| Subject: | Engine Oil Leak at Intake Gasket - Possible Internal Cylinder Head Porosity |
| Models: | 2004-2006 Buick Rainier |
| 2002-2006 Chevrolet TrailBlazer |
| 2002-2004 Oldsmobile Bravada |
| with 4.2L Engine (VIN S - RPO LL8) |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
On rare occasions, an engine oil leak may be noted just below the PCV port between the number 3 and number 4 intake manifold runners. This may be due to oil that settles in the bottom of the intake manifold due to an internal porosity concern with the
cylinder head that can cause oil to enter the PCV system.
Recommendation/Instructions:
If the SI diagnostics do not isolate a cause for the above leak, inspect the engine for excessive crankcase pressure by using a manometer and check for restrictions in the PCV system. If there is no problem found, replace the cylinder head for evaluation.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
