Engine Oil Leak at Vacuum Pump Oil Supply Pipe (Replace Vacuum Pump Oil Supply Pipe)

Some of the above listed vehicles may exhibit an engine oil leak at the vacuum pump oil supply pipe. This condition occurs primarily on high mileage engines.

Pipe material fatigue due to engine vibration and thermal stress may cause this condition.

A new oil pipe has been developed with increased fatigue resistance to correct this condition. Replace the vacuum pump oil supply pipe on the affected vehicles. For 1999-2001 MY vehicles only, a new right side engine mount with a clearance notch is also required to install this new pipe. The 2002 MY vehicles have the updated right engine mount. Use the following procedure and the part numbers listed below.

1. Apply the parking brake.
2. Block the wheels.
3. Tilt the cab and secure the safety lock pin.
4. At the rear of the generator, remove the banjo bolt that attaches the oil supply pipe to the vacuum pump. Discard the two seal washers.
5. Remove the banjo bolt from the oil supply pipe connection at the engine block. Discard the two seal washers and the hose.

Notice: Do not place a jack under the oil pan sheet metal or crankshaft pulley. Due to the small clearance between the oil pan and the oil pump screen, jacking against the pan may cause oil starvation and engine failure. Jacking under the crankshaft pulley may distort the inertia ring and create and engine vibration.

6. Support the engine at both sides of the oil pan rail or use a lift sling assembly.
7. On each side of the engine, remove the two bolts that attach the engine mount isolator to the crossmember.
8. On the right side of the engine, remove the four bolts that attach the engine mount bracket to the engine block.
9. Slightly raise the engine and remove the right side engine mount assembly.
10. Remove the single nut and lock washer that attaches the insulator to the engine mount bracket. Discard the old engine mount bracket on 1999-2001 MY vehicles only.
11. On 1999-2001 MY vehicles only, install the new engine mount bracket to the isolator and tighten the single nut with lock washer.

Tighten
Tighten the nut to 83 N·m (61 lb ft).

12. Insert the engine mount assembly into position with the two isolator bolts.

Tighten
Tighten the two isolator bolts to 47 N·m (35 lb ft).

13. Lower the engine.

Tighten

•	Tighten the four engine mount bracket bolts to 51 N·m (38 lb ft).

•	Tighten the two left side isolator bolts to 47 N·m (35 lb ft).

14. Insert the new oil pipe through the right side engine mount bracket.
15. Using new banjo sealing washers, loosely install the new pipe on the vacuum pump and the engine block.
16. Insert the new oil pipe bracket securing the bolt through the bracket and into the engine mount.
17. Inspect the generator belt tension and condition. Adjust or replace the belt, if necessary. Ensure that the upper and lower generator bolts are properly tightened.
18. Tighten the oil pipe banjo bolt at the vacuum pump to 23 N·m (17 lb ft).
19. Tighten the oil pipe banjo bolt at the engine block to 41 N·m (30 lb ft).
20. Tighten the oil pipe bracket securing bolt at the engine mount to 51 N·m (37 lb ft). Ensure that the new oil pipe does not contact the engine mount bracket.
21. Close the cab.
22. Remove the wheel blocks.
23. Start the engine. Verify that there is no oil leaking at the banjo fittings.

For Chevrolet and GMC Models:

Parts are currently available from GMSPO.

For Isuzu Models:

Parts are to be obtained from AIPDN.

For vehicles repaired under warranty, use: