Sad Service. Auol 3,3 | V8 TDI Engine - Mechanicals Design and Function Self-Study Programme 226 ron10 years of TDI - The history of the TDI 1989 Audi presented the first diesel-powered passenger car with direct injection in the Audi 100. The 2.5-Itr. 5 cylinder TDI developed 88 kW (120 bhp) and 265 Nm of é i] torque. A short while later, an 85 KW (115 bhp) version conforming to the US standard valid at that time was launched. This engine was installed in over 20% of the Audi 100/A6 models. 1991 saw the introduction of the four-cylinder 1.9-Itr. TDI developing 66 kW (90 bhp) and 202 Nm of torque in the Audi 80. od 1995 The performance-enhanced version of the 1.$-Itr. TDI developing 81 kW (115 bhp) and 235 Nm of torque came on the market. It was the first direct injection diesel to be equipped with a mapped exhaust gas turbocharger with variable turbine geometry (VTG). The 103 kW (140 bhp) version of the 2.5-Itr. engine developing 290 Nm of torque was presented together with the permanent four-wheel drive quattro. This combination of two typical Audi technologies was to become a meteoric success. 1997 Audi laid a yet another milestone with the V6 4-valve TDI. It was world's first six-cylinder direct injection engine diesel to be used in a passenger car. It is also the most powerful of the production TDIs, developing 110 kW (150 bhp) and 310 Nm of torque. Audi has revolutionised the popular conception of diesels with its TD! engines, proving that this engine concept can even compete with the petrol engine in terms of dynamics and driving enjoyment, with the added advantage of 30% lower fuel consumption and outstanding bottom- end torque. This engine therefore strikes a perfect balance between apparent opposites such as sporty driving on the one hand as well as eco-friendly mobility and long range on the other. Audi perfected these qualities, as exemplified by the five-cylinder TDI from 1989, with the V8 TDI Common RailIntroduction V8 TDI engine Specifications . Mechanicals Crankshaft type Piston . Conrod Cylinder head ....... Four-valve concept Toothed belt drive . Lubrication Oil circuit . we 15 Crankcase breather 2. 16 Cyclone oil separator se 17 Oil filter module 217 Cooling circ! Overview 18 Main cooling circuit . . s+ 20 Charge air cooling circuit we 21 Fuel cooling circuit .. ves 22 Hydraulic radiator fan 224 Air ducting Overview oes 26 Charging : 27 Vacuum chart... 000... cee eeee 2. 28 Charge air and exhaust gas cooling +. 30 Double-flow throttle valve..... - 32 Service Special tOOls oo... . 66 ceeeeeeeeeseeeeeeeeeeeee es 33 ‘Tho Self-Study Programme informs you about designs and functions. ‘The Self-Study Programme is not a Workshop Manual! Please refer to the relevant technical literature for all maintenance and repair instructions. Contents New! Important! Note! eA eead Introduction V8 TDI engine The new V8 TDI engine combines exceptional performance with high fuel economy and low exhaust emissions, not to mention extraordinary smoothness and a high standard of comfort. SSP226.001ns Code: AKF Type: V8 engine with 90° V angle and biturbocharging Displacement: 3328 cm? Power output: 165 KW (225 PS) at 4000 rpm Torque: 480 Nm at 1800 rpm Bore: 78.3mm ‘Stroke: 86.4mm Compression 18.0:1 265 kg Firing order: 1-5-4-8-6-3-7-2 Mixture Direct injection with preparation: Common Rail System Exhaust gas Biturbocharger with variable turbocharger: turbine geometry Exhaust gas treatment: Bank-specific exhaust gas recirculation with pre-and post- oxidation catalytic converters Conforms to exhaust emission standard EU Ill 560 200 kw 420m 165.80 Nm 450 150 400 15 350 100 2300 i 250 50 200 6 180000 -2000~~3000~——in 5000 ‘8SP226_002 = Torque (Nm) ——= Power output (kW) The maximum torque of 480 Nm is achieved at only 1800 rpm and remains constant at this high level up to an engine speed of 3000 rpm. Max. output is 165 at 4000 rpm, Engine code and engine number are located on cylinder 5 below the exhaust manifold mount. ‘SSP226_037Mechanicals SSP226_003This diagram can be ordered through Bertelsmann Distribution as a poster in AO format for a net price of DM 10,00. ‘© This offer is valid for Germany only. To order poster in export markets, please contact your importer. Order No.: 507.5317.01.00 SSP226_004Mechanicals == Wi ‘SSP226_005High ignition pressures build up in the area of, the main bearing and throughout the bearing block. In addition to the given strength criteria, the crankcase/main bearing joint also had to meet certain acoustic criteria. To meet these requirements, the crankcase for V8 TDI was split in the middle of the crankshaft and a composite construction was chosen for the main bearing part. The