GE

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Doc No. GEK−76681, Rev. −

Transportation
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7S1512 Turbocharger,
Inspection and Service
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GEK−76681, 7S1512 Turbocharger, Service and Inspection

© 2008 General Electric Company. All rights reserved. The information contained in this
publication is the property of General Electric Company and is disclosed in confidence. This
publication is intended for use by GE customers solely for purposes of operating and performing
routine maintenance of purchased or licensed GE products, and it shall not be reproduced,
redistributed, retransmitted, translated, abridged, adapted, condensed, revised or otherwise
modified, in any form, in whole or in part, or used for any other purpose, or disclosed to third
parties, without the express written consent of GE.

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GE and Customer agree that the information contained herein does not purport to cover all details

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or variations in GE products or to provide for every possible contingency with installation, operation
or maintenance. Should further information be desired or should particular problems arise that are

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not covered sufficiently for the user’s purposes, the matter should be referred to General Electric

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Company. Any applicable Federal, State or local regulations or company safety or operating rules
must take precedence over any information or instructions given in the Technical Documentation.

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GE has no obligation to keep the material up to date after the original publication.
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GENERAL ELECTRIC COMPANY EXPLICITLY DISCLAIMS ALL WARRANTIES OF ACCURACY,
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MERCHANTABILITY OR FITNESS FOR ANY PURPOSE IN CONNECTION WITH THIS PUBLICATION AND
USE THEREOF.
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If you are not an authorized recipient of this publication, you are hereby notified that any perusal,
use, distribution, copying or disclosure is strictly prohibited. If you have received this publication in
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error, please immediately return to GE at the following address: GE Transportation, Technical

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Publications Department, Building 14, 2901 East Lake Rd., Erie, PA 16531.
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 7S1512 Turbocharger, Inspection and Service, GEK−76681

CONTENTS
Page
1. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.2. RELATED PUBLICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.3. SAFETY INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
1.4. MODEL DIFFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. CONTROL AND INDICATORS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. FUNCTIONAL DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.1. TURBOCHARGER ASSEMBLY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
3.2. SYSTEMS INTERACTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. SCHEDULED MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

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4.1. GENERAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

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4.2. INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

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5. REMOVAL AND REPLACEMENT PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

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5.1. TURBOCHARGER REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.2. TURBOCHARGER INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

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5.3. OPERATIONAL CHECK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

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6. SUMMARY DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1. DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.2. TORQUE VALUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
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1. GENERAL INFORMATION
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1.1. INTRODUCTION
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This publication covers inspection and scheduled maintenance procedures the 7S1512 turbocharger. Figure 1
shows the compressor end, and Figure 2 shows the turbine end. Overhaul procedures are described in GE publication
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GEK−76682, 7S1512 Turbocharger, Overhaul. The General Electric 7S1512 turbocharger is a centrifugal air com-
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pressor (blower) powered by an axial−flow turbine driven by the energy in the engine exhaust gases prior to their dis-
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charge to the atmosphere.

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The following items are discussed in this publication:

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1. Turbocharger Assembly including:

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a. Turbine Casing Assembly

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b. Rotor Assembly

c. Turbine Inlet Assembly

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d. Blower Casing Assembly

1.2. RELATED PUBLICATIONS

S GEK−76882, 7S1512 TURBOCHARGERS, REPAIR AND OVERHAUL
1.3. SAFETY INFORMATION
Safety precautions which must be observed when working on the Turbocharger appear throughout this publication.
WARNINGS indicate the potential for personal injury, and CAUTIONS indicate the potential for equipment damage.

1.4. MODEL DIFFERENCES

There are two models covered in this publication for the 7S1512 Turbocharger:

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GEK−76681, 7S1512 Turbocharger, Service and Inspection

TURBINE WATER DISCHARGE

CASING BLOWER TURBINE OPENINGS
CASING CASING
AIR DISCHARGE
OPENING

TURBINE NOSE
INLET PIECE
CLAMP
RING

ROTOR
ASSEMBLY NOZZLE
RING

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MOUNTING
FEET

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EXHAUST GAS
INLET OPENING
AIR INTAKE TURBINE INLET

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OPENING FLANGE

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E−40811A E−40812

Figure 1. Model 7S1512 Turbocharger, Figure 2. Model 7S1512 Turbocharger,

Compressor End.
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S 7S1512A1 − Base Model
S 7S1512A2 − Different nozzle ring
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2. CONTROL AND INDICATORS

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There are no controls or indicators present on this equipment.

