in such a way that the base circle of the cam is facing the sliding surface of the rocker arm (see fig. 00-3/4), Figure 0-3/4 8 Hex at 9 Valve soring retinar wise ng aoasr 10 Valve spring 1 Rubber seat rng 12 Valve sem, 13 Vole vide 2 Groote involv sam 1 Nedtod- down be 2 Reder rm shat 5 Rocker orm bracket § Comat 7 Cap rut 4. Use a feeler gauge to measure the valve clearance. The feeler gauge (15) must be moved between the rocker arm (6) and the cap nut (7) with slight resistance (see fig. 0-3/4 and 0-3/5). 7. Figure 0-3/5 6 fodker orm 15 fooler gave with holder tine a Bes IS Letting ane 9 Nee arn renga rerluing of aap 14 Special wren, port No. wren, port No eS i ASN ve i 589 01 Ob for loosening, 3 valve spring ‘A Sand tightening Hosta BY For correction of the valve clearance, use special wrench (14) fo loosen the hex. nut (8) on the valve; to do this, counterhold the cap nut (7) with the help of special wrench (16). Then adjust the speci clearance {see Job No. 00-0) by resetting the cop nut (7) using special wrench (16). Should, during the adjusting work, the valve turn with the cap nut, do not fail to retain the valve on the hexagon of the valve spring retainer (9) using special wrench (17). After adjustment of the cap nt (7), secure some by tightening the hex. nut (8) and then check the valve clearance ‘again (see fig. 00-3/4 and 0-3/5). ;. Mount the cylinder head cover, observing the correct position of the rubber seal. IF necessary, replace the seal rings for the mounting screws. Further check to see whether the wire cable (18) moves freely in the slot of the stop angle on the toggle lever (24) when depressing the accelerator pedal (see fig 00-11/2). Operate the engine ond check the cylinder head cover for leaks. 00-3/3Che 1g Injection Nozzles and Glow Plugs If the engine vibrates and/or runs out-of-round or suddenly shows continuous load combustion noises (knocking) or drops considerably in power output, these troubles can be caused by fouled and sticking needles and/or too low opening pressure of the nozzle, faulty pre-combustion chomber or leaking vacuum system andjor leaky diaphragm. If you have one of these troubles conduct the following checks and/or operations: ©) Pre-heating Check: Pre-heat; if the glow control light on the instrument panel is illuminated too brightly or not at all, then check pre-heating system and determine which glow plug is defective. To do this, succesively bridge and/or draw sparks at the individual terminals and turn the starting h to position 1 ct the some time (see Figure 15-32/1 and Job No. 15-33) Note: A defective glow plug can be an indication that the corresponding nozzle is not in order or that the pre-combustion chamber has become faulty. 2. Replace faulty glow plug and remove corresponding injection nozzle and pre-combustion chamber, clean injection nozzle and replace pre-combustion chamber if necessary (see Job No, 01-1 and Job No, 07-18} 3. Testing glow plugs (see Job No. 15-32) b) Observation of Exhaust Gases: While stationary, open throttle fully ond/or portly for o short period and observe the exhaust gas jet ond watch out for noises (rumble) at the mouth of the exhaust Irregular black clouds are often on indication that one or several nozzles function irregularly. ‘An increase of the injection volume can also be caused by an extensive reduction of the nozzle pressure and/or through normal wear or leaky vacuum system or injection pump diaphragm. Remove injection nozzles, clean and test them (see Job No. 07-17 and Job No. 07-18). (Further reference is made to Job No. 0-10, Page 0-10/4, Engine is sooting heavily.) Check for leaks at jection pump governor. IF on irregular noise (rumble) is observed at the mouth of the exhaust, then one cylinder mis fires (see following point c, Working and Sound Test). ¢) Running and Sound Test: 1. During idling and increased idling loosen the cap nuts of the individual injection lines at the injection pump successively by half a turn and tighten again and observe smooth running and sound of engine. 2. IF there are no changes in the smooth running and sound of the engine while the cap nuts are loosened, it is an indication for the fact that the corresponding nozzle can be defective and has to be removed and checked (see Job No. 07-17, and Job No. 07-18). 3. If the engine runs out-of-round w tion nozzle is faultless. fone cap nut is loosened, then the corresponding injec- Note: If the injection nozzles are removed, the pre-combustion chambers must also be visually checked (see Job No. 01-1), In engines which knock heavily or emit dense exhaust smoke injection nozzles with a somewhat larger throttle gap should possibly be installed (see Job No, 07-0 and 07-18} 0-4/1Testing Compression Pressure Change: Item 6 was changed and nate on page 00-5/2 added Job No. 00-5 In the event of complaints concerning an engine, e.g. poor performance, poor starting ability, high oil consumption, extensive smoking of engine, running out-of-round, etc., the compression pressure should be tested on top of other checks. The compression pressure gives an indication on the condi tion of the valves and pistons. The compression test should only be conducted while the engine is warm. With engine cold the obtained values are unreliable, because they do not correspond to operating conditions. The compression pressure is measured with a pressure gauge or the generally used compression tester. 1. Check valve clearance, adjust if necessary (see Job No. 00-3}. 2, Bring engine to normal operating tem- perature (cooling water temperature 70 to 80° C) 3, Disconnect power leads and remove glow plugs with the Spork Plug Wrench Part No, 136 5890336 or Glow Plug Wrench Part No. 136 589 03 09. 4, Crank engine several times with the star ter, so that possible oil carbon residues and soot are forced out. This is advisable, because the soot might clog the com- pression tester. 5. Screw adapter (1) to glow plug hole of the cylinder to be tested. Tighten adapter well to obtain proper sealing. With Model OM 621, also connect the angular piece part No. 000 587.0090 with the union nut to the connection fitting (1), when measur- ing the 2nd and 3rd cylinder. Then connect the compression pressure recorder (3) with hose (2) to the connection fitting (1) and the angular piece, resp. (Fig. 00-5/1). 6. For testing, turn engine with starter 8 times. Fully open throttle butterfly at the same time 0 obtain good cylinder charge {throttle wide open} Figure 00-5/1 7. Test with this method all 4 cylinders in the order 1 through 4. Set the test diagram in the compression tester to the new working position corresponding to the cylinder to be tested. During the individual tests, maintain similar period of cranking. By using the Compression Tester Part No. 000 589 69 21 the average compression pressure reached is approx. 22 to 23 atm, 1 Change Dee. 62 Workshop Manual OM Diesel EnginesThe test results of the individual cylinders Fahrzeug should not deviate more than 2 atm, from ee each other (Figure 00-512) Pree ae ae If the deviation is larger for one cylinder, then it is practicable to conduct a second test. A compression pressure of only 17 atm. or less indicates that valves, pistons or piston rings are in need of repair. If considerably lower pressures are registered for two ad- jacent cylinders as compared to the others, then the cylinder head gasket between these two cylinders is leaking os a rule. Figure 00-5/2 fo Note: The engines of types 621.912 and 913 are equipped with a valve turning device for inlet ‘and exhaust valve, which provides for longer life of the valves. If the valve turning device does not function properly, a drop in compression pressure will occur, with the result of leaky valves. If a drop in compression pressure is noticed (rated value of 20 to 23 atti 284-327 psi drops to 13 to 15 all 185-213 psi) it will be sufficient to install only o new valve turning device (6) for each of the inlet and exhaust valve in the cylinder in which a drop of compres- sion pressure prevails. (Refer to Fig. 01-6/6,) The valves ore sealed by turning the device and the compression pressure will rise again. In order to make double sure, « second check of compression pressure after approx. 3000 km. (2000 miles) should be performed. If the result is not fully satisfying, remove cylinder head ‘ond check valves, valve seats, pistons, piston rings and cylinder paths for wear, and repair. 0-5/2Checking and Adjusting of Feed Begin 00-6 The exact adjustment of the feed begin is of decisive importance for the power output and the sotisfactory operation of the engine. The spcified adjustment data of the feed begin for vehicles of the different types and fields of application (see Job No. 00-0) If the engine is equipped with an injection timing device, the feed begin is advanced in relation to the engine speed between 26 deg (basic adjustment) and 38 deg BIDC ot 3500 rpm (also see Job No. 07-4, VI,, Description of the Injection Timing Device), A. OM 636 |. Checking the Markings for Top Dead Center (OT) and Feed Begin (FB) Since the engines are equipped with different and differently marked flywheels or a flywheel could be mounted wrongly, the markings for top dead center ond the feed begin must be checked before the checking and adjusting of the feed begin, to make absolutely sure, that the piston of the Ist cylinder is actually at top dead center ond feed begin respectively. Only the correct and exact adjustment of the feed begin guarantees the full power output and the smooth and safisfactory operction of the engine. The engines of all types of the model OM 636 are therefore now furnished with a timing needle and with a TDC-marking and markings at 20 deg, 25 deg and 30 deg before top dead center on the belt pulley of the crankshaft for the easy checking and adjusting of the feed begin (see Figure 0-6/2). With this arrangement a checking of the mar possible, even while installed. is on engines of the recent production is always On on: 1s of the former produ jes to check the markings: ©) For installed or removed engines: through the marking on the belt pulley and the timing needle at the timing housing cover (see Figure 00-6/1). b) For installed or removed engines with attached clutch housing: through the marking on the flywheel and the inspection hole in the clutch housing (see Figure 00-6/4 and 00-65}. J Only for removed engine without clutch housing: through the marking at the flywheel (the mark- ings are advanced 50 deg in relation to vertical) and the timing needle (see Figure 00-6/6).. 4) For removed engine without clutch housing: through the marking at the flywheel and the sctewed-on hexagon screw (see Figure 0-6/7}. e) If there is no marking or the accuracy of the marking is doubiful, make marking for feed begin (see Section IV) 0-6/1719-00 Table of the Provided Markings at the Engines of the forme roduction, Model OM 636 Marking Marking Marking Meiking (Fig. 0-61), (Fig.00-6/4 and 00-85) (Fig. 00-6/6 and 00-6/9 A and B) Fig. 00-6/7 and 0-4/3 C) Belt PlleyPor-N. 181 20017 05 Timing Needle Port-No. 6360150271 (see Figure 00-41) Flywheel PartNo Type identification oF the engines see marking ond jentifcation of cond d cond Figure 00-6/4 cond Figure 00-6/5 ‘An inspection hole in’ cluteh housing Hog he engines wil the type Wontieaton je ee. | 990 | as 636, a6 V 934 ne a9 900 331 904 636.030 0205, (s00 Figure 00-6/6 and 00-6/3 A and 8) 90 120 a6 180 38 19 319 3h eseoiz_| 240 331 260 oe 200, 20 0 360 clo the waines of the type 91710 version A, B, C, D, F, Q, U, V, W, X, ¥ and Z. For the engines of the type identification 1, Mand P the fywheol is sent by the tame te Botbtonbent 7 Tho engines of the type identification will be supplied without fywheel By the Daimler-Benz Plant Untertverkheim (040 ondfor/S essai {90 626917/12 {626:917/0 of the versions 25 = 370 = Wandior 023 andfor /33 2 andlor /23 636.917— | 222 andlor [29 |B = 69603001 05 (s0e Figure 00-6/7 and 00-6/3 C) 3 om 3 % al 3 u (32 270 ue 626. | $8 assur. 