| Subject: | Whistle Noise from Exhaust at 4000-4500 RPMs |
| Models: | 2006 Buick Rainier |
| 2006 Chevrolet Trailblazer |
| Equipped with the 5.3L Engine (RPO - LH6) |
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
Condition/Concern:
A whistle noise may be noted from the exhaust on moderate to heavy acceleration at around the 4000 - 4500 RPM range. This will only be noticed on some short wheel base Buick Rainier, Chevrolet Trailblazer and GMC Envoy Denali equipped with the 5.3L LH6
V8 engine. This will only affect exhaust systems that were manufactured by the supplier prior to 7/4/05.
Recommendation/Instructions:
Inspect the mufflers build date. The build dates are etched on the exhaust assembly behind the muffler just above the hanger rod on the right side of the vehicle. It can be viewed with out lifting the vehicle through the wheel well area in
front of the right rear tire. It is in the format of YYMMDD followed by the time of day and shift (A or B). Parts built before "050704" may be replaced if customer complains about a whistle. Replace the muffler with current SPO stock.
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.