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3. FUNCTIONAL DESCRIPTION
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3.1. TURBOCHARGER ASSEMBLY

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The compressed air produced by the turbocharger serves two purposes:

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1. Compressed combustion air contains more oxygen per unit volume than air which is naturally aspirated (drawn
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in by piston action). Compressing the air increases the power of the engine, since more fuel can be burned on
each power stroke. Thus more power can be produced by a given engine displacement.
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2. During the latter part of the exhaust stroke and continuing into the early part of the intake stroke, there is a
period in the cycle when both intake and exhaust valves are open. This is called the valve overlap. During the
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overlap period, compressed air entering the combustion chamber expels spent exhaust gases and cools the
piston and cylinder parts. Exhaust gas temperature is also lowered by the cooler intake air during the overlap
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period.

3.1.1. Turbine Casing Assembly

The turbine casing assembly includes the turbine casing, bearings and seals. The casing (Figure 4) has four
mounting feet which are bolted to the engine forward end cover. All other sub−assemblies and parts are secured to, or
are mounted in, the turbine casing.

3.1.2. Rotor Assembly

The rotor assembly (Figure 5) comprises the turbine disk assembly, compressor wheel assembly, shaft, stud,
thrust collar, cap, key and nut. The rotor assembly rotates in the bearings of the turbine casing assembly.

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 7S1512 Turbocharger, Inspection and Service, GEK−76681

SEAL−AIR
CLEAN−OUT PASSAGE PIPE PLUG FOR
FLANGES (TO BLOWER LUBRICATING
AND SEALS CASING) OIL PASSAGE

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CLEAN−OUT

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COVER AND
GASKET

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BEARING

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LOCATING
DOWEL
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Figure 4. Turbine Casing, Turbine End.
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TURBINE ROTOR ASSEMBLY SHAFT

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CAP
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STUD
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LOCKNUT
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TURBINE
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DISK COMPRESSOR WHEEL

ASSEMBLY ASSEMBLY

E−40813A

Figure. 5. Rotor Assembly.

TURBINE DISK ASSEMBLY

E−44456

Figure 3. Turbocharger Components.

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GEK−76681, 7S1512 Turbocharger, Service and Inspection

3.1.3. Turbine Inlet Assembly

The turbine inlet assembly (Figure 6) includes the turbine inlet flange, nozzle ring, nozzle ring retainer, turbine
shroud and nose piece. The assembly is mounted in the turbine end of the turbine casing. The round flange is secured
to the turbine casing by a clamp ring, correctly oriented by four keys.

INLET

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NOZZLE
RING

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NOSE
PIECE

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RETAINER

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NUT
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BOLT
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SHROUD
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E−45635
NUT BOLT

Figure 6. Turbine Inlet Assembly.

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3.1.4. Blower Casing Assembly

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Included in the blower casing assembly are the blower discharge casing (Figure 7), blower inlet and diffuser. The
assembly is secured to the compressor end of the turbine casing. The inlet is connected to the supply of filtered engine
combustion air. The two outlets are joined by turbocharger discharge pipes to the intercoolers and then to the air
intake manifolds.

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 7S1512 Turbocharger, Inspection and Service, GEK−76681

DIFFUSER BLOWER
BLOWER
CASING CASING A
DIFFUSER

BOLT

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PIPE
PLUG

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BOLT
PIPE
PLUG
PIPE E−45636

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SECTION A−A gi nt PLUG A

Figure 7. Turbocharger Blower Casing.