2 cassrny 18 |3 Fe " mo 38 z 3 2 91710 version E, G, H, K, Ly N, ©, R, $ ond T.Note: The engines of the type 636.917/5 and) or 917-040, 917/12, 917/31 and/or 917-252, 917-272 and the engines of the type 917/0 version J, M, and P are equipped with flywheels (for hydraulic clutches) produced outside our plants. If the flywheels of these engines are without marking for feed begin determine the latter and mark flywheel or pulley accordingly. Figure 00-61 Belt pulley with TDC-marking (OT) ond scale for the adjusting of the feed begin, 2 0Cmerking 10D Checking on installed engines: 1. Bring the piston of the Ist cylinder to ignition dead center (see Job No. 00-3, Pos. 3). 2. Check this position af the pulley or at the flywheel through the inspection hole in the clutch housing The timing needle must point to the TDC- marking on the pulley (see Figure 00-6/1 and 00-6/2} or the marking OIT andjor IOTI on the flywheel depending on design of flywheel must be visible in the approxi- mate center of the inspection hole in the clutch housing (see Figure 0-6/4 and 0-6/5) Figure 0-6/2 Belt pulley with TDC-marking (OT) and scale with Timing Needle Port No. 6360320015, Note: On the flywheel Part No. 6360300205 the markings for feed begin and top dead center were advanced 50 deg in relation to vertical, in order to be able to observe the markings through an inspection hole in the clutch housing while the engine is installed (see Figure 00-6/3 and 00-6/4), On a part of the engines of the type 636.930, 919, and 934 the inspection hole is plugged with the screw Part No. 120 2510071 to keep out dirt. The screw also serves to ventilate the clutch housing (see Figure 0-6/4). 0-6/3Figure 00-6/3 ‘The Figure 00-8/3 shows the merkings of the Aywhes! Part No, 636 0300205 "andthe flywheel Port No. 638 68000 05 ‘A-& Merings of he hywhes! S600 8G forer vrton OT = top dead center FB = food begin BTOC 8 a Morkinge ofthe Ara GEOG presen vorion OT = top decd canter BP & feed begin 6° STDC for engines ih ngasion tning device Gnd rains Yor Fok ie {5 = fea begin BTOC for aires vttoutnjton sing Senco C= Morkings ofthe twhoot wean (OF = t99 decd center = food begin 0 BTOC (860 Figure 02.47) Figure 00-6/4 Figure, 00-64 shows the TDC-marking (OT) os seen thBugh'the mspecion Rele of acta hoosg of Sor Voile Model "600 type a0) 0-6/4 ‘igure 00-6/5 Figure 00-4 shows the, merking OT (I) as seen though tho inspction helen ine dutch hosting of our “Bhimog! voile type 35918, Checking removed engines: 1. Bring the piston of the Ist cylinder to igniton dead center (see Job No. 00-3, Pos. 3). 2. Check this position at the pulley (see Fig- ure 00-6/1 and 00-6/2) or at the fly- wheel after attaching the timing needle Part No, 636 5890023 to the dowel pin (see Figure 00-6/6) or at the flywheel after screwing on a hexagon screw (see Figure 00-6/7).. The timing needle must point to the OT- marking on the belt pulley (see Figure 0-6/1) or the Timing Needle Part No. 6365890023 ‘must point to the OT-marking on the fly- whee! (see Figure 00-6/6) or the hexagon screw must be located be- tween the lines marked wit [OT] (see Figure 0-6/7). TheFigure 00-6/6 shows the Timing Needle Part No. 636.589.0023 which is fixed by the dowel pin; the marking FB = feed begin 32 deg before top dead center ond the marking OT = top dead center.Figure 00-6/6 Flywheel Pact No, 636 0300205 OT = top dood comer feed toon ‘injection The arings on hs Rel ere esroncd 5 dog ——— ta M5 890 Figure 0-6/7 Flywheel Part No, 636003001 05 Inthe photogroph the crarksott is ot feed bogin 30 dog before top dood canter (OF = top dood contr and Be begin St" BIO ° hres I Checking Feed Begin with the Overflow Method on Removed or Installed Engines 1. Set the piston of the 1st cylinder to ignition dead center (see Job No. 00-3, Pos. 3) nd check morking according to Job No. 00-6, Pos. I. 2. Remove the glow plug of the Ist cylinder, turn the crankshaft approximately 50 deg in the opposite direction, so that the crank- shaft is approx. 50 deg BTDC and approx. 20 deg before feed begin. The gear backlash is eliminated or the chain is kept tensioned by the fact that the crankshaft is again turned in the correct sense of rotation between 50 deg BTDC cand the feed begin. This is the reason why the crankshaft should by all means be turned back to approx. 50 deg BTDC and not only just to feed begin. Note: On engines with injection timing device the crankshaft must always be turned in the correct sense of rotation, so that the centrifugal weights are not forced out of their idling stop position. Therefore, turn the engine 134 revolutions in direction of rotation. Furthermore, be- fore each checking of the feed begin the injection timing device has to be checked for its idling stop position. To do this remove the lid of the timing housing cover. Then check with finger whether the centrifugal weights are in their idling stop position (see Figure 0-6/8). 0-6/5Figure 00-6/8a Engine OM 621 1 Comhottesar 4 Chain gener “Venting ie for water pune 5 Woter cin 7 Paley on eronaho 4 Color sre 12 Guide oi autor with locking wire on cylinder heod 1S Scr plug for lr sproce bering sin 14 Hox sro 6x0 16 Guide res oner 17 Pivot pn fr guide rail on eylinger head 18 Screw lug for guide spose Bearing pi 20 Inti ining device 21 Screw pug lo i pressure rei vole £2 Serew plug wih guide rail Basring pi, bottom in cylinder 24 Intermediate plate on cylinder crorkco for sartr motor Figure 0-6/8 Engine OM 636 1 Check postion of centritgal wight rollers 2 Wench ta held injection ing SoviceChango: Note on page 00-6/8 added and item 7 on page 00-6/9 extended Hold the injection timing device in the idling stop position by means of a double’ box wrench which is held in place by a long spring (see Figure 00-6/8 and 00- 6/80), to make sure that the centrifugal weights remain in the idling stop position during the adjusting of the feed begin. This device prevents the centrifugal weights from moving during the cranking of the engine even in reverse direction). Fig. 00-6/9 AcInjection pump for OM 636 engines 2 Fenton aing 4 Connacor(pesue valve holt) Fipe connection, pressure vale ond stl rng of the Mngction amp for OM il ngins (ese figs BOAT, 3. Disconnect injection line ot the pressure nipple of the Ist pump cylinder. Unscrew the pressure nipple, take out pressure valve and pressure spring (see Figure 00- 6/9). Screw the pressure nipple in again and attach the overflow tube (4) Part No. 636 589 02 23 (see Figure 00-6/10) 4, Connect fuel tank (1) Part No. 00058905 23 with injection pump, fill tank with clean fuel and open the stop cock (2) of the fuel tank (see Figure 00-6/10).. The fuel flows out of the overflow tube (see Figure 00-6/11) Fig. 00-6/11 Fig. 00-6/12 Fig. 00-6/10 lonk Port Na, 0 S805 2 wih tbe 42 567019009 1 Fost 2 Sop 8 Connacor atthe injection pump 4 Overfiow tbe Part Nov 665890223 screwed onto the pipe connector ofthe al pump spiner Note: For checking it is not imperative to con- rect the fuel tank. To do this, itis sufficient to unscrew the bleeder screw on the fuel main filter, as it is done during the bleed- ing procedure. The fuel stored will suffice to carry out one or two checks. 5. Then turn crankshaft slowly in direction of rotation until the fuel starts to drip (see Figure 00-6/12) and/or until the fuel is just about to stop dripping. Approx. 15 to 20 seconds later one additional drop may follow (see Figure 00-6/13} Fig. 00-6/13, T= Change Dee. 62 — Workshop Manual OM Diesel EnginesIn this position the pump plunger just closes the inlet dilway in the pump cylinder, that is, the plunger of the Ist cylinder of the injection pump is set to feed begin (see Figure 07~4/4), If the position of the tim: ing needle also coincides with the feed beginning marking and/or with the respec- tive number of degrees on the belt pulley or on the counterweight (see Figure 0-6/1 and 00-6/17 andjor the feed begin mark- ing on the flywheel is also located in the center of the inspection hole of the clutch housing [see Figure 00-6/4 and 00-6/5), then the feed beginning is correctly adjust- ed. If the adjustment is incorrect, then adjust feed begin (see Section Ill) again. In order to repeat the checking turn crank- shaft for exactly two revolutions in the direction of engine rotation (see Section Il, Note of item 2). Turn again slowly to- wards the end of the second revolution until the fuel just stops dripping ot the overflow tube (see Figure 00-6/11, 00-6/12 end 00-6/13}. Note:The engines of ype, 190 Db as from engine No. $21910-10-012226, ot wall ox engines of type 190 De, fend 0 319 an 190 De are equipped with an injection pump having two guiding edges, that is, the pistons of these inletion pumps have @ top at wall os a bottom. guiding edge Ove fo the Guiding edge ft the top the feed begin will that the engine will run smoother, Contrary to, the former injection pump ty spectively. Therefore, itis absolutely necessa of the control tod ie with only a single, bottom guiding edge, the these injection pumps. dependant on the postion ‘of the pitons of fhe elements, or fe relarded in the idling and partial load range of the engine with the result test 1g. of injection pumps with two guiding ed to ful load, since in this position the feed begin is constant. During thet the fo checks, detach starter and stop pulls on injection pump adjusting lever to make sure that the odjvsting fever is on full load During installation of starter and stop pulls make sure tht tnd stop switch there ls adjusting lov fale for sary running Be sure that the injection pump feed begin is mecsured ace. to the overflow safer and provider better ‘values than the capillary method. - lay of epprox.'20 mm 0.0787 In} between. the bolt and the rect portion ef the oblong ‘al. tion “Fal” (Diving of in addition, check bowden control thod, since this method is Il Adjusting Feed Begin with the Overflow Method on Removed and Installed Engines 1. Conduct operations described in Section II 2. Slowly turn crankshaft in direction of en- gine rotation until the timing needle cor- responds to the feed begin marking and/ or the respective degree marked on the pulley or on the counterweight (see Figure 0-6/1 and 00-6/17} or until the feed begin marking ct the flywheel is located in the center of the inspection hole of the clutch housing (see Figure 00-6/4 and 00-6/5). Note: All engine types of the model OM 636 ‘are now furnished with a timing needle ond with a TOC marking and markings ot 20°, 25° and 30° BIDC on the belt pulley of the crankshaft (see Figure 0-6/2). 3. Loosen the injection pump at the support- ing flange so that it can just be turned. 4, Then determine feed begin by turning the injection pump in the respective direction. 0-6/8 ‘On the OM 636 turning the injection pump towards the engine causes a retarded feed begin, turning away from the engine cau- ses the opposite. ‘On the OM 621 turning the injection pump towards the engine causes an advanced feed begin, turning away from the engine causes « retarded feed begin. The injection pump is set to feed begin if the fuel has just stopped dripping at the overflow tube. After approx. 