I discovered broken/missing exhaust manifold bolts at 107K miles although I suspect they have been missing for quite some time. I was made aware of the problem by other Cadillac, Chevy, and GMC owners with the 6.0L engine. Upon hearing about this issue I inspected my vehicle to find that I have missing/broken exhaust manifold bolts too. This is a major safety concern as well as emissions. Many owners of these vehicles with this engine have had multiple missing or broken manifold bolts, many at mileages of less than 50K. Exhaust temperatures at the exhaust manifold average 1200 degrees Fahrenheit. Gasoline has an ignition temperature of about 500 degrees Fahrenheit. When exhaust manifold bolts break or become missing the seal is compromised between the exhaust manifold and the exhaust port on the engine cylinder head allowing these extremely hot exhaust gases to come into contact with multiple components in the engine compartment rather than through the exhaust system and safely out the tailpipe, which is routed safely away from flammable components or components that could compromise vehicle handling or braking if exposed to these temperatures from normal operation. Heat shields as part of the exhaust system are installed to safely shield any of these components from the exhaust system temperatures as long as the exhaust system is in good working condition. In addition there are other fluids such as transmission fluid, power steering fluid, engine oil, that will also burn if exposed to these normal exhaust manifold temperatures. All of these fluids, including fuel lines, flow through lines in and around these manifolds routed throughout the engine compartment. Should the entire exhaust manifold become loose because of the insufficient mounting hardware the risk of fire become exponentially higher. There are other concerns such as carbon monoxide and excess polluti.

- Shelby Township, MI, USA