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G/H V
an
(Section 8 — continued from previous page)
Check for leaks in exhaust systems and repair as required.
NOTE: The manifold joint take down pipe and converter assembly incorporating oxygen sensors is designed to suit OBD II requirements,
which are dependent upon specific gas leakage rates at the joints. Ideally this assembly should not be disturbed during the body
manufacturing process.
Exhaust gas temperatures can exceed 1600ºF under extreme operating conditions, with pipe surface temperatures slightly less than
this. Extreme care must be used when placing body components in the proximity of the exhaust system so as not to exceed the rated
temperature limits of the components. Due to variants in underbody configurations of the vehicles, General Motors is not in a position to
make recommendations on how to insulate or design components in the proximity of the exhaust system.
Each manufacturer must make temperature checks of critical areas and adjust his design accordingly, or provide shielding to ensure safe
operation of body components.
The same can be said for the engine compartment. Obviously there will be additional heat radiated from the engine. How much is retained
in the area will depend on how well the area is ventilated in your individual designs. Here again, temperature checks of interior areas
surrounding the engine should be made to determine if your insulation is adequate. This is the same engineering practice General Motors
has followed on our complete vehicles incorporating these exhaust systems.
Exhaust system materials are selected and tested to withstand the operating environment of the vehicle. Do not modify the exhaust
system in any way. The tail pipes are made of 409 aluminized stainless steel.
Heat shields are mounted to the chassis, underbody and/or exhaust system components (tail pipe).
2007 I Diesel Exhaust Systems, option LMM, Duramax 6.6L Diesel
• Beginning in 2007, vehicles with diesel engines have been equipped with exhaust particulate filters. The exhaust systems have been
specifically designed in conjunction with the engine hardware and software to meet the emissions certification requirements established
by the U.S. Environmental Protection Agency. For this reason, modifications to any part of the exhaust system between the engine and
exhaust particulate filter outlet are not permitted.
• During normal vehicle operation and during the exhaust particulate filter regeneration process, gas temperature inside the filter can
reach levels as high as approximately 650 degrees C, which is considerably higher than previous diesel exhaust systems. Therefore,
materials and components installed near the exhaust system and exhaust gas stream should be shielded or designed to now withstand
higher temperatures. On all LMM systems, an exhaust cooling device has been designed for the end of the tailpipe to significantly
reduce the exhaust gas exit temperature. This device is required, and is designed to draw in ambient air to cool the exhaust stream.
The exhaust and ambient air streams into the cooler assembly should remain unobstructed and free from foreign material.
G/H Van 2007 – Rev. 5-07
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