15 0 20 se- conds one additional drop may follow {see Figure 00-6/13). Fix injection pump in this position by tightening 2 hex nuts and check adjustment again (see Sec- tion I Note: During the turning of the injection pump remove injection lines, if necessary. 5, If the adjustment is correct, tighten all hex nuts well for attachment of injection pump. 6, Unscrew the fuel tank (1} and the over- flow tube (4) (see Figure 00-6/10).7. Unscrew pipe connection nipple (4), install pressure valve (2) and tension spring (3) (see Figure 00-6/9). Screw in pipe connec- tion nipple again and tighten with a torque of 45 + 0.5 mkg (325 + 36 ft. Ib]. To guarantee perfect seat of sealing ring, loosen pipe connection again and tighten with 4.5 + 0.5 mkg for the second time, loosen for the third time and tighten again with 4.5 + 0.5 mkg. Attach clamping jaw lock between pipe connections; in doing $0, tighten attaching bolts with a torque of 0.9 mkg (6.5 ft. Ib} {too much torque on the low or high pressure elements may cause leaks or distortions of the injection pump casing). Connect injection line. Applying too high or too low a torque when tightening the connection nipple may cause irregulorities and trouble on the pump and on the engine. In the case of the OM 621 also observe the following: before screwing in the pipe connection (1), insert @ new seal ring (4) each time (part. No. 001 997 34.40 for in- jection pump PES 4M... R3, RS 3, R4 ‘and PES 4M... RS 14, or port No. 001 997 17 40 for injection pump PES 4M ... RT, R 1/2 ond R 1/24, respectively. Check rubber seal ring (2) for damage (see Figure 00-614}. Additionally, it should be mentioned that the pressure valve holder (5) with pressure valve, seal ring (4) and pipe connections (1) of the reinforced injection pumps PES 4M...R3,RS3,R 4 and RS 14 are not interchangeable with those of injection pumps PES 4 MR 1, R 1/2 and R 1/24 (see Figure 00-6/14), 3 2 Fig. 00-6/14 1 Pipe conection nile 2 Seal ring rubber) 5 Serna 4 Seal ring (brome ‘Prone valve eliar ih prema valve 3 3 4. When installing the pressure valve make sl that the parts are clean, because dirty valves can cause engine trouble. 8. Bleed the fuel system (see Job No. 00-10}. 9. Operate installed engine and check con- nections for leaks. Nol IV. Making Markings at Installed or Removed Engines OM 636 without Markings 1. Set piston of Ist cylinder to ignition dead center (see Job No. 00-3, item 3). 2, Remove glow plug of Ist cylinder, turn crankshaft approx. 50 deg opposite to direction of rotation, so that the crankshoft is approx. 50 deg BTDC. Note: On engines with injection timing device the crankshaft must be turned 13% revolu- tions in the direction of engine rotation The injection timing device must also be checked on its idling stop position (see Section Il, Note of Pos. 2). 3. Disconnect ground cable at negative pole of battery for reasons of safety. 4, Use valve lifter to press inlet valve down- wards and insert a feeler gauge of a given thickness (a) between valve stem ond rocker ‘arm (see Figure 00-6/15}. ange Dee. 62 ~ Workshop Manual OM TG a i | Fig. 00-6/15 a = Thickness of feeler gauge 0-6/9For the feed begin at 32° BIDC = a feeler gauge 12 mm thick 30° BIDC = a feeler gauge 10.50 mm thick @ feeler gauge 8.75 mm thick 26° BIDC A tolerance of 0.375 mm corresponds to Vp deg at the crankshaft. Note: The operations according to Paragraphs 4, 5, 6 and 7 should only be performed by conscientious and good speciali 5. Carefully turn crankshaft manually until the piston crown touches the valve disc (see Figure 00-6/15). Turn crankshaft af fixing screw (8), which serves to secure the pulley to the crankshaft, with box spanner 27 mm wide and ratchet or with «@ double box wrench with offset head or turn ot fan (see Figure 0-3/1) Do not crank engine with the starter. 4. IF the crankshaft is set to the correct feed begin attach the timing needle to the tim- ing housing cover and make a marking on the belt pulley. The marking and the tim- ing needle must correspond. With the help of the timing needle and the marking on the pulley the feed begin can be cor- rectly checked and adjusted any time after- wards. 7. Turn crankshaft approx. 30 deg opposite to engine rotation. Press inlet valve down- wards by using valve lifter to remove the feeler gauge inserted between the valve stem and the rocker (see Figure 006/15) 8. Connect ground cable to negative pole of battery 9. Check feed begin and adjust (see Section I! ‘nd Il) V. Checking and Adjusting Feed Begin with Stroke Advance Tester The feed begin can also be adjusted with the Stroke Advance Tester Part No. 000 589 68.21 for the OM 636 and with the tester Part No. 000 58985 21 for the OM 621 on removed engines. On installed engines the use of the stroke advance tester is not possible on all types due to the limited space. In this case determine the feed begin by measuring the stroke advance of the plunger. The Feed Begin for all Inje Pumps of the Engines Model OM 636 and OM 621 correspond to a Stroke Advance of the Pump Plunger of 1.7 + 0.1 mm, starting at Bottom Dead Center. 4) Checking Feed Begin 1, Remove the protecting cover of the in jection pump tappet housing 2, Rotate engine in operational direction until the push rod for the piston of the Ist pump cylinder is at bottom dead center. 3, Put stroke advance tester (1) to the pump in such a way thot the measuring pin (2) comes to rest on the push rod of the first pump cylinder (see Figure 00-6/16). The dial gouge must be pre-loaded approx. 0.5 mm at the same time. Then turn the scale of the dial gauge so that the needle points to zero. 00-6/10 4, Turn engine slowly in direction of rotation until the dial gauge indicates a movement of 17 + 0.1 mm. Note: In order to eliminate faults in measuring during the cranking of the engine, press stroke advance tester well against the support at the injection pump. 5. In this position of the injection pump the feed begin marking and/or the correspond- ing degree on the pulley (see, 4/1) oF on the flywheel must coincide with the timing needle (see Figure 00-6/6) or the hexagon screw must be situated be- tween the two lines marked with "FB" on the flywheel (see 0-6/7)Figure 00-6/16 1 Stoke Advance Tesla 00 6 482 » Mocsuring pina sate advonce Tester b) Adjusting the Feed Begin 1, Execute operations according to Point & Paragraph 1 to 3. 2. Set engine to feed begin. The feed begin marking or the respective degree value on the pulley andjor the flywheel must coincide with timing needle. B. OM 621 3. Loosen injection pump at supporting flange so that it can just be turned. 4. Press stroke advance tester well against ‘the support at the injection pump and turn the injection pump in such a woy that the dial gauge indicates a movement of 17 +01 mm. towards the engine causes a retarded feed begin, turning the other way causes ad- The injection pump is now also set to feed begin. Secure injection pump in this position. turing the turning of the injection pump disconnect injection lines if necessary. 5. Test adjustment of feed beginning (see Section o) and correct again if necessary (also see Job No. 07-5, Section Il, Point c, adjusting stroke advance and checking feed begin), |. Checking and adjusting of the feed begin according to the overflow method (spill method) with the engine installed or removed 1, Set the piston of the Ist cylinder to the ignition dead center (see Job No. 00-3, item 3} 2. Check this position on the counterweight at the front of the crankshaft. The odjust- ing pointer (2) must point approximately to the TDC mark on the counterweight (1) (see Figure 00-6/17}. Note: For checking and adjusting of the feed begin and the TDC, the OM 621 engines are provided with an adjusting pointer on the cylinder crankcase and a gradation on the counterweight of the crankshaft (see Figure 00-6/17). 3. Carry out operations as under A, Model OM 636, Section II, items 2-5. 4, Carry out operations as under A, Model OM 636, Section Il, items 1-9. 00-6/11Figure 00-6/16 1 Stoke Advance Tesla 00 6 482 » Mocsuring pina sate advonce Tester b) Adjusting the Feed Begin 1, Execute operations according to Point & Paragraph 1 to 3. 2. Set engine to feed begin. The feed begin marking or the respective degree value on the pulley andjor the flywheel must coincide with timing needle. B. OM 621 3. Loosen injection pump at supporting flange so that it can just be turned. 4. Press stroke advance tester well against ‘the support at the injection pump and turn the injection pump in such a woy that the dial gauge indicates a movement of 17 +01 mm. towards the engine causes a retarded feed begin, turning the other way causes ad- The injection pump is now also set to feed begin. Secure injection pump in this position. turing the turning of the injection pump disconnect injection lines if necessary. 5. Test adjustment of feed beginning (see Section o) and correct again if necessary (also see Job No. 07-5, Section Il, Point c, adjusting stroke advance and checking feed begin), |. Checking and adjusting of the feed begin according to the overflow method (spill method) with the engine installed or removed 1, Set the piston of the Ist cylinder to the ignition dead center (see Job No. 00-3, item 3} 2. Check this position on the counterweight at the front of the crankshaft. The odjust- ing pointer (2) must point approximately to the TDC mark on the counterweight (1) (see Figure 00-6/17}. Note: For checking and adjusting of the feed begin and the TDC, the OM 621 engines are provided with an adjusting pointer on the cylinder crankcase and a gradation on the counterweight of the crankshaft (see Figure 00-6/17). 3. Carry out operations as under A, Model OM 636, Section II, items 2-5. 4, Carry out operations as under A, Model OM 636, Section Il, items 1-9. 00-6/11Note: Because better ond safer adjusting valves are obtained bythe overflow method than by the capillary tube method, (which has been described on page 21 of the ‘Introduction to Models 190 D and 220 SE for Service and Maintance’), we ask you to use principally the overflow method in future. Figure 00-6/17 2 aleniog porter pile 3 fen ha atren 9 sero plvg for ol pressure 4 wore pum ‘el vaio Sten to Seren plog wth pivot in 3 Seeder tne ‘srgue ral 7 eyinder he 1 enaine sensor Il, Checking and adjusting of the feed begin with the stroke advance tester ) Checking of the feed begin 1, Remove the cover for the tappet chamber of the injection pump. 2. Turn the engine in direction of rotation until the tappet of the Ist pump cylinder is in BDC, 3, Fit and screw the odvance stroke tester (5} to the injection pump in such « way that the measuring pin (4) of the advance Figure 00-6/18 2 Clamping places with guise oroove ‘or clomping row oil seen 3 Somat ad stoke tener Hose pat Ne. onsaves hon na serene 3 Taig ing 00-6/12 stroke tester properly sits on the tappet sleeve (7) of the Ist pump cylinder, however, does not graze on the tappet spring (6) (see Figures 00-6/18 and 00-6/19). The dial gauge must then have @ pre-tension of approx. 0.5 mm. Turn the graduated ring on the dial- gauge until the pointer points to zero.Figure 00-6/19 1 contol arm with pin ond conrolsaeve 2 Stomping place wih gies groove "x por No, om0ss78821 4, Slowly turn engine in direction of rotation until the dial gauge shows 1.7+0.1 mm, Note: With the advance stroke tester mounted, not possible to go on tuming until TDC, because the feeler (4) of the advance stroke tester touches the control rod (3} (see Figure 00-6/19). 