Full Size Utilities With Misfire Coolant Loss Or Running Rough - keywords 07 5.3L cool cooling combustion DTC head leak LMG LY5 LC9 miss odor over overheat porosity P0300 SES smoke white
| Subject: | Full Size Utilities With Misfire, Coolant Loss, or Rough Running |
| Models: | 2007 Chevrolet Avalanche, Suburban, Tahoe |
| 2007 GMC Yukon |
| Equipped with the LMG LY5 or LC9 5.3L engine |
This PI was superseded to update Recommendation/Instructions. Please discard PIP3908.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
A dealer may encounter a customer concern of misfire, loss of coolant, rough running, and/or white smoke from the tailpipe.
Recommendation/Instructions:
If a concern of rough running, misfire, or a loss of coolant has been verified, add coolant dye and complete the SI diagnosis for Loss of Coolant or Cooling System Leak Testing. In rare instances a pin hole porosity leak may be found in cylinder numbers 1, 2, 7, or 8. The pin hole is typically located in the combustion area of the head, so any coolant leaked is expected to be consumed in the combustion process.
Check the engine oil for any sign of coolant contamination. If there is no coolant in the engine oil, and a porous cylinder head has been found, replace only the effected cylinder head.
Complete the SI repair procedures for cylinder head replacement.
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.
