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

Operation

TURBOCHARGER SECTION

1 Thrust ring.

2 Thrust bearing.

3 Compressor cover.

4 Thrust ring.

5 Spacer.

6 Clamps.

7 Shaft.

8 Nozzle.

9 Turbine back plate.

10 Lock rings (three).

11 Sleeve.

12 Turbine housing.

13 Shims.

14 Nut.

15 Compressor impeller.

16 Turbine wheel.

17 Ring seals (two).

18 Ring seals (two).

19 Spacer.

20 Retaining ring.

21 Seal.

22 Insert.

23 Oil deflector.

24 Bearing housing.

25 Vent tube.

26 Oil drain hole.

27 Bearings (two).

28 Sleeve.

29 Oil slinger.

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 (25) vents the oil cavity to the crankcase. Venting this cavity promotes draining of oil from the 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 (27). Filtered engine oil is supplied through passages in the housing to lubricate the shaft bearings (27) and thrust bearing (2). This oil aids in removal of excessive heat. Oil returns from the turbocharger to the crankcase through an external tube at (26). Thrust loads are absorbed by stationary thrust bearing (2) and rotating thrust rings (1) and (4). Oil deflector (23) routes the oil, thrown from the shaft and thrust rings, back to drain opening (26).

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 (if so equipped). 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 assembly, impresses the letters DLR on the seals.

TURBOCHARGER FACTORY SEAL
1-Seal.

Checking Bearing Clearances

A quick check of bearing condition can be made without completely 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 at A or the turbine wheel rubbing the turbine housing at B, 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 SPECIFICATIONS for these diameters.

CHECKING FOR BEARING WEAR
A and B-Locations to check for scuffing.

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

Checking Turbocharger Shaft End Clearance

See the 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.

CHECKING SHAFT END CLEARANCE

Disassembling The Turbocharger

Compressor Cover and Turbine Housing

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

Prior to disassembly, mark compressor cover (1), turbine housing (4) 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-Clamps. 4-Turbine housing.

REMOVING NOZZLE
2-Bearing housing. 5-Turbine back plate. 6-Nozzle.

Rotating Parts

Before disassembling 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 bearings 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 (3) to fixture (5). Place bearing housing (1) on the fixture adapter, with the turbine wheel down, and secure the housing flange to the adapter with clamp bars (2).

REMOVING IMPELLER RETAINING NUT
1-Bearing housing. 2-Clamp bars (two). 3-Adapter. 4-Fabricated bar wrench. 5-Fabricated fixture. 6-Supporting screw.

2. For best results, mount the fixture to a work bench so both hands can be used to loosen the retaining nut.

WRENCH

3. Install the fabricated bar wrench into the turbine wheel and support it with screw (6).

4. Using a T-bar drive and socket, remove the retaining nut. Use uniform pressure on each side of the drive to prevent bending of the shaft assembly.

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

5. Remove the fixture from the bench and loosen supporting screw (6) so the shaft can be pressed downward. Leave a space between the end of the screw and the turbine wheel equal to, or slightly greater than the impeller thickness. This will prevent the turbine wheel and shaft from being damaged as the shaft is being pressed out of the impeller wheel.

6. Use a press and a dowel (or pin) slightly longer than the impeller thickness to press the shaft through the impeller.

7. Remove impeller (7) and shims (8).

8. Remove the turbine wheel and shaft.

REMOVING TURBOCHARGER IMPELLER
7-Impeller. 8-Shims (as required).

9. Measure the shaft journal diameters and inspect the journals for roughness. If the journal diameters are less than specified, replace the shaft and turbine assembly. See the SPECIFICATIONS for correct dimensions.

10. Inspect the ring seals and measure their thickness. Measure the width of the ring seal grooves. See the 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 bearing 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 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), the wear washer and bearings (15) and (17). See the SPECIFICATIONS.

MEASURING THRUST BEARING THICKNESS

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.

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.

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

NOTE: Earlier bearings (3) were interchangeable. Later (and parts service for earlier) are not. Install the bearing without the groove nearest the turbine.

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

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

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. Place bearing housing (2) and shaft (3) as a unit on top of fixture adapter (5) using support screw (6) to hold the shaft in place. Clamp bearing housing (2) flange to the fixture adapter, making sure there is some play between the support screw and the end of the shaft.

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).

7. Tighten bolts (17) to torque value given in the 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.

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

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

10. Install seal (16) and lubricate with a small amount of oil.

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

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 equal dimension thickness gauges on opposite sides of the spacer block at the same time 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.

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.

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

15. Carefully install impeller on the shaft.

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

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

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

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

20. Install the turbocharger nozzle. Align the mark (made prior to disassembly) on the turbine housing with the corresponding mark on the bearing housing and tighten the band clamp to the torque value given in the SPECIFICATIONS.

INSTALLING NUT

21. Install the compressor cover, position the alignment marks and tighten the band clamp to the torque value given in the SPECIFICATIONS.

22. Turn the impeller by hand to be certain there is no rubbing or binding within the turbocharger and install the band clamp seal.

LUBRICATING TURBOCHARGER BEARINGS