| Subject: | Oil Leak At Rear Of Engine |
| Models: | 2007 Buick Rainier |
| 2007-2008 Cadillac Escalade |
| 2007-2008 Chevrolet Avalanche, Express, Silverado, Suburban, Tahoe, Trail Blazer |
| 2007-2008 GMC Envoy, Savana, Sierra, Yukon |
| with 4.8, 5.3, or 6.0L Gen IV V8 Engine |
| (RPO codes L76, LC9, LFA, LH6, LH8, LMF, LMG, LY2, LY6) |
This PI was superceded to include 2007-2008 6.0L engines. Please discard PIP4321B.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may complain of an oil leak. Upon inspection, the leak will be isolated to the rear of the engine, and could be mistaken for a rear main seal leak. In some instances, previous repairs (such as rear main seal replacement) may have been
performed without resolving the leak, This may be the result of a porous crankshaft pilot bore.
Recommendation/Instructions:
If this concern is encountered, inspect the inside of the crankshaft pilot bore for signs of oil as shown below. If present, replace the crankshaft by following SI procedures and re-evaluate the concern.
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.