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3.2. SYSTEMS INTERACTION

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The turbocharger is connected to, and is a part of, the following systems:
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3.2.1. Lubricating Oil

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Lubricating oil is taken from the engine main header supply at the front of the forward end cover. It first passes
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through an orifice in the flange connected to the cover. This orifice controls the rate of flow to the turbocharger. Oil
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flows through a pipe and is delivered to a connection point in the top of the turbine casing. Here the oil again passes
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through a final metering orifice (Figure 8). Drilled holes conduct oil to the two bearings. After lubricating and cooling
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the bearings, oil then flows by gravity through passages in the turbine casing, through a drain pipe down to the forward
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end cover, and back to the engine crankcase.

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ORIFICE

E−29352

Figure 8. Metering Orifice − Do NOT Remove Drilled Plug.

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GEK−76681, 7S1512 Turbocharger, Service and Inspection

3.2.2. Exhaust Gas

Exhaust gases are conducted to the turbine end of the turbocharger by the exhaust manifold. The gases pass
through a nozzle ring which directs them at the turbine blades (in the rotor assembly) to get the best utilization of the
energy in the gases. After causing the turbine rotor to rotate, the spent gases enter the turbine casing and pass
through the exhaust stack to the atmosphere.

3.2.3. Engine Air

Engine air is drawn through a series of screens, inertial cleaners and filters to the turbocharger compressor . The
compressor wheel − as its name implies − compresses the air and discharges it at high velocity into the diffuser. The

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diffuser reduces the velocity and increases the pressure before delivering the air to the blower casing. The blower

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casing, in turn, directs the compressed air to the two blower−casing outlets. Because the air is heated during com-

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pression, it must then be cooled by passing it through the intercoolers. This increases its density before delivery
through the intake manifolds to each cylinder for combustion and cooling.

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3.2.4. Cooling Water

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Water is discharged by the water pump through passages in the forward end cover to two holes in the top surface of

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this cover. These cover holes align with holes in the two rear mounting feet of the turbocharger. Water is circulated
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through internal passages in the turbine casing. After cooling the turbine casing, the water is discharged through two
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holes in the top rear portion of the turbine casing. Water then returns to the water system through a header.
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3.2.5. Seal Air

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In addition to the other four systems, the turbocharger has another, self−contained air system, called the seal air
system. The seal air system uses a small portion of the pressurized air produced by the compressor wheel, delivering
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it to the outboard side of both oil seals. This pressurized air acts as a barrier, minimizing the loss of oil through the
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seals.
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Seal air performs two additional functions: (1) It provides some cooling of the turbine disk assembly, and (2) it pro-
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duces a force on the face of the turbine disk which partially counter−balances the forces produced by the engine ex-
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haust on the turbine blades and the thrust produced by the compressor. This reduces the load on the turbine end thrust
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bearing.
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4. SCHEDULED MAINTENANCE
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4.1. GENERAL
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When mounted, the turbocharger is a difficult piece of equipment to check quickly. The turbocharger is frequently
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judged to be faulty on the basis of trouble reports or on the basis of symptoms observed while the diesel engine is
running during the inspection process. While the symptom noted could signify a defective turbocharger, frequently the
same symptom also can apply to other faults. Refer to TABLE 1 for examples of symptoms indicating multiple faults.

4.2. INSPECTION
The preferred method of qualifying a turbocharger for continued service is to observe it (and its effects) while load−
testing the diesel engine. Load−testing should only be performed after first establishing the following items are func-
tioning and correct:

1. EFI system operating properly. For units with mechanical fuel injection, check the following:

a. Fuel−oil injection pump racks − correctly set and equal

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 7S1512 Turbocharger, Inspection and Service, GEK−76681

b. Fuel−oil injection pumps − properly timed

c. Fuel linkage − must move freely

2. Fuel−oil injection pumps and nozzles − all must function

3. Air intake and exhaust manifolds − no leaks

4. Cylinder valve tappet clearance − correctly set

5. Fuel−oil filter and engine air filters − clean

6. Excitation circuits − must be in good order and capable of being adjusted.

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When under FULL LOAD and in Notch 8, observe the turbocharger (intake manifold) air pressure, color of exhaust

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gases and governor load control pot action; and check the turbocharger for oil and water leakage and mechanical

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distress. Use TABLE 1 to identify faulty turbochargers or other system components.