5. In this position of the injection pump, the respective degree value (26 deg) on the counterweight (1) must coincide with the adjusting pointer (2) (see Figure 00-6/17). IF necessory, correct adjustment (see para- graph b). b) Adjustment of feed begin: 1. Carry out operations acc. to section o) items 1 t0 3. 2, Set the engine to feed begin by slowly turning in direction of rotation, i.e., until the respective degree value (26 deg) on the counterweight (1) corresponds with the adjusting pointer (2) (see Figure 00-6/17}.. Note: With the advance stroke tester mounted it is not possible to go on turning until TDC, because the feeler (4) of the advance stroke tester touches then the control rod (8) (see Figure 00-6/19). 3. Loosen injection pump on mounting flange so that it can just be turned. 4, Then turn the injection pump so that dial gauge shows 1.7+0.) mm. In the case of the OM 621 turning of the injection pump towards the engine results in an advanced feed begin, turning from the engine results in a retarded feed begin. Now, the injection pump is also set to feed begin. Tighten the injection pump in this position and remove the advance stroke fester. Note: For turning the injection pump, discon- ect the injection lines from the pump, if necessary. 5. Check the adjustment of the feed begin, (see section a) and if necessary, correct again (also see Job No. 07-5, section Il, item ¢, adjusting advance stroke and checking feed begin} 00-6/13E. Checking Adjustment of Camshaft to Crankshaft ‘A. OM 636 Job Ni 00-7 The camshaft gear wheel and the crankshaft timing gear are furnished with markings for checking the adjustment of the camshaft in relation to the crankshaft (see Figure 00-7/1) However, these markings con only be seen if the timing housing cover has been removed. In order to allow a checking of the adjustment between camshaft and crankshaft even while the timing housing cover is installed, the drive gear wheels of the injection pump have been furnished with additional markings (see Figure 00-7/3). The driving geor of the injection pump drive on the camshaft is mounted together with the cam- shaft gear on the camshaft by a pin and secured by a hexagon screw. Therefore, the position of the driving gear on the camshaft corresponds exactly to the position of the camshaft gear wheel. im > an Figure 00-7/1 1, Set piston of Ist cylinder to approx. ignition dead center (see Job No. 00-3, Paragraph 3). 2. Then turn the crankshaft in such a way that the OT-marking (top dead center) on the pulley coincides exactly with the timing needle (see Figure 00-7/2) or the OT-marking on the flywheel is situated ‘exactly in the center of the inspection hole in the clutch housing (see Figure 00-6/4 ‘and 00-6/5) or on removed engines the timing needle points directly to the OT- marking on the flywheel (see Figure 00-6/6) Figure 00-7/2 1 ein needle for OT and FS {BC Sa Toes becinnng) 2 Storing De) 3 Ghai for the hexagon screw is located exactly between the two lines marked with [OT] (see Figure 0-6/7). 3a. Remove protecting lid, if timing housing cover is installed (see Figure 00-7/3). 00-7/1Figure 00-7/3 IF the camshaft gear wheel is mounted correctly, the marked tooth of the driving ger on the camshaft must be located BLOM 621 between the two marked teeth of the driving gear on the drive shaft of the injection pump (see Figure 00-7/3) 3b. If the timing housing cover hes been removed, the camshaft gear wheel is mounted correctly if the marked tooth of the crankshaft timing gear is located be- tween the two marked teeth of the camshaft gear wheel (see Figure 0-7/1). 4. If a correction becomes necessary remove the timing housing cover (see Job No. 01-15). Remove the crankshaft timing gear so that the crankshaft timing gear with crankshaft can be turned without the camshaft. Turn crankshaft until the marked tooth of the crankshaft timing gear is situated between the two marked teeth of the camshaft gear wheel. In this position press crankshaft timing gear back onto its seat. Remount timing ho Job No. 01-15}. The adjustment check of the camshaft with respect to the crankshaft of Model OM 621 with overhead camshaft, driven by a double roller chain, is made possible through one mark each on the first camshaft bearing and the spacer washer of the camshaft (see Figure 00-7/4). Figure 00-7/4 1. Use a socket, size 22 and a ratchet spanner to tum the crankshaft on the collar screw at its front side in direction of rotation of the engine until the adjusting pointer (2) points to the OT (TDC) mark of the 0-7/2 gradation on the counterweight (1) (see Figure 00-6/17}, Note: In the figure the pointer points to 26 deg BTDC (feed begin). Turn the crankshaft only in the direction of rotation of the engine to ensure that the left side of the chain is tensioned, 2. Now, the marks on the spacer washer of the camshoft and on the first camshaft bearing must coincide (see Figure 00-7/4). In this position, position 1 and 4 ore in TDC. Thereby the piston of the Ist cylinder is in compression stroke position. 3. If a correction is necessary, displace the double roller chain. (Displacement of the chain by one sprocket on the camshaft sprocket wheel corresponds to 18 deg. on the crankshaft, also refer fo the checking of timing (Job No. 00-8 and Job No. 05-36).Figure 00-7/3 IF the camshaft gear wheel is mounted correctly, the marked tooth of the driving ger on the camshaft must be located BLOM 621 between the two marked teeth of the driving gear on the drive shaft of the injection pump (see Figure 00-7/3) 3b. If the timing housing cover hes been removed, the camshaft gear wheel is mounted correctly if the marked tooth of the crankshaft timing gear is located be- tween the two marked teeth of the camshaft gear wheel (see Figure 0-7/1). 4. If a correction becomes necessary remove the timing housing cover (see Job No. 01-15). Remove the crankshaft timing gear so that the crankshaft timing gear with crankshaft can be turned without the camshaft. Turn crankshaft until the marked tooth of the crankshaft timing gear is situated between the two marked teeth of the camshaft gear wheel. In this position press crankshaft timing gear back onto its seat. Remount timing ho Job No. 01-15}. The adjustment check of the camshaft with respect to the crankshaft of Model OM 621 with overhead camshaft, driven by a double roller chain, is made possible through one mark each on the first camshaft bearing and the spacer washer of the camshaft (see Figure 00-7/4). Figure 00-7/4 1. Use a socket, size 22 and a ratchet spanner to tum the crankshaft on the collar screw at its front side in direction of rotation of the engine until the adjusting pointer (2) points to the OT (TDC) mark of the 0-7/2 gradation on the counterweight (1) (see Figure 00-6/17}, Note: In the figure the pointer points to 26 deg BTDC (feed begin). Turn the crankshaft only in the direction of rotation of the engine to ensure that the left side of the chain is tensioned, 2. Now, the marks on the spacer washer of the camshoft and on the first camshaft bearing must coincide (see Figure 00-7/4). In this position, position 1 and 4 ore in TDC. Thereby the piston of the Ist cylinder is in compression stroke position. 3. If a correction is necessary, displace the double roller chain. (Displacement of the chain by one sprocket on the camshaft sprocket wheel corresponds to 18 deg. on the crankshaft, also refer fo the checking of timing (Job No. 00-8 and Job No. 05-36).Testing Timing In general, there ore no changes in the valve timing of the engine Model OM 636 or only slight ‘ones due to the wear of the timing gears and cams, but this has no essential effect on the power output of the engine. It might happen, however, that by installing the wrong or inexactly machined camshaft the timing no longer corresponds to the specified values. Furthermore, a shifting of the timing is caused by can incorrect setting of the camshaft. In other words, the timing is shifted by the same amount and in the same direction as the camshaft is incorrectly set. In the case of the OM 621 the timing may vary after a longer period of operation owing to re- machining of the separating surfaces of the cylinder crankcase or of the cylinder head or owing to an elongation of the double roller chain. Generally, this slight variation will not seriously affect the power of the engine. If necessary, it can, however, be corrected by offsetting a key on the camshaft. Because the feed begin is also varied thereby, it is imperative to check and correct it in all these cases (see Job No. 00-6). Testing the timing with the specified valve clearance (operating valve clearance) is not suffi ciently accurate. Therefore, the timing of the inlet and exhaust valves is listed for a valve clearance of 0.4 mm, But this test valve clearance is not adjusted, only the test measurements are conducted at a valve lift of 0.4 mm, because this method is considerably more accurate. By measuring at a valve lift of 0.4 mm the some timing is obtained as by basing the test on the valve clearance of 0.4 mm. In general, itis sufficient to carry out the testing of the the Ist cylinder only. jing at the inlet and exhaust valve of The test measurements cannot be carried out on all installed en; 1e types due to lack of space. The Testing is performed as follows: 2. Remove all glow plugs and remove the cylinder head cover. 1. Attach suitable scale with a 360 deg graduation to the crankshaft and a timing 4 the piston of the Ist cylinder to needle to the timing housing cover (Figure * gel tne pisto evlinder to ignition 0-8/1). Note: With the OM 621 the gradated disc 4: Now turn the scale (1) in such a way that port No. 1805890723 (360 deg gradation) the needle (2) points to the 0 deg mark Can be mounted on the camshaft in place Secure scale in this position. (Figure 00-8/1.) of the crankshaft (see Figure No. 00-8/2) Note: Depending on the design of the pulley Do not fail to observe here that the values use a longer fixing screw and a correspond- read on the camshaft must be doubled! ing spacer, 0-8/1Figure 00-8/1 1 Seale 2 Tialng Neeste Figure 00-8/2 This figure shows the measurement token at an installed gasoline engine, Model 190 ‘radoted die, port No. 1805870722 2 Soinorimonsiacure youre) 3 fear pin 4 diet gruge holder part No, 198589012 5. In order to eliminate the given operating valve clearance insert a tolerance gauge between the valve stem end and the rocker in the case of the OM 636 and the rocker and the cap nut of the valve in the case of the OM 621 (see Figure 00-8/3) The tolerance gauge must be at least thick enough to safely ‘ate the available operating valve clearance. It does not make any difference if the valve is slightly lifted in the progress. 6. Screw the measuring pin (2) into the dial gauge and ottach the dial gauge by means of the dial gauge holder to the fixing bolt of the rocker brackets, so that the measuring pin has a tension of 2.0 mm and stands vertically on the spring retainer of the inlet valve of the Ist cylinder (Figure 00-8/3). Note: The measuring pin of the dial gauge must be exactly vertical to the surface of the spring retainer, otherwise conside- rable measuring mistakes will result. In the case of the OM 621 it to also properly bleed the chai perative tightener. 