2003/02/01 Caterpillar

Engine:

G3412C (S/N: 6ZM1-UP)

The turbochargers on some G3412C Low Emission engines have experienced premature failure of the thrust bearing. The turbocharger thrust bearings were failing due to an abrupt shutdown of the engine while the engine was at rated load and the engine was at rated speed. The thrust bearing for the turbocharger was being starved for oil. In order to correct this failure, an accumulator has been installed to all G3412C Industrial engines. The accumulator supplies the turbocharger bearing housing with oil until the initial thrust of back pressure has ended.

The Turbocharger Oil Lines Gp that contains the accumulator can be applied to engines with the following turbochargers: 197-7496 Turbocharger Gp, 122-8043 Turbocharger Gp and 162-9471 Turbocharger Gp

The 216-7735 Turbocharger Oil Lines Gp is not available for parts service. Order the individual components for parts service.

Note: The use of 225-6998 Tube As or the use of 217-7898 Tube As depends on the type of turbocharger. Determine the part number of the turbocharger that is used on the engine prior to ordering parts.

Use the following installation instructions in order to install the accumulator for turbocharger oil lines:

Illustration 1	g00948015
Turbocharger oil lines (left side view) (1) Bolt (2) Elbow (3) Tube As (4) Strainer, or Gasket (5) Connector, and O-Ring Seal (6) Bolt, Hard Washer, and Full Nut (7) Bolt, and Hard Washer (8) Support (9) Bolt, Hard Washer, and Full Nut (10) Turbocharger Accumulator Gp (11) Clamp

Illustration 2	g00948020
Turbocharger oil lines (rear view) (12) Tube As, or Tube As (13) Bolt, Hard Washer, and Full Nut (14) Clip (15) Pipe (16) Bolt, and Hard Washer (17) Upper Bracket Assembly (18) Lower Bracket Assembly (19) Tube As (20) Elbow, and O-Ring Seal (21) Spacer

Illustration 3	g00949161
Check valve (22) Tee (23) Check Valve (24) Connector, and O-Ring Seal

Illustration 4	g00948021
Balance line (25) Tube As (26) Clip (27) Spacer (28) Bolt, and Hard Washer

1. Remove the existing oil supply tube to the turbocharger. Remove item (14) and (16) and retain item (14) and (16) for the installation of the new oil supply tube. Also retain (1) Bolts at the inlet of the turbocharger oil supply for the installation of the new oil supply tube.

2. Remove the tube for the balance line and the bracket and the clip that secures the tube. These components can be discarded.

3. Before removing bracket assemblies (17) and (18), remove the lower bolts, washers, and nuts from Upper Bracket Assembly (17) for the junction box. Hold Support (8) in place along the top of the mounting bracket for the air cleaner and against the upper bracket assembly for the junction box. Mark two additional holes on the mounting bracket for the air cleaner. Mark two additional holes on the upper bracket assembly for the junction box. Remove bracket assemblies (17) and (18) for the junction box and discard the bolts, washers, and nuts.

4. Drill two 15.88 mm (0.625 inch) holes in the mounting bracket for the air cleaner in the locations that were marked in Step 3. Drill two 11.11 mm (0.438 inch) holes in Upper Bracket Assembly (17) for the junction box in the locations that were marked in Step 3.

5. Install Support (8) for the accumulator to the top of the mounting bracket for the air cleaner. Use the hardware that is listed in item (6) in Table 3 in order to fasten the support to the top of the mounting bracket for the air cleaner.

6. Install Upper Bracket Assembly (17) and Lower Bracket Assembly (18) for the engine mounted junction box. Use the hardware that is listed in items (9) and (21) in Table 3 in order to install the bracket assemblies. Install spacers (21) behind the mounting brackets in order to properly space the mounting brackets.

7. Install the new oil supply lines and the check valve that is shown in the Illustration 1 and 2. Refer to the Illustration 3 for a detailed view of check valve (22) and the connections. Use 217-7898 Tube As (12) for an engine that is equipped with the 197-7496 Turbocharger Gp. Use 225-6998 Tube As (12) for an engine that is equipped with the 122-8043 Turbocharger Gp and the 162-9471 Turbocharger Gp. Use the following items in Table 3 that are needed to install the oil supply lines and the check valve: Strainer (4), (12), (19), (22), (23) and (24) .

8. Install Turbocharger Accumulator Gp (10) and attach the accumulator to Support (8). Use the following items in Table 3 that are needed to install the accumulator: (7), (10), (11), (13) and (15) .

9. Install the fittings at the top of the accumulator in order to make the connection to Tube As (3). Use the hardware that is listed in items (2) and (5) in Table 3 in order to make the connection.

10. Install the following items (14) and (16) that were removed in Step 1.

11. Ensure that all of the fittings and the fasteners are tight. Remove the guard and remove the valve cap from the bottom of the accumulator. Pressurize the accumulator to 310 ± 35 kPa (45 ± 5 psi) with the use of dry nitrogen gas.

12. Install Tube As (25) for the balance line. The fitting at the gas pressure regulator needs to be rotated 90 degrees in a clockwise direction in order to make the connection to the tube assembly. Use the following items in Table 3 in order to retain the tube assembly: (26), (27) and (28)

13. Start the engine and run the engine for 15 minutes. Stop the engine. Remove Strainer (4) and replace the strainer with Gasket (4) .