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When it is not possible to test the engine under load, perform the following turbocharger checks with the diesel

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engine shut down and the muffler removed:

1. Working down through the stack, use a flashlight and a mirror positioned to observe the turbine disk blades

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(Figure 9). While observing the blades, use a hook tool − made from 0.125−in. (3−mm) diameter wire − to lift
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and rotate the rotor through one complete revolution. Examine all blades for possible damage caused by for-
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eign material, and check the rotor for free rotation. Doing this will often break up carbon buildup (which causes
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reduced rotor speed) and allow continued use of the turbocharger.

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APPLY HOOK TOOL TO FACE OF

TURBINE DISK TO ROTATE ROTOR EXHAUST
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GAS OUTLET
PASSAGE
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ROTOR FLASHLIGHT
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ROTATION
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ADJUSTABLE
MIRROR
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E−23320

Figure 9. Inspecting Turbine Blades

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With Stack Or Muffler Removed.

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2. If possible, remove the clamps and flexible duct from the compressor end of the turbocharger (Figure 12).
Remove the air filters. Examine the compressor wheel for damage or distress. Manually turn the rotor, and
note that the rotor is free to rotate. Set up a dial indicator and move the rotor − as required − to check the thrust
clearance. Refer to DATA Section for limits.

NOTE: The thrust clearance given in DATA Section refers to the tolerance when NEW. It is almost impos-
sible to perform a valid thrust clearance check if the original clearance is unknown. If original clearance
is known, wear of 0.002 in. (0,05 mm) indicates the bearings should be replaced. If original clearance is
unknown, the only way to determine bearing condition is to disassemble the turbocharger, measure the
thrust clearance and inspect the bearings. Loss of thrust clearance is just as important as excessive
thrust clearance. Loss of thrust clearance indicates seal plugging and fouling.

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GEK−76681, 7S1512 Turbocharger, Service and Inspection

3. Look for evidence of rubbing and check the inducer tip clearance to be sure it is within the values given in DATA
Section. Clearance values obtained at the 6 o’clock position which are less than minimum at either the turbine
or compressor end indicates damaged bearings.

4. Check for plugged seal−air passages. Check the internal passages by applying shop air at the pipe plug on the
upper portion of the turbine casing (Figure 7). If passages are clear, the sound of escaping air should be heard
at the stack outlet and compressor end. If internal passages are plugged, the turbocharger must be changed
out.

5. Check visually for evidence of mechanical damage, excessive heat and water leaks.

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 7S1512 Turbocharger, Inspection and Service, GEK−76681

TABLE 1. TURBOCHARGER SYMPTOM−BASED TROUBLESHOOTING.

Crew Report Actual Possible Cause of
or Symptom Turbocharger Fault Turbocharger Fault Other Possible Faults
Black smoke out Rotor not turning Rotor damaged by foreign ob- Fuel−oil injection pumps not
stack Rotor turning at re- ject properly timed
(steady−state) duced speed Excessive carbon build−up be- Faulty fuel−oil injection pumps
tween turbine seal and disk and/or nozzles
Failed rotor bearings Excessive carbon build−up in
Failure of rotor turbine disk or cylinder air intake ports
compressor wheel Dirty intercoolers

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Compressor wheel or turbine Plugged engine air or fuel filters

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disk rubbing

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Leakage in air−intake manifold

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or exhaust manifold
Faulty excitation circuit adjust-

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ments or components

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Not loading or low Rotor not turning Rotor damaged by foreign ob- Dirty or plugged fuel−oil filter
on power Rotor turning at re- ject Fuel pump racks set incorrectly
duced speed
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tween turbine seal and disk set incorrectly
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Failed rotor bearings Leak in air manifold line to gov-

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Failure of rotor turbine disk or ernor, intake or exhaust man-

compressor wheel ifold
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Compressor wheel or turbine Also, see faults listed above for

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disk rubbing “Black smoke out of stack”

Engine “souping” from pro-
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longed idling, especially low idle

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Blue smoke, and oil, Failed rotor bearings Pipe plug missing in upper cav- Worn or broken piston rings
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out stack and/or seals ity of free−end cover Cracked piston (crown)
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Wrong size orifice in lubricat- Scored cylinder liner