7. Now set the scale of the dial gauge to zero. Figure 0-8/3 1 Diol Govoe 2 Meouwring Pia 53 Tolerance GougeChange: items 1] to 13 are new 8. Turn the crankshaft in the direction of engine rotation, so that the dial gauge indicates 0.4 mm less, in other words, until the valve has been lifted 0.4 mm. Now read the value indicated at the gro- duation scale. valve i opening. ficates the beginning of valve (As regards timing, refer to Job No. 00-0.) If the graduated disk on the OM 621 is mounted on the camshaft, double the in- dicated value. 9. Continue to turn the crankshaft in the direction of engine rotation until the valve is still lifted 0.4 mm during the closing procedure, meaning the dial gauge in- dicates the same value as at the beginning of opening. During this procedure make sure that the adjusted tension of the dial ‘gauge of 2.0 mm is maintained. The following offset keys are ovailable: Read the value indicated at the gradua- tion scale. The indicated value stands for the end of closing of the inlet valve. direc- Note: Never rotate engine in opposi tion during test procedures, because the be considerable measuring takes. To check the reading turn the engine until the needle (2) points to the O-deg mark on the scale (1) (see Figure 00-8/1).. At the same time the. dial gauge must go back to zero. 10. Check the timing of the exhaust valve in the same way. 11. If an adjustment of the timing is necessary, install an offset key or a new camshaft. Offsetting the key toward the right (seen in driving direction) results in advanced feed begin. Offsetting the key toward the left results in retarded feed begin. A 0.20 mm offset of the key corresponds to approx. 1° 30’ crankshaft 3° 20" = 0.9 mm, Part No. 621991 0267 for an adjustment of approx. 62° crankshaft 4° = 1.1 mm, Part No. 621 991 01 67 for an adjustment of approx. 8° 1.3 mm, Part No. 621 991 00 67 for an adjustment of approx. 5° crankshaft 10° crankshaft Offsetting the camshaft by one tooth will shift the feed begin on the OM 636 approx. 14° 30° and on the OM 621 approx. 18° crankshaft. Exampl If the inlet valve on model OM 621 — type 621.912, 621.913 and 621.914 opens at 6 crankshaft only, there is a difference of 6Y/ crankshaft degrees on the camshaft as compared to the crankshoft. Shifting of 6 crankshaft degrees can be done by installing a key offset by 3° 20’ Oifsetting the choin by one footh on camshaft gear toward the left when seen from front, results in shifting the comshaft or resetting the feed begin by approx. 111 crankshaft degrees, respective- ly, when the key which is offset by 3° 20 is inserted in reverse. 12, Checking valve spacing: Following testing and adjustment of timing, check space between inlet and exhaust valve disks and pistons on alll cylinders. inlet valve and piston ot 5° affer TDC shovld amount to mm | nf os exhaust valve and piston at 5° before TDC should amount to am | 1s | 28 T= Change Dee. 62 - Workshop Manual OM Diesel EnginesIF the space is smaller, there is the risk that the valve will knock against the piston crown. When making measurements, the dicl gauge and graduated disk are fitted in the same way as for measuring the timing. Then turn piston of cylinder to be measured — for example on model OM 621 — for determining spacing between inlet valve and piston on 5° after TDC (overlap dead center) and set dial gauge under preload from 3.00 mm to 0, The inlet valve is now pressed downwards so that it rests on piston. The dial gauge should now go back ot least 1.5 mm, refer fo table in our example. Note: Overlapping dead center = TDC prior to suction stroke. If the space between the valves ‘and the piston is smaller than stated in the table, lower valve seat correspondingly. (See Job No. 01-8.) In doing so, check first whether the small space is caused by oil carbon deposit on piston crown, or on valve disk, respectively. 13. Check feed begin and adjust Setting of feed begin, see Job No. 00-4, Section Il. A chain elongation of 5 mm corresponds to @ retarded timing of feed begin of approx. 2° on crankshaft. 0-8/4Measuring Suction and Discharge ‘Job No. Action of the Fuel Feed Pump 0-9 and Checking the By-Pass Valve Change: Fuel noise and muffler added The fuel feed pump has the task to deliver the fuel with a certain pressure but without bubbles to the suction space of the injection pump. Insufficient output of a pump causes engine trouble. Especially an engine operated in the full load range and at high speeds demands a certain charg- ing pressure to maintain @ satisfactory fuel supply to the pump elements. This charging pressure is kept at @ constant rate by the by-pass valve which is installed in the main fuel filter with the OM 636 and at the end of the suction space of the injection pump with the OM 621, opening at a pressure of 1 fo 1.5 aim. The discharge pressure can be checked in a simple way without any means as follows, provided that the by-pass valve is adjusted correctly: Disconnect the return line at the return line connector of the tank and put the end of the hose in © suitable container. Start engine. If fuel flows out while the engine is in operation, then the dis- charge pressure is higher than the opening pressure of the by-poss valve of 1 to 1.5 atm. The check- ing of the discharge pressure and/or opening pressure is more difficult at by-pass valves which cre furnished with a groove and/or hole in the valve disk fo eliminate a ticking in the fuel lines from and to the tank (see Page 09-3/4). In this case, the fuel jet leaving the end of the hose must be stronger. However, such a check is not sufficient in all cases. A more exact testing is possible by employ- ing the Feed Pump Tester 000 589 49 21 (see Figure 00-9/1). With the help of this instrument the testing of the peak pressure during the discharge stroke, the vacuum during the suction stroke and also the exact opening pressure of the by-pass valve has been made possible. Furthermore, @ glass tube installed in the instrument allows the observation of the fuel during the above tests, so that it can be seen whether the fuel is delivered without air. Testing Discharge Rate wil Testor Part No. 000 589 49.21 the Feed Pump replaced if necessary (see Job No. 09-3, Section c, Checking by-pass valve}. 1. Disconnect the pressure line between the 4. Check the peck pressure ofthe feed oum; fuel feed pump and the main fuel filter we peak pressure ofthe feed pump, i The highest discharge pressure of the feed and connect the instrument (see Figure pump will be indicoted by squeezing the 0-97), hose between the instrument and the fuel main filler. The pressure should at least be 2.0 atm. for a feed pump in satisfactory working order. 2. Bleed instrument and the fuel main filter at the bleeder screw of the fuel main filter ‘and operate engine (also see Job No. 00-10, items 1 and 2). 5. Check the vacuum during suction stroke. 3. The opening pressure of the by-pass valve indicated by the instrument should be 1 to 1.5 atm. If the indicated pressure is higher than 15 atm. or lower than 1 aim, then the by-pass valve has to be checked and Trange Dee. &2 - Workshop Manval OM Diesel Engin Connect the connectors of the instrument to the suction end of the feed pump. The suction vacuum should at least be 0.5 atm. Repair or exchange faulty feed pumps (also see Job No. 07-14, Checking and Repsiring Fuel Feed Pump}. 00-9/11 Connection tthe diac 3 Clon tbe 6. Watch the glass tube of the instrument during the testing of suction and discharge ection, whether there is cir contained in Fuel Noises (Ticking in the Lines) the fuel. In order fo determine the point where infiltrated air is sucked into the sys- tem, the instrument is first connected to the suction end of the feed pump and then, to the discharge end. If air bubbles can already be observed while the instrument is connected to the suction end, the leak is between the fuel tank and the fuel feed pump. 7. In addition to the above tests, the instru- ment can also be exploited to check the throughput of the filter. To make this test, connect the instrument between the fuel main filter and the injection pump. The pressure obtained here should only be slightly less than the indicated pressure before the filter. Very fouled filter cartridges cause a reduc- tion of pressure and possibly engine trouble. To dampen the fuel noises in the lines a muffler (Part No. 189 070 05 68 or Part, No. 198 070 00 68) can be installed into the fuel return line between injection pump or by-pass valve and fuel main filter or crosspiece, respectively. 0-9/2 Moffler If in spite of an installed muffler there are still fuel noises in the lines, the diaphragm of the muffler should be checked. A torn and damag- ed diaphragm should be replaced (Fig. 0-9/2). ‘When screwing together the upper and lower portion of the muffler, press diaphragm toward the top (Part No. 189.070 00 52).Bleeding Fuel System In order to obtain a satisfactory performance of the engine it is necessary that the injection pump is charged with fuel contai 1g no bubbles. Air in the fuel system can cause heavy knocking and «@ reduction of engine output and in certain cases starting trouble. In general, the bleedi of the fuel system is only necessary if the connections and lines are loosen- ed. However, bleeding can also become necessary during the operation, if the feed pump sucks infiltrated air. @) Bleeding Fuel Main Filter and Injection Pump. 1. Unscrew bleeder screw (1) at fuel main filter 1 to 2 turns (see Figure 00-10/1). Note: OM 621: the bleeder screws arranged hitherto laterally have been omitted and are now replaced by one bleeder screw (5) ot the top of the injection pump, ie. ot the rear and of the suction space (see Figure 00-103). Figure 00-10/1 OM 636 2 Engine model pote 2. Turn the control knob of the hand feed pump (1) in direction (2) and pump until fuel without bubbles flows out of bleeder screw (see Figure 00-10/2) Then close again the bleeder screw (1) (see Figure 00-10/1), 3. On OM 636 unscrew the two bleeder screws (4 and 5) ot the pump for several turns Operate hand pump again until fuel without bubbles flows out at the bleeder screws. Secure the bleeder screws. Tighten the control knob of the hand feed pump by turning, it clockwise (see Figure 00-10/2). Figure 0010/2 OM 636 fee 9 Secor 5 Bleeder Screw 4 Bleeder Screw The injection pumps of initial production are still equipped with 2 bleeder screws. On no account forget to secure well the control knob of the hand feed pump. By tightening the control knob the pump plunger is pressed onto a gasket ring thus sealing the hand pump. If the control knob is loose, the hand feed pump leaks during ‘operation. b) Bleeding injection lines With the OM 621 bleeding of the injection lines is not necessary, since these are very short (approx. 320 mm long as compared to approx. 750 mm with the OM 636). 00-10/1The bleeding of the injection lines is only necessary ifthe lines had been disconnected ‘and had therefore been completely drained. 