Exhaust smell in cab...

[gunnjb]

My 2006 Tahoe, 5.3 liter now has exhaust smell in the cab while idling or backing up. It didn't used to at all. If i turn the A/C to recirculate the smell goes away. Don't smell it when driving. I have looked for an exhaust leak, nothing noticeable. No noise or hissing either. Any chance something under the hood could be causing this or just a leak in the exhaust system somewhere? Is the dealer the best place to get it looked at? Thanks for your help.

 

[OR VietVet]

Welcome to the forum from Oregon. May have the famous broken exhaust manifold stud on either side of the engine. Look at the exhaust manifolds and check all the manifold studs to see if any are missing. An easy way to check for a leak is to got several shop towels or any type of towels and while the engine is idling you can cover the end of the tailpipe with the rags and create backpressure. You will only be able to hold the towels there for 3-5 seconds. The pressure will build up and push your hand away. Have someone, or yourself, listen for exhaust escaping where the leak would be. Either at the manifolds or somewhere along the pipes. Usually it will be a connection area where clamped together or there is a gasket at that junction.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

You are already receiving suggestions, and other folks will chime in.

 

[gunnjb]

Welcome to the forum from Oregon. May have the famous broken exhaust manifold stud on either side of the engine. Look at the exhaust manifolds and check all the manifold studs to see if any are missing. An easy way to check for a leak is to got several shop towels or any type of towels and while the engine is idling you can cover the end of the tailpipe with the rags and create backpressure. You will only be able to hold the towels there for 3-5 seconds. The pressure will build up and push your hand away. Have someone, or yourself, listen for exhaust escaping where the leak would be. Either at the manifolds or somewhere along the pipes. Usually it will be a connection area where clamped together or there is a gasket at that junction.

Thanks for the reply. I did have several manifold studs broken off but had them all replaced and new gaskets a year ago. But I will look again to see. I did use some leak detector fluid around the exhaust manifold on a cold start and did not see any leaks whatsoever.

 

[OR VietVet]

There are other gaskets at flanges, if the system has them but yes, check the manifold gaskets too.