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ing−oil supply pipe

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Rotor unbalance
Seal air passage Prolonged operation of engine Prolonged operation of engine
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plugged with carbon in idle and lower speed notches in idle and lower speed notches
Labyrinth in turbine−
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end seal plugged

with carbon
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Low turbocharger Rotor turning at re- Excessive carbon build−up be- Leakage at air discharge el-
(intake manifold) air duced speed tween turbine seal and disk, bows or in air−intake manifolds
pressure causing rubbing Leakage in exhaust manifold−
(At Notch 8, FULL Defective rotor bearings Faulty gage
LOAD)
Compressor wheel or turbine Also, see faults listed above for
disk rubbing “Low on power”
Low turbocharger Possibly, no fault. Turbocharger (intake manifold) air pressure is not indicated until in
(intake manifold) air Notch 3 or 4 and above, and under load. There is no indication when in dynamic brak-
pressure (At less ing.
than Notch 8, FULL
LOAD)

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GEK−76681, 7S1512 Turbocharger, Service and Inspection

5. REMOVAL AND REPLACEMENT PROCEDURES

5.1. TURBOCHARGER REMOVAL

At the intervals stated in the Inspection and Maintenance Instruction − or when inspection establishes that a turbo-
charger is faulty − remove the turbocharger in the following manner, referring to Figures 10, 11 and 12:

COMPRESSION
COUPLING

LUBE−OIL
WATER DISCHARGE GRAVITY DRAIN
HEADER

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TURBINE

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INLET

08
CLAMP

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EXHAUST
CLAMP−RING LUBE−OIL
HALVES SUPPLY PIPE

10 or
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E−31709
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Figure 10. Typical Turbocharger Installation Details, Figure 11. Typical Turbocharger Installation Details,
Compressor End.
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Turbine End.
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CLAMPS (2 OF 8)
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FLEXIBLE
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ASPIRATOR HOSES
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FLEX-
IBLE
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DUCT
COOLING−WATER
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CLAMP (1 OF 2) FLOW CONTROL

VALVE
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CRANK- AIR DUCT

CASE
GE

BREATHER
(EXHAUST TURBOCHARGER
STACK)
E−24460

Figure 12. Typical Turbocharger Installation Details,

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Compressor End.
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1. Drain the cooling water system.

2. Remove the hatch over the turbocharger.
3. Disconnect the crankcase breather from the exhaust stack or muffler. Remove the three or four aspirator
hoses. Remove the exhaust stack or muffler.

4. Remove the intercooler support bar.

5. Remove the two compression couplings from the water discharge header.

6. Unbolt the clamp rings at the turbocharger and intercooler ends of both air discharge pipes. Slide the discharge
pipe assemblies into the respective intercoolers.

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 7S1512 Turbocharger, Inspection and Service, GEK−76681

7. Disconnect the exhaust manifold from the turbine inlet assembly as follows:

a. On single−pipe manifolds, unbolt and remove the upper and lower clamp−ring halves.

b. On dual pipe manifolds, support the transition casting by blocking underneath or suspending the casting
from the water header. Remove the bolts holding the transition casting to the turbocharger turbine inlet
flange.

8. Remove the clamps, flexible duct, and metal air duct from the compressor end of the turbocharger.

9. Disconnect and remove the lubricating−oil supply pipe, with orifice, at the free−end cover and at the turbine
casing.

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CAUTION: Be extremely careful to not get ANY foreign debris or objects in the lubricating−oil supply pipe

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or the turbocharger. Openings in the lubricating−oil system should be immediately plugged or covered.

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10. Disconnect and remove the lubricating−oil discharge pipe at the turbine casing and at the free−end cover.

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11. Remove the four mounting bolts which secure the turbocharger to the free−end cover.

