D399, G399, D398, G398, D379, G379 ENGINES Caterpillar


Turbocharger

Usage:

Introduction


TURBOCHARGER CONSTRUCTION

1 Thrust ring.

2 Thrust bearing.

3 Thrust ring.

4 Spacer.

5 Compressor cover.

6 Clamp.

7 Shaft.

8 Nozzle.

9 Turbine back plate.

10 Wear washer.

11 Sleeve.

12 Turbine housing.

13 Shims.

14 Nut.

15 Compressor impeller.

16 Turbine wheel.

17 Ring seals.

18 Ring seals.

19 Retaining ring.

20 Insert.

21 Seal.

22 Oil deflector.

23 Bearing housing.

24 Vent tube.

25 Oil drain hole.

26 Bearings.

27 Oil thrower.

The turbocharger is designed to increase diesel engine power output. The turbocharger utilizes diesel exhaust gases to drive the compressor impeller (15) for supercharging the diesel engine.

Turbine wheel (16) is located in the turbine housing and is permanently secured to one end of shaft (7). The impeller is secured to the other end of the shaft by nut (14) to form an integral rotating assembly. To assure reliability and freedom from vibration, all parts of the rotating assembly have been carefully dynamically balanced. The compressor impeller can be replaced separately.

Vent tube (24) vents the oil cavity to the crankcase. Venting this cavity promotes draining of oil from bearing housing, and therefore away from the seals, thus reducing the work-load imposed on the seals.

The rotating assembly is supported by two full floating pressure lubricated bearings (26). Filtered engine oil is supplied to the bearings through passages in the housing to lubricate the shaft bearings (26) and thrust bearing (2). This oil aids in removal of excessive heat. Oil returns from turbocharger to the crankcase through an external tube at (25). Thrust loads are absorbed by stationary thrust bearing (2) and rotating thrust rings (1) and (3). Oil deflector (22) contains and routes the oil thrown from the shaft and thrust rings back to drain opening (25).

Ring seals (17) and (18) on either end of the shaft prevent oil from escaping the bearing housing.

Beside housing the turbine wheel, the turbine housing acts as a chamber for exhaust gases from the diesel engine. Gases are directed through the turbine housing into contact with the turbine blades by the nozzle (8).

Shims (13), located between impeller (15) and sleeve (11), adjust the impeller-to-cover clearance.

Always handle the turbocharger carefully to avoid damage to any of its components.

Altitude Operation

Maximum turbocharger speed is determined by the rack setting, the high idle speed setting and the altitude at which the engine is operated. The rack setting has been set to permit the engine to be operated at the altitude given on the warning plate on the instrument panel or valve cover. The high idle speed setting is not the same for all altitudes. If the high idle speed or the rack setting is greater than specified for the altitude at which the engine is operated, serious damage to engine or turbocharger parts can result.

The maximum altitude at which the engine can be operated is specified on the altitude warning plate located on the valve cover or instrument panel. The governor housing and turbocharger are sealed to prevent serious engine damage due to operation of the engine with incorrect settings or turbocharger nozzle. Changes to the turbocharger, rack setting, or high idle speed should be made only by a Caterpillar dealer serviceman.

The engine can be operated at a lower altitude than specified on the warning plate without danger of engine damage, but with slightly less than maximum performance. When operated at a higher altitude, the rack setting and high idle speed setting must be changed only by a Caterpillar dealer serviceman. After making any changes, stamp the new altitude limit on the altitude warning plate.

Also, stamp the new high idle, full load speed, and rack setting on the governor warning plate. Reseal the governor housing for continued protection.

Sealing Of The Turbocharger

The turbocharger is sealed at the factory. Factory installed seals are identified by the letters CTCO. Dealer's sealing tool will impress the letters DLR on the seals.


TURBOCHARGER FACTORY SEAL
1-Seal.

Checking Bearing Clearance

A quick check of bearing condition can be made without disassembling the turbocharger. This can be done by inspecting the compressor impeller, turbine wheel, turbine housing and compressor cover. If there is no indication of either the impeller rubbing the compressor cover or the turbine wheel rubbing the turbine housing, the bearing clearances are generally satisfactory.

A more reliable check of bearing condition can be made only when the turbocharger is disassembled and the bearings, shaft journal and housing bore diameter can actually be measured. See the topic, SPECIFICATIONS, for these diameters.

While the turbocharger is disassembled, carefully check the back surface of the compressor impeller for sign of contact with the cover. Contact in this area indicates a worn thrust bearing or thrust rings.

Checking Turbocharger Shaft End Clearance

See the topic, SPECIFICATIONS, for normal and permissible shaft end clearance (axial movement). End clearance is checked with a dial indicator, either on the engine or off the engine. If the permissible clearance is exceeded, the turbocharger should be reconditioned.