main bearing joint (four bolts per bearing) absorbs the high forces exerted on the bearings. The lateral connections of the individual bearing points produce a highly rigid frame which prevents longitudinal vibra- tion of the bearing seats. Piston The piston has a cooling duct for reducing the temperature in the ring area and at the rim of, the recess (refer to SSP 183). Awide piston recess is used in combination with a 6-hole injector. The oil sump has been raised up to the centre of the bearing. This separates the crankshaft bearing from the oil sump acoustically, minimising noise radiation. The forged crankshaft is made of tempered steel. Two conrods run on a single crank pin In a VB engine, with its typical 90°V angle crankshaft and 90° offset, this makes for a uniform spark gap. Piston recess of V8 TDI Cooling duet — Piston recess of V6 TO! ‘SSP226_007Mechanicals Conrod Through its trapezoidal shape, the contact surface of the conrod eye and piston hub at the piston pin is larger than the conventional joint between the piston and conrod. Combustion forces are distributed over a larger surface area, reducing conrod and piston pin stress. The high combustion pressures of approx. 160 bar are transmitted to the crankshaft via a "sputter bearing” on the conrod side, asin the ‘V6 TDI. Sputtering is the application of a bearing material using electrical energy. By accelerating the particles of the bearing material from positive to negative, the material is transferred onto the substrate in a highly compressed form at supersonic speed. This final wafer-thin, anti-friction layer has a high surface hardness and exhibits better wear resistance. 10 V6 TDI v8 TDI V6 TDI $9P226_010 — Enlarged contact surfaces Vacuum chamber Argon gas ions Vacuum pump Bearing cup mount High voltage / Bearing material ‘SSP226_011Cylinder head Spring clip Derived from the V6 TDI and provided with an additional cylinder, the cylinder head is of narrow construction due to the constraints on installation space. The intake camshafts are driven by the toothed belt and, in turn, drive the exhaust camshaft by means of helical gears. The valves are actuated via cam followers (refer to SSP 183). SSP226_012 SSP226_013 The injectors are secured by elastic spring clips. Thismakes a precisely defined and uniform load with low distortion possible whether the engine is cold or hot. The common rail injectors are installed in the upright position midway between the exhaust and intake valves. u12 Mechanicals The injectors are sealed off from combustion chamber by means of a sealing disc. Ifa leak occurs, excess combustion pressure can escape into the atmosphere along the duct. This prevents large amounts of gas flowing to the compressor side of the exhaust gas turbocharger via the crankcase breather and causing it to malfunction. Excess pressure relief in the event of leaks at the injector / SSP226_018 Sealing disc Cylinder head cover ; Sealing ring on injector The isolation of the cylinder head cover Elastomer Ay serves as soundproofing (refer to SSP 217). sealing lip \ The injectors are sealed by separate cover plates with an injection-moulded elastomer- sealing lip. During installation, the transitions from straight surfaces to curved surfaces have to be sealed with a special sealing compound (refer to Workshop Manual). $5P226_032Four-valve concept Filling duct Tumble duct Ny ‘Twin-pipe duct SSP226_015 The 4-valve arrangement known from the V6 TDI engine with two intake ports per cylinder (tumble duct and filling duct) two exhaust ports per cylinder (twin-pipe duct) central, upright injector position central combustion chamber rotated valve position for better thermodynamics was adopted unchanged. 13Mechanicals Toothed belt drive Camshaft gear wheel Camshaft gear The high-pressure pump drive is integrated in the toothed belt drive. The toothed belt guide was modified compared to the V8 5V engine for this reason, It requires an additional deflection pulley but does without a stabilising pulley. Use special tool 3458 of the V6 TDI to fix the camshaft (refer to Workshop Manual). 4 High-pressure pump ~~! Excentric roller SSP226.014 Installation positions need not be ‘observed when installing the high- pressure pump.Lubrication Oil circuit Cylinder bank 1 Cylinder bank 2 Vacuum pump limiting valve Restrictor camshaft Oil pressure C2 on retaining valve / \ Exhaust gas turbo-charger Exhaust gas turbocharger Oil filter module Filter element Oil sump Oil cooler S5P226_016 Bypass valves: Oil pressure control valve Duocentric oi! pump = Oil curve without pressure MEN ——_Oil curve with pressureLubrication Crankcase breather In charged diesel engines, so-called blow-by gases occur as a result of leakage flows at the piston rings. These gases are discharged from the combustion chamber and flow into the crankcase. They have to be burned for ecological reasons. Exhaust gas turbocharger Charge air cooter = g S = ‘ Blow-by gases Valve piston Turbulence caused by blow-by gases and crankshaft web “drag” | ‘SSP226_030 The oil spray drawn off the crankcase precipitates droplet by droplet in the evaporation line and flows back into the crankcase. 