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CAUTION: Before removing the turbocharger mounting bolts, ensure the turbocharger is securely held
by the crane.
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12. Use the lifter (Tool 147X1916−1) to remove the turbocharger from the engine. Slightly rock the turbocharger
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while lifting to free the rear feet from their locating dowels.
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CAUTION: Exercise care in removing the turbocharger so as not to damage the exhaust manifold.
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13. After positioning the turbocharger on the floor:

a. Remove the water discharge header and retain for the replacement turbocharger.
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b. If the turbocharger was removed because of a failure (and not for a periodic replacement), thoroughly ex-
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amine the turbocharger and DETERMINE THE REASON FOR THE FAILURE. Neglecting to do so may
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result in a repeat failure. If the failure was caused by foreign material, it is MANDATORY that all traces of
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this material be removed. It may be necessary to remove and clean the exhaust manifold, or it might be
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necessary to remove the air filters to clean and inspect the filter clean air plenum. Also inspect the inlet side
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of both intercoolers for foreign material.

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c. Apply protective covers and pipe plugs to all openings in the removed turbocharger. Apply new covers and
plugs or transfer from the replacement turbocharger.
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d. Remove the crankcase breather cover and clean the screen assembly. Refer to Lubricating−Oil System
Instructions.
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CAUTION: If the turbocharger is being replaced because of bearing failure, check the cavity in the top of
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the free−end cover when the screen assembly is removed. Ensure the pipe−tapped hole is fitted with a
pipe plug. Failure to plug this hole will result in loss of lubricating−oil supply to the turbocharger bear-
ings, and also could cause “oil out the stack.”

14. Remove the air discharge pipe assemblies from both intercoolers, and disassemble the O−rings and clamp
rings from the discharge pipes.

5.2. TURBOCHARGER INSTALLATION

If the turbocharger is being replaced as a result of failure and not for a periodic replacement, CORRECT THE
CAUSE OF THE FAILURE (if caused by foreign object damage, for example). Applying new gaskets and lockwash-
ers, install the turbocharger in the following manner, referring to Figures 10, 11 and 12:

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GEK−76681, 7S1512 Turbocharger, Service and Inspection

1. Assemble both turbocharger air discharge pipes to the respective intercoolers as follows:
a. Preassemble both discharge pipes by sliding two clamp rings (Part 128X1023−1) onto the pipes back−to−
back. The larger flat sides of the clamp rings should be facing outwards.
b. Coat four new green Viton O−rings (Part 115X1902−2) with high−temperature FS1292* grease (Part
147X2428), and apply one O−ring onto each end of both discharge pipes. The grease reduces the probabil-
ity of O−ring damage during installation, and provides high−temperature lubrication during operation.
NOTE: Do NOT use Part 115X1268 black O−rings on the air discharge pipes; they will not withstand the
higher air temperatures.
c. Slide both discharge pipes − with preassembled clamp rings and O−rings − all the way into the air inlet port of
the respective intercoolers.

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2. Remove all protective covers and the pipe plugs from the lubricating−oil inlet and, if so equipped, from the seal

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air inlets and the rain drain outlet of the replacement turbocharger. Ensure no foreign material remains in the
turbocharger.

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3. Pour some clean engine lubricating oil into the oil inlet near the top of the turbine casing, and rotate the rotor

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assembly several revolutions.

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4. Assemble the water discharge header to the turbine casing using new gaskets.
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5. Clean and deburr the mounting surface of the forward end cover. Apply a film of Lubriplate* Spray Lube “A”
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(Part 147X1614) to the locating dowels, and install new O−rings around the water supply openings.
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6. Using the lifter (Tool 147X1916−1), hoist the turbocharger and clean and deburr the mounting feet. Position the
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turbocharger to align the dowel holes in the rear feet with the locating dowels. Slightly rock the turbocharger
while lowering it onto the free−end cover.
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WARNING: Ensure the turbocharger mounting bolts are securely tightened before removing the crane
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hooks.
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CAUTION: Use care when installing the turbocharger to avoid damaging the exhaust manifold.
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7. Assemble the four mounting bolts using new lockwashers. Using a 250 lb.−ft. (339 Nm) torque wrench (Tool
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147X2252) and an adapter (Tool 147X2350), tighten the mounting bolts to the torque given in DATA Section.
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NOTE: By setting the wrench to 225 lb.−ft. (305 Nm), the actual torque obtained will be 425 lb.−ft. (576
Nm) − in the middle of the torque range.
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8. Wash and blow out all piping; then referring to Figure 10, assemble the piping in the reverse order used at
removal. Refer to Steps 9 and 10 under TURBOCHARGER REMOVAL Section.
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WARNING: Personnel performing cleaning operations must wear protective clothing, gloves and eye
protection to avoid injury. When using compressed air, observe all Railroad and Government Regula-
tions.