Disassembly Of The Turbocharger

Compressor Cover and Turbine Housing Removal and Installation

1. With all turbocharger openings covered, wash exterior of the turbocharger thoroughly with a nonflammable fluid before disassembly.

2. Prior to disassembly, mark compressor cover (1), turbine housing (5) and bearing housing (2) to insure correct positioning at assembly.


PREPARING TO REMOVE COMPRESSOR COVER AND TURBINE HOUSING
1-Compressor cover. 2-Bearing housing. 3-Clamp. 4-Bolts (eight). 5-Turbine housing.


NOTICE

Use caution when removing turbine housing to prevent turbine nozzle (7) from falling.


3. Lift nozzle (7) from turbine back plate (6).


REMOVING NOZZLE
2-Bearing housing. 6-Turbine back plate. 7-Nozzle.

4. Before installing the compressor cover and turbine housing, see the topic, CLEANING AND INSPECTION.

5. Complete the assembly. Turn the impeller by hand to be certain there is no rubbing or binding within the turbocharger.

Rotating Parts

Before disassembly of the rotating assembly, measure shaft end clearance as previously described. If clearance is excessive, or if either the turbine wheel or impeller has rubbed against the housing or cover, replace the bearing and/or thrust bearing, and thrust rings. Bent impeller blades require replacement of the impeller. Turbine blades, which are noticeably bent require replacement of the turbine and shaft assembly.

Bearing failure can damage the shaft journals and/or thrust bearing or rings. Excessive wear or roughness renders the shaft unsuitable for reuse. If the shaft journals measure less than the specified diameter, install a new turbine and shaft assembly. Visual inspection and experience are the only ways to determine when the roughness of shaft prohibits reusing the assembly. New bearings will not correct excessive wear on the thrust bearing or thrust rings.

Installing new bearings does not eliminate necessity of inspecting and cleaning rotating parts.


FIXTURE


FIXTURE ADAPTER

1. Assemble fixture adapter (2) to fixture (4). Place bearing housing (1), containing the rotating parts, on fixture adapter with turbine wheel down as illustrated.

2. Remove the nut. The rotating assembly can be held stationary by wrench (3) as shown.


WRENCH


NOTICE

Take care to prevent any distortion of the blades. It is also recommended that a double universal joint be used to prevent possible bending of the shaft.



REMOVING NUT
1-Bearing housing. 2-Fixture adapter. 3-Wrench. 4-Fixture.


SUPPORTING SCREW

3. Thread supporting screw (5) into the base of the fixture to support the turbine wheel and shaft after it is pressed from the impeller. Leave a space between the end of the screw and the turbine wheel equal to, or slightly greater than, the thickness of the impeller. This will allow unobstructed pressing and prevent the turbine wheel from being damaged.

4. Using a press and a pin, press the shaft and turbine wheel from the impeller hub as shown.


PRESSING SHAFT AND TURBINE WHEEL FROM IMPELLER
5-Supporting screw.

5. Remove the impeller and shims.

6. Remove the turbine wheel and shaft.

7. Measure the shaft journal diameters and inspect the journals for roughness. If the journal diameters are less than specified, the shaft and turbine assembly must be replaced. See the topic, SPECIFICATIONS, for correct dimensions.

8. Inspect the ring seals and measure their thickness. Measure the width of the ring seal grooves. See the topic, SPECIFICATIONS.

Bearing Housing


REMOVING TURBINE BACK PLATE
1-Back plate. 2-Snap ring. 3-Bearing housing.

1. Invert bearing housing (3).


PREPARING TO REMOVE INSERT
4-Retaining ring. 5-Insert.

NOTE: Use two 10-24 NC machine screws to remove insert (5) from housing (3).


REMOVING INSERT
5-Insert. 6-Bolts (three). 7-Oil deflector.

2. Remove sleeve (9) from insert (5).


REMOVING SLEEVE
5-Insert. 8-Ring seals. 9-Sleeve.

3. Inspect seals (8) and the groove in sleeve (9). See the topic, SPECIFICATIONS.


THRUST BEARING REMOVAL
10-Thrust ring. 11-Thrust bearing. 12-Spacer. 13-Thrust ring. 14-Spacer.

4. Remove bearing (15) from housing (3).


BEARING REMOVAL
3-Bearing housing. 15-Bearing. 16-Snap rings (three). 17-Bearing and wear washer.

5. Inspect and measure thrust rings (10) and (13), thrust bearing (11), the bore in bearing housing (3), bearings (15) and (17). See the group, SPECIFICATIONS. Replace wear washer if it is excessively worn. Bearing wear is satisfactory if the turbine and/or wheel have not rubbed the housing.

Cleaning And Inspection

Inspect all rotating parts for binding and damage caused by rubbing on adjacent parts.

Wash all parts with cleaning solvent and dry thoroughly. Use a piece of wood to clean the carbon from the turbine housing and the nozzle.

The turbine wheel must be cleaned with cleaning solvent to dissolve the carbon. When hard carbon deposits are formed, soaking in a solvent-type cleaner for an hour or more is required. The loosened particles must all be scraped off with a stiff brush or a specially shaped piece of wood and, if necessary, the whole process repeated. If the wheel is covered with soot only, washing with a stiff brush and cleaning solvent and then rinsing with clean water will be sufficient.


NOTICE

The rotating components must be thoroughly cleaned in order to maintain critical balance of the unit. Do not use a wire brush or wheel.


Assembling Turbocharger

Keep out dirt and foreign material. Be sure all parts are clean.

Bearing Housing

Install snap ring (4), wear washer (1) and bearings (3) as shown. Lubricate the bearings before installing them.

NOTE: Earlier bearings (2) were interchangeable. Later (and parts service for earlier) are not. Install the bearing without the groove nearest the turbine.


NOTICE

Do not scratch or damage the housing bore when installing snap ring (4). Install the rings with the flat side toward its bearing.



BEARING INSTALLATION
1-Wear washer. 2-Bearing housing. 3-Bearings. 4-Snap rings.


BACK PLATE INSTALLATION
2-Bearing housing. 5-Back plate. 6-Snap ring.

Install back plate (5) on the bearing housing (2) and secure with snap ring (6).

NOTE: The beveled-type snap ring (6) must be installed with the flat side toward the back plate. Make certain the ring is secure in the groove.

Rotating Parts

1. Lubricate the ring grooves and use fabricated ring expander sleeve (1) to install the two ring seals on the shaft.


DETAIL FOR FABRICATING RING EXPANDER SLEEVE

2. Remove the sleeve and rotate the rings until the gaps are 180° apart.


INSTALLING RING SEAL
1-Ring expander sleeve.

3. Center the ring seals on the shaft with the gaps 180° apart and insert the shaft into the turbine end of the bearing housing. If the rings do not enter the housing easily, remove the shaft and re-center the rings.

4. Using fixture adapter (5), place the bearing housing (2) and shaft (3) on fixture (4). Support the shaft with support screw (6).


SHAFT INSTALLATION
2-Bearing housing. 3-Shaft. 4-Fixture. 5-Fixture adapter. 6-Support screw.

5. Install spacer (10), thrust ring (9), spacer (8) and thrust bearing (7).

NOTE: The bolt holes in the spacer and thrust bearing are staggered to eliminate the possibility of installing these items incorrectly.


INSTALLING THRUST BEARING
7-Thrust bearing. 8-Spacer. 9-Thrust ring. 10-Spacer.

6. Install thrust ring (12) and oil deflector (11).


INSTALLING OIL RETAINER
11-Oil deflector. 12-Thrust ring.

7. Tighten bolts (17) to torque given in the group, SPECIFICATIONS, and bend the locks which secure bolts (17).

8. Place sleeve (14) over the shaft.

NOTE: Position sleeve (14) with ring seal grooves away from the bearing housing.

9. Install ring seals (15) on sleeve (14). Position the gaps 180° apart.

10. Install seal (16).

11. Install insert (13). Position the retaining ring with the flat side toward the insert.


NOTICE

Install the insert with care to avoid damaging the ring seals.



INSTALLING INSERT
13-Insert. 14-Sleeve. 15-Ring seals. 16-Seal. 17-Bolts (three).


SPACER BLOCK

12. Place the approximate amount of shims needed on the shaft and install spacer block (19) and nut (18). Tighten the nut to the specified torque.


CHECKING IMPELLER TO HOUSING CLEARANCE
18-Nut. 19-Spacer block.

13. Thread the support screw against the turbine end of the shaft just enough to remove all end clearance. Using a thickness gauge on each side of the spacer block, check impeller to bearing housing clearance. This clearance is regulated by shims under the impeller; add or remove shims as required. See the SPECIFICATIONS for correct clearance.

14. Remove nut (18) and spacer block (19) and install the correct number of shims.

15. Carefully install impeller on the shaft.

NOTE: Make certain the support screw pushes the shaft firmly toward the impeller end during this operation. Also make certain the impeller bottoms on the shaft.

16. Install a new nut and tighten to the specified torque. See the SPECIFICATIONS.


NOTICE

Use a double universal joint to prevent bending the shaft.


17. Recheck the impeller to bearing housing clearance and the end clearance.

18. Make a final inspection to determine if any blades have been accidentally damaged or bent during the assembly operation.

19. Install the nozzle and turbine housing. The two bolts marked X have drilled heads for installation of the turbocharger seal. The four bolts marked Y are for installation of the turbocharger mounting bracket. Tighten the bolts to the torque value given in the SPECIFICATIONS and secure the bolt locks.


INSTALLING NUT

20. Install the compressor cover with a new seal and tighten the band clamp to the torque value given in the SPECIFICATIONS.

Caterpillar Information System:

D399, G399, D398, G398, D379, G379 ENGINES Turbocharger
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