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
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
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
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