Before you start your diagnostic investigation of any driver’s complaint, make sure you are not wasting time looking for a fix that already exists. Accessing manufacturers’ repair information, including technical service bulletins (TSBs), can save you an enormous amount of time and trouble. TSBs are the first thing to check when a customer comes in the door. His or her complaint may already be recognized as a problem that developed after the vehicle left the factory.
Even a seemingly simple issue, such as a noisy exhaust system may have a documented repair procedure just waiting for you to look it up. And OEM repair information includes parts numbers to make ordering fast and easy.
Here, as an example, is an excerpt from a TSB from GM® concerning an exhaust leak and noise. The TSB has been slightly reformatted for the purpose of this Tech Tip.
Exhaust System – Exhaust Leak/Rattle/Rumble/Noise
Some customers may comment on an exhaust leak or noise. The noise may be described as a rattle or rumble. This condition may be caused by an unseated pipe to pipe mid-joint connection (Figure 1). To correct the problem, install a new clamp and align the pipe/connection correctly.
All Equipped with 6.2L Engine:
2011-2012 Cadillac Escalade, Escalade ESV®, Escalade EXT®
2011-2012 Chevrolet Avalanche, Silverado, Suburban
2011-2012 GMC Sierra, Sierra Denali®, Yukon Denali, Yukon XL, Yukon Denali XL®
Review safety procedures in ALLDATA® Repair S3000SM before beginning.
NOTE: Ensure that the pipe flares remain fully seated to each other while tightening
the clamp (Figure 2).
1. Remove and discard the exhaust band (Norma) clamp.
2. Install and position a new exhaust band (Norma) clamp to the pipe joint.
3. Firmly push and maintain the pipes together while tightening the exhaust band (Norma) clamp bolt. Tighten the clamp bolt to 28 Nm (21 lb ft).
NOTE: After the clamp is installed, it does not need to be perpendicular to the pipe. It is acceptable to have a pipe to pipe or clamp angle.
4. Confirm that the clamp edges (both sides and all the way around the clamp) are fully seated
on the pipe.
5. Run the engine and inspect the clamp joint to ensure there are no leaks and that the condition is corrected.
NOTE: This Repair/Service Procedure is excerpted from a Technical Service Bulletin published by the vehicle manufacturer, and is intended for use by trained, professional technicians with the knowledge, tools and equipment to do the job properly and safely. It is recommended that this procedure not be performed by “do-it-yourselfers.”
General Motors, Cadillac, Escalade, Escalade ESV, Escalade EXT, Chevrolet, Avalanche, Silverado, Suburban, Tahoe, GMC, Sierra, Denali and Yukon are registered trademark names and model designations of General Motors. All trademark names and model designations are being used solely for reference and application purposes.