1. Remove side cover ofthe injection pump. 2, Set the respective pump element to full stroke by turning the crankshaft, so that the pump plunger and push rod are situated at bottom dead center. Then pump with a suitable tool between the lock nut and the adjusting screw of the roller tappet until the 00-10/2 ¢ a Figure 00-10/4 OM 636 corresponding nozzle discharges (see Figure 0-10/4). However, do avoid unnecessarily prolonged injecting. Bleed all injection lines. . Reinstall the side cover of the injection pump. Operate engine and check all connections and bleeder screws for leaks.Adjusting Idling Speed Tob N 00-11 The idling speed of an engine is the lowest speed at which the unloaded engine continues to run without stolling; during this operation the engine is only carrying the load caused by its internal friction and the aggregates such as generator, injection pump, fan etc. which are always coupled with the engine. Therefore, the engine needs a small injection quantity. This is automatically adjusted by the gover- nor of the injection pump, as soon as the throttle butterfly is in the idling position. The engine must be at operating temperature to allow the correct adjustment of the idling speed (cooling water temperature at least 60° C]. The engine can be warmed up during a previous short trial run if necessary. The specified idling speed should only be adjusted at the throttle duct and not at the injection pump governor. The adjustment of the helper spring in the governor serves only to eliminate "sawing and galopping” during idling {see Job No. 07-8, Section Ill). The idling speed should be set to 550 to 600 rpm for OM 636 and 700 to 800 rpm for the OM 621. IF no revolution counter or no hand revolution indicator is available, then the charging control light can be employed as « serviceable indicator. The idling speed is adjusted in such a way that the charging control light is just dimmed. The idling speed of diesel engines should rather be adjusted too high than too low in order to obtain a smooth and balanced operation of the engine. Furthermore, this will reduce the strain on the flexible suspension of the engine and exhaust essembly used for passenger car engines @) Adjusting the idling speed at the throttle Regarding the OM 621: besides the operations duct ‘according to items 1 and 2, the connection rod (26) of the mechanical “additional control should also be checked for correct length 1. On vehicles with bowden cable idling con- and/or adjusted. trol, turn the knob at the instrument panel fully clockwise. The throttle lever (4) should not touch the setting ring of the bowden cable (see Fig. 00-11/1], loosen the setting ring if necessary 2. Then adjust the idling speed by tightening or loosening the idling stop screw (2) (Idling Speed see Job No. 00-0} Note: If the speed cannot be lowered suffi- ciently, then check whether the vacuum line, the diaphragm housing or the diaphragm. Figure 00-11/1 is leaking. If there is a leak in the vacuum rullond oo system, an idling adjustment is not possible, 2 laling sop tern 5 Vocutm connector because the vacuum will be too weak to pull the control rod far enough in the direc- Seer ee ctw erat tion STOP (also see Job No. 07-8, Section | & Glow slea, cond Ill) 3 Groend cle ooTo do this unhook the connection rod (26) from the angular lever (24) on the cylinder head cover to the lever (28) of the mechani- cal additional control (Stupser) on the injec- tion pump governor and press downwards to the idling stop (see Figure 00-1/12). In this position, i.e., throttle in idling posi- tion and lever (28) on the injection pump governor, a distance of approx. 1 mm must exist between the ball socket of the con- nection rod (26) and ball head on the angular lever (24), that means for hooking of the connection rod (26) into the ball head of the angular lever (24), the con- nection rod (26) must have a lift of approx. 1 mm. If, for hooking in, the connection rod must be lifted by more than 1 mm, then elongate the connection rod by unscrewing 3 odlusting lover 4 Saeser screw 4 en hd & ferow plug 5 ination tne 5 Fnible ss fom by-pass valve of Iecton pune tothe cose ting 9 crore ang (fon nd rew nection for revaltion cote 14 Bleeder ine fom tro ros fing 1S how hd crew for fir evntng 00-11/2 the ball socket. If the distance is smaller than 1 mm, the connection rod must be made shorter. b) Adjusting the bowden cable of the control OM 636 and OM 621 Adjust the bowden cable only after the idling speed hos'been adjusted at the idling stop screw (2) (see Fig. 00-11/1). 1. Turn the knob at the instrument panel fully clockwise. 2. Clamp the set ring on the wire cable in such a way that there is a distonce of 0.1 to 0.2 mm between set ring and throttle lever or angular lever resp., so that, the idling stop screw surely touches ifs stop on the throttle duct. With this adjustment, the engine speed increases when turning the turn button towards left approx. as from the 4th notch. Note: With the OM 621, do not fail to check the wire cable (18) for free movement in the slot of the stop angle at the angular lever (24) (see Figure 00-11/2). We 1? Boxible hove from tckage 1f wir st for ing tae 2B connection tod 200m long) B thrash th lever 24 orauor lover 25 lastage line 28 connection tod to lever for mechonigal additions control 2 sccuum in from ction sump governor fo thro Soc 2 over for masini! cedsional Conta! B sopporing bel 5 Sepponing corerAdjusting No-Load Maximum Speed Change: Note and Table on Poge 00-1212 added In the highest speed range of an engine there are two speeds, the full-load mox. speed and the no-load mox. speed. Higher maximum speeds as those stated (see Job No. 00-0 and 0-2) ore net permissible for me- chanical reasons and because of carrying along of oil and dirt from the air filter. ©) Full-Load Max. Speed: The full-load max. speed, also called rated speed, is the speed which the engine should reach ‘at max. power output. The throttle butterfly is fully opened against the full-load stop. At low speed there is at first only a small vacuum in the vacuum chamber. The vacuum necessary for governing and the required force to pull back the control rod in the direction STOP will only be obtained if the throttle butterfly is fully opened and during full-load max. speed. At the some time, the compensating spring will be completely relieved but is still lightly resting on the full- load stop (see Fig. 07-4/13). As soon as the engine has reached its full-load max. speed the pulling back of the control rod in the direction STOP begins and with it the limitation of the no-load max. speed (beginning of governing) b) No-Load Max. Speed: The no-load max. speed is the speed which the engine can reach in extreme cases but should never surpass for longer periods without endangering the engine or one of the units driven by the engine. IF for instance the throttle is opened fully while stationary or during a downhill drive, the speed surpasses the full-load mox. speed. The vacuum increases so that the diaphragm is lifted away from the full-load stop and is pulled further in the direction STOP against the Stupser. Even though the governor goes into action (the injected quantity becomes smaller) while the dia- phragm is leaving the full-load stop, the engine speed still increases due to the small load. The speed continues to increase until the diophragm is pulled so far back that the pump plunger passes the partial load and idling position and reaches the range of no delivery. The Stupser is compressed during this process. The diaphragm and control rod thus travel through the idling position into the no-delivery range of the injection pump as is exactly the case during the stopp- ing of the engine (Figure 074/14 and Figure 07~4/15}. Therefore, a further speed increase is im- possible in this position of the governor (end of governing). Note: The above description shows that the position of the Stupser is of essential importance for the no-load mox. speed. A required adjustment of the Stupser fo smoothen idling operation should therefore be conducted very carefully (see Job No, 07-8, Section Ill), ¢) Adjusting No-Load Max. Speed: Warm up engine, then accelerate by opening throttle butterfly, as far as possible and measure no-load max. speed with revolution counter. If the no-load max. speed is higher than specified for the respective type in the technical data (see page 0-1/11 and next page, as well as 0-2/1) The full-load stop screw must be screwed in so far thot the specified speed will be obtained (see Figure 00-11/1) 00-12/1 T= Change Dee. 62 — Workshop Manual OM Diesel EnginesIf the no-load max. speed is not reached, then open the throttle butterfly and/or increase the speed by unscrewing the full-load stop serew (1) (Figure 00-11/1) Since the vacuum of the individual engines are never exactly the same, it may happen that the full-load stop screw and/or the throttle butterfly position during full throttle have to be adjusted (see Job No. 07-23) IF the throttle butterfly is already opened as far as possible, the governing spring of the injection pump must be further pre-loaded by means of spacer rings (for OM 636 see Fig. 00-12/1, Pos. 20, for OM 621 see Fig. 00-12/2, Pos. 14). Then measure no-load max. speed and if it corresponds to the valves listed in the technical data, attach lead seal to governor housing of injection pump {see Figure 07-5/1), The subsequent installation of a spacer ring must therefore be done by one of ‘our agencies which are in possession of lead pliers of the Bosch company, or it must be done in cooperation with the nearest Bosch Service Agency. The installation of one spacer ring 1 mm thick results in an average increase in engine speed of approx. 120 to 150 rpm on the OM 636, depend- ing on the properties of the individual governing spring, Spacer ring 1.0 mm thick, Part No. 180990 18 40 Spacer ring 0.5 mm thick, Part No. 180990 17 40 Spacer ring 0.2 mm thick, Part No. 180990 16 40 Note: Instead of measuring the no-load mox. ee es Perm speed (changing-down end), the full- ‘Tachometer iselication load max. speed (begin of changing | | down at full load) or the permissible Model 2nd Gear | 3rd Gear | eed of vehic i, | mox. speed of vehicles in 2nd and 3d | 70> 7a 0 ope, | gear con be checked and corrected in 17008, 17080, 5 ” accordance with tachometer indication. | 180, 180 Db, 180De For permissible max. speeds refer to 90D —T | table at right. Higher speeds ore not 190 Db 36 89 permissible for mechanical reasons and because of the possibility of carrying nabs one ine along oil and dirt from the air filter. with engine e a 2B a OD with engine oman 2 55 Fig. 00-12/1 Particl Load or Idling Position OM 636 1 Venting sainer for olmoaphric chomber 2 Flopsype eile for tubricatingpoveror linkage 3 Dieptroge Goel ting 6 Aajing sere with odor spring (St 7 Fixing nat for adivtng seem 8 Additonal sping 9 Stop pin (tse) 1 Adjtingserew wth ulHood op 12Sping 13 Sop 7 1 Recdioting lever 16 Cone! ro 17 Cap in diaphragm blk housing cover 19 Prenure pn ofthe adoption spring A sm 129 Spocer ving 00-12/2one ot 6a 5b T= Change Dee 62 - Workshop Manual OM Diesel Engines Fig. 00-12/2 Idling Position of OM 621 1 Ai iter 2 Guide od 4 Adoption sering 4 Prenre pin of adoption spring 7 String quantity sop 9 Dovble lever 10 Diephrogm 1 Robber Boer 12 Voevum conection on he vacuum chamber M4. Spacer ring 1s Engng com, flood postion ling potion 17 Stop pin (Supe 18 Addiionl ering 19. Shaper howtng andlor pring cape, siding 2 Sop infor fload Hop 2 Fang mut 1. Adjotog sere wit ullond sopAdjusting Cable Control between Glow Starter Switch and Injection Pump ‘A. OM 636 1. Turn the handle (2) of the glow starter switch (1) fully counterclockwise (stop position) and at the same time have a second person check the position of the control lever (6) at the injection pump. In this position the control lever (5) at the injection pump must be fully drawn back to the stop position by the eye (4) of the cable control (see Figure 00-13/1). The plungers of the injection pump are then in the no-delivery position, the engine no longer receives fuel and stops. The cable control can be adjusted by shifting the wire spircl (sleeve) in the fixing clip or by moving the wire cable in the lever of the glow starter switch. The control lever (5) must be securely fixed on the shaft of the injection pump (see Figure 00-13/1). + 2 12 3 _ 4 ——5 5 © Figure 00-13/1 Figure 00-13/2 Stop Position Storting Position 1 Gtow trer swith } Glow strter si 2 Rika lowest vn doy potion 2 Mend te ters toring postion 4 Eye of coble antral 4 bye of anble conte § Cont ever pled boc completely 5 Coot over pshed forvord completely foo se Tig, 15082 ond ob R162 2. Disconnect ground cable at negative pole of battery 3, Turn the handle (2) of the glow starter switch (1) ully clockwise starting position) and at the same time have a second person check the position of the control lever (5) at the injection pump. In this position the bolt of the control lever (5) must touch at the other side of the eye (4) (opposite to the stop position) and the control lever (5) must be pressed forward completely (see Figure 00-13/2). Thus the control rod has been shifted in the direction “full” beyond the full load stop to starting quantity 4, Release the handle (2) of the glow starter switch, the handle goes to the driving position, posi- tion 0. In the driving position 0 as well as in the pre-heating position 1 the bolt of the control lever should not touch the eye on either side. 5. Connect the ground cable with the negative pole of the battery. 