16Cyclone oil separator The blow-by gases are fed along a line into the oil separator from the inner V of the engine. The swirling movement of the gases inside the oil separator separates the oil from the gases because the oil exhibits inertia. The oil-free blow-by gases now enter in the intake duct upstream of the left turbocharger and are then burned. The membrane integrated in the cyclone filter cover is used to control the vacuum in the crankcase. If the suction capacity in the intake duct exceeds the pressure in the crankcase, the membrane closes the turbocharger suction port. This prevents oil from entering the intake duct. Oil filter module The oil filter module is largely identical to that used in the 4.2-litre petrol engine. The oil filter housing has been extended upwards by approx. 30 mm in order to absorb a larger quantity of oil and to mount a larger oil filter cartridge for long life service. Membrane To intake duct ‘SSP226.031 from crankcase Flow to intake duct closed SSP226.034 ‘SSP226_017 7Cooling circuit Overview‘SSP226_019 The cooling circuit is subdivided into three areas: = high-temperature — - main cooling circuit = low-temperature - charge air cooling circuit low-temperature - fuel cooling circuit 19Cooling circuit Main cooling circ The engine cooling and EGR cooling systems are integrated in the high-temperature circuit. EGR cooler return line EGR cooler supply line } \ Pilinder head / Heating return line front left “ / ‘tecti , Coolant temperature = /- Heating supply tine senders G2 and G62 | Permanent {fy | ventilation / / expansion \ \ \ / / tank top Cylinder head, rear right \ \ Water pump supply line NX \ BD Thermostat housing Fes \ Filling hose for fuel \ \ cooling circuit \ Expansion tank, bottom Main cooler vent Filling hose for charge air cooling circuit Main cooler return line {main cooling circuit) | \ \ ; Connection Cross-member with engine block \ connection Main cooler supply line ‘95226 020 (main cooling circuit) 20Charge air cooling circuit The charge air cooling circuit is connected to The charge air cooling circuit also has a low- the main cooling circuit by a filling hose and _ temperature area in the main cooler. has its own additional electrical coolant pump and an additional cooler (air - water). Charge air cooler return line Charge air cooler supply line / Bleeder hose Additional cooler | Additional coolant pump V188 Main cooler supply line (charge air cooling circuit) | | Main cooler return line (charge air cooling circuit) ‘SSP226_021 2Fuel cooling circuit It is important that the fuel enters the return line cooled, because of the high temperature which builds up when the diesel fuel is compressed (the temperature rises to approx. 1350 bar). The heat exchanger for diesel fuel is integrated in the return line, Heat exchanger for The increased temperature of the fuel is diesel fuel dissipated to the cooling water flowing 1 through the cooling circuit. The additional electrical coolant pump delivers the heated coolant back to the heat Vent screw exchanger through an additional cooler. \ The fuel cooling circuit is connected to the return line of the main cooling circuit along the filling hose, Filling hose Supply line Additional cooler Additional coolant pump V165 SSP226_022 The additional electrical coolant pump runs continuously after the engine is started. 22Vent screw to additional cooler \ \ / from additional \\ \W\ \\ \ \\ / coolant pump Fuel to tank / \\ \\ \\ \\ J\ Fuel from injectors SSP226_029 Fuel cooling (air) The fuel is cooled additionally by a specially shaped return line located on the underside of the vehicle. The aluminium profile provides a large cooling surface because of its shape. The radial longitudinal grooves in the interior of the return line are conducive to heat transfer from the fuel to the cooling profile. Cooling profile Vehicle me / a = ) Return line SSP226_035Cooling circuit Hydraulic radiator fan Ahydraulic radiator fan system is used in order to utilise of the heat balance fully. The system components include: ~ Tandem hydraulic pump — Solenoid valve for radiator fan control N313 — Radiator fan with hydraulic motor = Oil tank = Oil cooler Engine control unit J248 ‘Tandem hydraulic pump. Solenoid ~~ valve for radiatorfan Radiator fan with hydraulic motor Oil cooler ‘SSP226_008 24Driven by the ribbed V-belt, the tandem A regulating valve cycled by the engine hydraulic pump supplies the power control unit conveys a specific quantity of oil steering and the hydraulic fan with oil to the hydraulic motor in dependence upon pressure simultaneously. engine temperature and speed. Pressure connection _ Return for steering gear ‘$P226_009 _ a Pressure connection Solenoid valve for for hydraulic motor radiator fan control N313 The internal geared wheel connected directly to the fan is driven by this quantity of oil. The oil flows along the return line and into the intake line of the hydraulic tandem pump. Trochoidal internal —— geared wheel of hydraulic motor ~~~ Oil pump cover with pressure and discharge ducts ‘SSP226_023 SSP226_036 25671 Air ducting Overview Intake module with integrated Air inlet from air filter charge air cooling and EGR cooling N Charge pressure sender Hot-film air mass meter G70/G246 —— ya SSP226_028 Vacuum box for vane adjustment Exhaust manifold 26Charging Two small exhaust gas turbochargers with a variable turbine geometry are used in the V8 TDI engine for charging purposes. Advantage: Using a small turbocharger improves the bottom-end torque curve. The turbocharger controls the charge pressure through bank-specific air flow metering by means of two hot-film air mass meters, The variable guide vanes of the turbocharger are actuated by means of vacuum boxes activated by electro-pneumatic valves. To optimally utilise exhaust gas energy specifically in the warm-up period while ensuring that exhaust emissions conform to the EU III limit values, the manifolds for each cylinder bank are joined in a cloverleat pattern and are insulated from the outer skin of the body-shell by an air gap. The two independent air intake ducts are cooled by the turbocharger in a common intake module after the air is compressed. Each of these ducts supplies air to a single cylinder bank To be able to realise a highly compact engine design, the intake module was positioned in the inner V of the engine. In addition to ducting the intake air, the intake module contains a combined charge-air and EGR cooler module.. The turbochargers may be replaced individually.Air ducting Vacuum chartB c G2/G60 G28 G40 G70 G71 6246 J248 Nig. N75 N213 N274 N239 $SP226_027 Vacuum pump Brake servo Throttle valves Coolant temperature sender Engine speed sender Hall sender Air-mass flow meter Air-mass flow meter2 Diesel direct injection system control unit EGR valve, cylinder bank1 Solenoid valve for charge pressure control EGR valve, cylinder bank 2 Solenoid valve 2 for charge pressure control Intake manifold changeover valvesAir ducting Charge air and exhaust gas cooling Advantage: The charge air and EGR cooling systems are __The water-air cooling system achieves the combined in a single module comprising two same charge-air cooling effect with separate cooling circuits; the cooled air considerably less loss of charge pressure, downstream of the two throttle valves is fed Also, better efficiency is achieved in the into the engine bank by bank. reheating phase and when driving uphill. EGR valves Solenoid valve for N18/N213 throttle valve N239 EGR valve ~ y EGR valve EGR cooler ~ Charge air cooler Throttle valves ‘SSP226 024 30To reduce NO, and particle emissions still further, the exhaust gas recirculated in the V8 TDI is additionally cooled by an air-water cooler. EGR valves Exhaust gas Intake Intake pipe charge ai Intake pipe Cylinder 7 EGR cooling ‘SSP226_025 Cooling the charge air 31Air ducting Double-flow throttle valve The double-flow throttle valve is closed when the engine is shut down for a short period of time. Advantages: The engine does not run on after it has been shut down and no unburned fuel enters the cylinders (when the engine is restarted, fewer unburned particles are emitted). Throttle valve Charge pressure sender G71 ‘SSP226_026 Vacuum box for throttle valve positioning In normal position and at full throttle, the two throttle valves are fully open. If the EGR system is active, the valve moves into intermediate positions so the fuel mixes better with the induced air. 32Service Special tools ‘Shown below are the new specialtools and workshop equipment for the 3.3-Itr. V8 TDI engine. Special tool for valve removal Compression test adapter Pressure piece WW 541/6 V.A.G. 1763/5 Adapter for assembly fixture 2036/1 Setting gauge for camshaft retainer 3458 Test box for V6-TDI V.A.G 1598/30 33NotesNoteseee’ poy Peeverrertes ror Ws cece Perey Per eee) poet ore 226