Upper Engine - Oil Leaks

Group: 15

Number: 94-02

Date: Aug. 1, 1994

Subject:
Engine Oil Leaks, Upper

Model(s):
90, 100, Engine Code AAH (V6 Engine) All m.y.

Condition

Accumulation of oil in the V6 engine intake valley because of:

^ Leaking cylinder head gaskets

^ Leaking valley pan gasket

Caution!
0il leaks from the intake valley can be mis-diagnosed as a rear crankshaft oil-seal leak. Also see Technical Bulletin 94-04, Repair Group 17.

Production

Modified cylinder head gaskets:

Part Number: 078 103 383 E
VIN Number: 4APN100660
8GPA007244

Valley pan gasket:

Part Number: 078 103 771

Caution!
Part numbers are for reference only Always check with the parts department for the latest in formation.

Service

- Use a small flashlight to inspect the intake valley area to determine if the oil leak is coming from the valley pan cover or the head gaskets.

Leaking head gaskets, checking

- Check the turning torque (cold) on the cylinder head bolts (in the tightening direction) by using a beam or dial type torque wrench.

If it requires less than 40 Nm (30 ft lb) to turn any one head bolt:

- Loosen and retorque each bolt one at a time using the following procedure.

Cylinder head bolt torquing procedure

Cylinder Head Bolt Torque Sequence:

- Tighten the bolts to 60 Nm (44 ft lb) in the sequence as shown in the illustration.

- Turn each bolt an additional half turn (180°). It is acceptable to achieve the additional movement in two 90° increments.

Caution!
It is not necessary to re-tighten the cylinder head bolts after repairs or as part of the inspection service.

- Clean all traces of oil leakage from the engine and test drive the vehicle to see if torquing has corrected the oil leakage.

If the oil leak has stopped after torquing

- Return the vehicle to the customer.

If the oil leak continues after torquing

- Replace both cylinder head gaskets.

Leaking valley pan cover, checking

Engine Valley Pan:

- Remove the intake manifold to gain access to the valley pan cover, see Repair Group 15 for additional information.

- Remove the valley pan cover and gasket.

- Inspect the cover for distortion or warping. If the cover is warped

- Sand the cover until flat (on a flat surface) and verify flatness with a straight edge reference.

Oil Non-return Valves:

- Inspect the oil non-return valves (arrows) while the valley pan cover is off to ensure they are tight, if loose, re-install in the engine block using a suitable thread locking compound.

- Clean the valley pan contact surface area thoroughly and install a new gasket.

- Clean the intake valley and adjacent areas to allow visual verification after re-assembly that the oil leaks have been fixed

- Re-assemble the intake manifold and run engine to ensure there are no intake leaks.

- Road test the vehicle for 10 miles minimum. Re-inspect the valley area and engine bottom to ensure that all leaks have been corrected.