CAUTION: The lubricating−oil supply pipe must have an orifice in the flange that is connected to the free−
end cover, and must be of the correct size to assure correct lubricating−oil pressure and flow to the turbo-
charger bearings. The orifice is a 0.350 in. (8,89 mm) nominal diameter. Make certain there is also an ori-
fice plug at the oil inlet to the turbine casing. This is simply a hollow−head pipe plug with a nominal 0.230
in. (5,84 mm) diameter hole. Its purpose is to prevent excessive flow.

* Product of Dow Corning

* Product of Fiske Brothers Refining Company

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 7S1512 Turbocharger, Inspection and Service, GEK−76681

9. Assemble the rubber flexible duct, and secure with two clamps.

10. Connect the exhaust manifold to the turbine inlet assembly as follows.

a. Ensure all manifold−to−turbocharger bolt threads are clean. If necessary, wire brush the bolt threads and
re−tap the threaded holes. Apply high−temperature anti−seize thread compound (Tool 147X1640) to all
threads and to the washer face of the bolt heads.

b. Install a new gasket in the turbine inlet flange groove that is integral with the shroud.

c. For dual−pipe exhaust manifolds, bolt the transition casting to the turbine inlet flange, tightening the bolts to
the torque given in DATA Section.

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d. For single−pipe exhaust manifolds:

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1) Assemble the lower clamp−ring half, and secure with bolts and new lockwashers finger−tight. The joint
line of the clamp ring should be near horizontal.

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2) Assemble the top clamp−ring half, and secure with bolts and new lockwashers. Equalize the gaps at
the clamp−ring joint line, and alternately tighten the bolts to the torque given in DATA Section.

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11. Slide both air discharge pipes into the turbocharger discharge elbows, centering each between the turbochar-
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ger and respective intercooler. Apply high−temperature anti−seize thread compound to the three bolts for each
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clamp ring. Using flat washers, install all clamp ring bolts finger−tight. Then tighten all twelve bolts to the torque
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given in DATA Section.

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12. Using new gaskets, assemble the two compression couplings to the water discharge header.
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13. Install the exhaust stack or muffler, and secure with the special bolts and hardened flat washers. Tighten the
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bolts to the torque given in DATA Section.

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14. Assemble the intercooler support bar.

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15. Connect the crankcase breather pipe to the crankcase breather and to the exhaust stack or muffler. If so
equipped, connect the three or four aspirator hoses.
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16. Replace the hatch over the turbocharger.

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17. Fill the water system with properly treated water.

5.3. OPERATIONAL CHECK

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After the turbocharger work has been performed and the engine is running, listen near the turbocharger and the
exhaust stack for unusual noises, such as parts rubbing.
If possible, load the engine and observe that the turbocharger is performing its function. This will be evident by an
indication of pressure on the turbocharger air pressure gage. In general, pressure should be above 25 psi (172 kPa) in
Notch 8, depending on the engine model; and the stack should be clear. Check the turbocharger for water, oil, air and
exhaust leaks, and correct as necessary.

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GEK−76681, 7S1512 Turbocharger, Service and Inspection

6. SUMMARY DATA

6.1. DATA
English Metric
Turbocharger weight 1825 lb. 828 kg
Rotor End−Play:
New 0.012−0.021 in. 0,30−0,53 mm
Max. Worn 0.021 in. 0,53 mm
(See NOTE under INSPECTION, Step 2)
Turbine Blade Tip Clearance 0.022−0.036 in. 0,56−0,91 mm
Inducer Tip Clearance 0.024−0.038 in. 0,61−0,97 mm

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6.2. TORQUE VALUES

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Lb.−ft. Nm
Bolts, turbocharger mounting 400−450 542−610

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Bolts, discharge pipe clamp rings to turbocharger and intercooler 30−35 41−47

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Bolts, exhaust manifold to turbocharger 70−75 95−102
Bolts, stack clamping 55−60 75−81

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NEW 11−03, GMD (MCC)

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