6. Start engine, operate engine for a short period, turn knob of idling control (if installed) fully clockwise and stop engine again. If there are difficulties in adjusting, that is if the starting and stop position cannot be adjusted satisfactorily, a small part of the starting quantity can be abandoned in favor of a satisfactory stop position 0013/1Note: For built-in engines of fork lifts the starting quantity can be abandoned completely, if a short and dense smoke jet appears during starting. In such cases remove the cable control and attach a simple linkage to the control lever of the injection pump, which allows the stopping of the engine. B. OM 621 With the OM 621, i.e., vehicle model 190 D and 190 Db (left hand steering only} the glow starter ond stop switch features a push pull switch, contrary fo the rotary type switch installed in the OM 636 (see Figure 00-13/3). Further the control lever of the injection pump goes downwards contrary to the position of the control lever of the OM 636. 1. Disconnect the ground cable from the negative pole of the battery. Hetion Sarat me Einspritz- Glihanlad- und 2. Completely push in push pull switch knob Pumpe ‘Stopachatter (stop position) whilst second man checks 1505 the position of the control lever on the s injection pump at the same time. In this position the control lever must be com- a ha fo I pletely pushed forward (see Figure 00-13/3, \ S = stop position). wie i F 3. Pull the knob of the push pull switch com- te eo fn pletely outwards to the stop overcoming the slight resistence (starting position) whilst @ second man checks at the same time the position of the control lever on the injection pump. In this position the pin of the control lever must contact the other side of the lug {contrary to the stop position} the control lever being completely drawa rearwards wise (see Figure 00-13/3, A = starting position). A 4, Release the knob of the push pull switch, through its spring force the switch auto- J matically moves to driving position. If in = driving or pre-glowing position, the pin of the control lever must not contact either side of the lug (see Figure 00-13, F = driv. oe ing position, V = pre-glowing position). #5 devine pesion = gre-alowing positon A toring postion Figure 00-13/3 5. Connect the ground cable to the negative pole of the battery. 6. Start and operate the engine for a short time, turn the rotary hondle for the idling adjustment (if any) completely to the right and stop engine again. Should adjusting difficulties arise, i.e., if starting and stopping position cannot be properly adjusted, adjust in favour of a faultless stop position at the cost of a small part of the starting quantity. 00-13/2,Note: For built-in engines of fork lifts the starting quantity can be abandoned completely, if a short and dense smoke jet appears during starting. In such cases remove the cable control and attach a simple linkage to the control lever of the injection pump, which allows the stopping of the engine. B. OM 621 With the OM 621, i.e., vehicle model 190 D and 190 Db (left hand steering only} the glow starter ond stop switch features a push pull switch, contrary fo the rotary type switch installed in the OM 636 (see Figure 00-13/3). Further the control lever of the injection pump goes downwards contrary to the position of the control lever of the OM 636. 1. Disconnect the ground cable from the negative pole of the battery. Hetion Sarat me Einspritz- Glihanlad- und 2. Completely push in push pull switch knob Pumpe ‘Stopachatter (stop position) whilst second man checks 1505 the position of the control lever on the s injection pump at the same time. In this position the control lever must be com- a ha fo I pletely pushed forward (see Figure 00-13/3, \ S = stop position). wie i F 3. Pull the knob of the push pull switch com- te eo fn pletely outwards to the stop overcoming the slight resistence (starting position) whilst @ second man checks at the same time the position of the control lever on the injection pump. In this position the pin of the control lever must contact the other side of the lug {contrary to the stop position} the control lever being completely drawa rearwards wise (see Figure 00-13/3, A = starting position). A 4, Release the knob of the push pull switch, through its spring force the switch auto- J matically moves to driving position. If in = driving or pre-glowing position, the pin of the control lever must not contact either side of the lug (see Figure 00-13, F = driv. oe ing position, V = pre-glowing position). #5 devine pesion = gre-alowing positon A toring postion Figure 00-13/3 5. Connect the ground cable to the negative pole of the battery. 6. Start and operate the engine for a short time, turn the rotary hondle for the idling adjustment (if any) completely to the right and stop engine again. Should adjusting difficulties arise, i.e., if starting and stopping position cannot be properly adjusted, adjust in favour of a faultless stop position at the cost of a small part of the starting quantity. 00-13/2,Figure 00-13/4 Figure 00-13/5 Arrangement of the wire cable mounting on the OM 421, i.e, vehicle Model 190D and 190Db ond stopping cable) 00-13/3,Disassembly and Assembly of Engine (Individual Removal of Assemblies and Parts) A. OM 636 B. OM 621 €. General Apart from a general overhaul only those assemblies and engine ports are normally removed which have to be repaired or tested. The operations have therefore been subdivided and arranged in such a way that all operations for removal and installation of the assembly or the part in question are given in the respective section. ‘A. OM 636 If an engine has to be completely stripped, the operations of the sections 1 through 20 have to be carried through. 1, Removal and installation of air filter (see Job No. 09-7). 2, Removal and installation of intake line with throttle duct and exhaust manifold (see Job No. 14-1 and 145}. 3, Removal and installation of starter motor (see Job No. 15-1) 4, Removal and installation of generator (see Job No. 15-11). 5. Removal and installation of injection lines, vacuum line and fuel main filter (see Job No. 07-15 ond 09-1), 6, Removal and installation of cylinder head (see Job No. 01-3} Disassembly of cylinder head: 4) Removal and installation of glow plugs (see Job No. 15-31). b) Removal and installation of nozzle holders with nozzles (see Job No. 07-17). J Removal and installation of prechambers (see Job No. 01-1). 4) Removal and installation of valves (see Job No. 05-11). ) Removal and installation of water pump (see Job No. 20-5). 4} Removal and installation of cooling water outlet pipe. 7. Removal and installation of oil filter (see Job No. 18-7). 8. Removal and installation of injection pump and fuel feed pump (see Job No. 07-11) 9. Removal and installation of fan bracket with pulley and support for fan bracket, if installed (see Job No. 20-15). 10, Removal and installation of operation hour counter, if installed (see Job No. 01-11). 11. Removal and installation of revolution counter drive, if installed (see Job No. 01-12). 12, Removal and installation of injection timing device, if installed (see Job No. 07-25}. 13. Removal and installation of timing gear housing cover (see Job No. 01-15}. 14, Removal ond installation of timing gears (see Job No, 05-31). 15. Removal and installation of oil pressure relief valve (see Job No. 18-3}. 16. Removal and installation of oil pan (see Job No. 01-21). 17. Removal and installation of oil pump (see Job No. 18-11) 00-20/118. Removal and installation of crankshaft and flywheel (see Job No. 03-5). Disassembly of crankshaft: ¢] Removal and installation of intermediate piece and crankshaft gear (see Job No. 03-5, section A, item 8). ') Removal and installation of flywheel (see Job No. 03-16). ¢) Removal and installation of grooved bearing and cap (see Job No. 03-17}. 19. Removal and installation of pistons with connecting rods (see Job No. 03-11} 20. Removal and installation of camshaft, camshaft bearings and valve tappets (sve Job No. 05-35). B. OM 621 |n an ingine hos to be completely stripped, the operations of the sections 1 through 20 have to be carried through. 1, Removal and installation of air filter (see Job No. 09-7). 2. Removal and installation of intake line with throttle duct and exhaust manifold (see Job No. 14-1 and 14-5) 1. Removal and installation of starter motor (see Job No. 15-1). . Removal and installation of generator (see Job No. 15-11). 9. Removal and installation of water pump with fan (see Job No. 20-5). Removal and installation of injection lines, vacuum line and fue! main filter (see Job No. 07-15 and 09-1). 7, Removal and installation of cylinder head (see Job No. 01-3) Disassembly of cylinder head: 2) Removal and installation of slide vail in cylinder head (see Job No. 05-29). b) Removal and installation of glow plugs (see Job No. 15-31). ¢) Removal and installation of nozzle holders with nozzles (see Job No. 07-17). 4) Removal and installation of prechambers (see Job No. 01-1). ) Removal and installation of camshaft with bearings (see Job No. 05-36). 4) Removal and installation of valves (see Job No. 05-11) g) Removal and installation of idler sprocket and idler sprocket bearing (see Job No. 05-23). h) Removal and installation of guide sprocket (see Job No. 05-25). 8. Removal and installation of oil filter (see Job No. 18-7) 9. Removal and installation of injection pump and fuel feed pump (see Job No. 07-11). 10. Removal and installation of oil pump drive (see Job No. 18-16). 11. Removal and installation of injection timing device (see Job No. 07-25) 12, Removal and installation of injection pump drive (intermediate geor shaft) (see Job No. 05-28). 13. Removal and installation of oil pressure relief valve (see Job No. 18-3). 