| Subject: | Leak From Transmission Oil Cooler Line Fitting on Vehicles Built in April or May, 2008 |
| Models: | 2008 Chevrolet Avalanche, Colorado, Express, Silverado, Suburban, Tahoe |
| 2008 GMC Canyon, Savana, Sierra, Yukon, Yukon XL |
| Equipped with 4L60E or 4L70E (RPO M30 or M70) Automatic Transmission |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
Some customers may comment on a leak from the transmission. Further inspection may find that the leak is coming from a transmission oil cooler line quick connect fitting at the transmission. The vehicle involved would be have been built in April or May,
2008.
Recommendation/Instructions:
This leak condition may be caused by an incorrectly machined transmission oil cooler line quick connect fitting. Remove the transmission cooler lines from the quick connect fittings and inspect the inner diameter of the fitting. In a correctly machined
fitting the O-ring is almost fully recessed in the groove (figure 1). In an incorrectly machined fitting the O-ring is exposed (figure 2). If the leak is determined to be caused by an incorrectly machined cooler fitting or cut O-ring seal it should be replaced
with parts obtained from GMSPO.
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.
