2003 Silverado 1500 HD Exhaust Fumes

I have a problem with exhaust fumes in my 2003 Silverado truck. Initially, 3 head bolts on the manifold were found to be popped off. After replacing the bolts, the exhaust fumes in the cab still existed. The truck has been evaluated by a Cherolet dealership and 2 independent garages who found no system exhaust leaks. Obviously, I am very frustrated and not sure what to do next or where to go. Any help in diagnosing this issue is greatly appreciated.

You can also get something that seems like exhaust fumes from fluid leaks ending up on the exhaust. Valve cover gaskets are a likely culprit. It wouldn’t need to be a large leak at all. Just enough so that any bit oil ends up in contact with any part of the exhaust system.

My guess is that the 2 garages & dealership have just not chased the issue very much. These places make money largely by selling and installing parts. Long periods of time spent trying to track down problems is often avoided.