14, Removal and installation of oil pan (see Job No. 01-21). 15. Removal and installation of oil pump (see Job No. 18-11). 16. Removal and installation of crankshaft with flywheel (see Job No. 03-5). Disossembly of crankshaft: 9) Removal and installation of counterweight, seal ring, spacer ring, oil thrower ring, erank- shaft gear spacer washer (see Job No. 03-5, section B, item 7} b) Removal and installation of flywheel (see Job No. 03-16). ¢] Removal and installation of annular grooved bearing and cap (see Job No. 03-17). 00-20/218. Removal and installation of crankshaft and flywheel (see Job No. 03-5). Disassembly of crankshaft: ¢] Removal and installation of intermediate piece and crankshaft gear (see Job No. 03-5, section A, item 8). ') Removal and installation of flywheel (see Job No. 03-16). ¢) Removal and installation of grooved bearing and cap (see Job No. 03-17}. 19. Removal and installation of pistons with connecting rods (see Job No. 03-11} 20. Removal and installation of camshaft, camshaft bearings and valve tappets (sve Job No. 05-35). B. OM 621 |n an ingine hos to be completely stripped, the operations of the sections 1 through 20 have to be carried through. 1, Removal and installation of air filter (see Job No. 09-7). 2. Removal and installation of intake line with throttle duct and exhaust manifold (see Job No. 14-1 and 14-5) 1. Removal and installation of starter motor (see Job No. 15-1). . Removal and installation of generator (see Job No. 15-11). 9. Removal and installation of water pump with fan (see Job No. 20-5). Removal and installation of injection lines, vacuum line and fue! main filter (see Job No. 07-15 and 09-1). 7, Removal and installation of cylinder head (see Job No. 01-3) Disassembly of cylinder head: 2) Removal and installation of slide vail in cylinder head (see Job No. 05-29). b) Removal and installation of glow plugs (see Job No. 15-31). ¢) Removal and installation of nozzle holders with nozzles (see Job No. 07-17). 4) Removal and installation of prechambers (see Job No. 01-1). ) Removal and installation of camshaft with bearings (see Job No. 05-36). 4) Removal and installation of valves (see Job No. 05-11) g) Removal and installation of idler sprocket and idler sprocket bearing (see Job No. 05-23). h) Removal and installation of guide sprocket (see Job No. 05-25). 8. Removal and installation of oil filter (see Job No. 18-7) 9. Removal and installation of injection pump and fuel feed pump (see Job No. 07-11). 10. Removal and installation of oil pump drive (see Job No. 18-16). 11. Removal and installation of injection timing device (see Job No. 07-25) 12, Removal and installation of injection pump drive (intermediate geor shaft) (see Job No. 05-28). 13. Removal and installation of oil pressure relief valve (see Job No. 18-3). 14, Removal and installation of oil pan (see Job No. 01-21). 15. Removal and installation of oil pump (see Job No. 18-11). 16. Removal and installation of crankshaft with flywheel (see Job No. 03-5). Disossembly of crankshaft: 9) Removal and installation of counterweight, seal ring, spacer ring, oil thrower ring, erank- shaft gear spacer washer (see Job No. 03-5, section B, item 7} b) Removal and installation of flywheel (see Job No. 03-16). ¢] Removal and installation of annular grooved bearing and cap (see Job No. 03-17). 00-20/217. Removal and installation of pistons and connecting rods (see Job No. 03-11) 18. Disassembly and assembly of cylinder crankcase (see Job No. 01-25). 19. Removal and instollation of front seal ring for crankshaft, engine not removed (see Job No. 03-3), 20. Removal and installation of double roller chain, with assembled engine (see Job No. 05-27}, C. General The engine should only be removed for a general overhaul if a bearing has been damaged or if it has been determined beyond doubt that an excessive oil consumption or decrease of output is due to faulty pistons and cylinders etc. (see Job No. 0-10). In addition to special knowledge and experience, special machine tools, measuring instruments, gauges and special devices are needed for the testing and repairing of engines, as it is described in the following Job Numbers. In the interest of the customers we therefore recommend utilizing the possibility os far as possible of exchanging complete engines (replacement engines) or individual components, such as cylinder crankcases, crankshafts, complete moving part assemblies, oil, water, fuel feed and injection pumps etc. These exchange units have been repaired in accordance with modern production methods and guarantee a satisfactory performance. Clean and test all parts and assemblies which have been removed (see testing and repairing operations). Damaged components such as screws, nuts, washers, lockwashers etc. must be checked whether they are fit for re-use; replace if necessary. They must not be reinstalled if damaged. Gaskets, sealing rings, locking plates, split pins etc. must always be replaced. Special cleanliness and care is necessary during the assembly and handling of reconditioned parts. A small damage on the surface of a ground shaft e.g. can cause the sticking of a bearing or other damages. Therefore, it is necessary before the assembly to check all ground and accu- rately machined parts for possible subsequent damages, which have to be repaired. It is also imperative to observe absolute cleanliness when assembling, Repair size specifications for the remachining of the cylinder bores, the crankshaft journals and pins and the camshaft bearing pins, as well as its bearings and the valve tappets allow proper overhauls of the engines. The data and specifications given in the tables are obligatory for all our repair shops. In addition to the usual equipment an engine assembly trestle should be available in repair shops where mojor repairs are carried out. An assembly trestle is necessary, because by using some most disassembly and assembly operations can be carried out considerably faster, easier and cleaner. The engine can be turned in the assembly trestle thus giving free access to all ports of the engine. Parts which cannot be removed and installed in the vehicle, e.g. pistons, connecting rods, crank- shaft ond camshafts should always be removed and installed in the assembly trestle The Engine Assembly Trestle BE 10488/1-6 can not only be used for the diesel engine Model OM 636 and OM 621 but also for all of our other passenger car engines. The only change required is to exchange the supporting arms and fixing bors (see Figure 00-20/1). 00-20/317. Removal and installation of pistons and connecting rods (see Job No. 03-11) 18. Disassembly and assembly of cylinder crankcase (see Job No. 01-25). 19. Removal and instollation of front seal ring for crankshaft, engine not removed (see Job No. 03-3), 20. Removal and installation of double roller chain, with assembled engine (see Job No. 05-27}, C. General The engine should only be removed for a general overhaul if a bearing has been damaged or if it has been determined beyond doubt that an excessive oil consumption or decrease of output is due to faulty pistons and cylinders etc. (see Job No. 0-10). In addition to special knowledge and experience, special machine tools, measuring instruments, gauges and special devices are needed for the testing and repairing of engines, as it is described in the following Job Numbers. In the interest of the customers we therefore recommend utilizing the possibility os far as possible of exchanging complete engines (replacement engines) or individual components, such as cylinder crankcases, crankshafts, complete moving part assemblies, oil, water, fuel feed and injection pumps etc. These exchange units have been repaired in accordance with modern production methods and guarantee a satisfactory performance. Clean and test all parts and assemblies which have been removed (see testing and repairing operations). Damaged components such as screws, nuts, washers, lockwashers etc. must be checked whether they are fit for re-use; replace if necessary. They must not be reinstalled if damaged. Gaskets, sealing rings, locking plates, split pins etc. must always be replaced. Special cleanliness and care is necessary during the assembly and handling of reconditioned parts. A small damage on the surface of a ground shaft e.g. can cause the sticking of a bearing or other damages. Therefore, it is necessary before the assembly to check all ground and accu- rately machined parts for possible subsequent damages, which have to be repaired. It is also imperative to observe absolute cleanliness when assembling, Repair size specifications for the remachining of the cylinder bores, the crankshaft journals and pins and the camshaft bearing pins, as well as its bearings and the valve tappets allow proper overhauls of the engines. The data and specifications given in the tables are obligatory for all our repair shops. In addition to the usual equipment an engine assembly trestle should be available in repair shops where mojor repairs are carried out. An assembly trestle is necessary, because by using some most disassembly and assembly operations can be carried out considerably faster, easier and cleaner. The engine can be turned in the assembly trestle thus giving free access to all ports of the engine. Parts which cannot be removed and installed in the vehicle, e.g. pistons, connecting rods, crank- shaft ond camshafts should always be removed and installed in the assembly trestle The Engine Assembly Trestle BE 10488/1-6 can not only be used for the diesel engine Model OM 636 and OM 621 but also for all of our other passenger car engines. The only change required is to exchange the supporting arms and fixing bors (see Figure 00-20/1). 00-20/3Figure 00-20/2 l 1 Bradt 2 Fining sods in ong bloc Figure 00-20/1 2 Recelvng box lor screws ond small pots 3 Leaing dovio of rear braset Putting Engine into Assembly Trestl 1. On OM 636 remove fan support if applic- able or on engines without fan support unscrew the mounting angle of the front engine support. Furthermore, on these engines the fan should be removed from the belt pulley. Attach the front bracket (1) fo the two fixing studs (2) (Figure 0020/2}. 2. Then secure the rear bracket (1) to the fixing studs (2) (Figure 00-20/3). 3, Put oil fo the bearings of the brackets and place engine in assembly trestle (see Figure 00-20/1), Note: As a safety measure and to allow locking of engine in 4 different positions a locking device (3) has been installed, which Figure 00-20/3 must engoge properly in the locking disc + hea weer (see Figure 00-20/1 and 00-20/3). 2 Fring std i erombcose 00-2014Technical Data for Engine OM 636 General technical data on vehicle and buil-in engines OM 636 3. Technical directions for built-in engines OM 636 Goneral performance data on vehicle and built-in engines OM 636 Fuel consumption data on vehicle and built-in engines OM 636 General table with type data, design versions, deviations in respect to stendard engine, copecities, and special performance data of OM-6%6- engines. mone> A. General Technical Data on Vehicle and Bi in Engines OM 636 Principle ssseecssesssseee a sssses Diesel pre-combustion chamber, end-to-end scavenging Operstion .oeecseesseeeee : . four-stroke Number of eylinders 4 Firing order (cylinder 4 ot flywheel) .. re 1-3-4-2 Direction of rotation ...eccsccsssseeesesseeee

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