Ive got an exhaust leak on my truck and cant seem to figure out where from. The motor and cats were replaced recently. The noise is most noticible when starting the truck with the window open. I would think it would be the exhaust manifold as that should have just been bolted down tight with a new gasket. Plus it doesnt sound like a manifold leak, its not really audible in the cab like manifold leak ive heard. So whats the easiest way to determine the leaks source?

Thanks in advance for any help, i hate an exhaust leak. Makes me feel like im driving a old beater truck

 

Look for black marks.

 

Start the truck cold, and feel around all the seams. You will feel a leak. Black marks will also show.

 

Yup, black soot marks and with the truck running, have someone place a thick rag/towel over the tailpipe restricting the flow...the sound will pop out (so to speak)

 

Check the bolts on the manifold again. For headers at least, you snug them up after install, drive i little bit and get everything seated, then tighten them down to spec.

 

Hold a piece of pvc pipe or hose up to your ear and move the other end around where you suspect the leak may be.

 

Hook up a shop vac or blower to your exhaust pipe and turn it on. The engine is off. Spray a soapy water around every possible leak point. That's how I found my manifold gasket leaking.

 

Smart guy

That's what works best. I use compressed air myself @ about 15-20 lbs, - only because I have the fitting reducer for the tailpipe. I know those Rigid shop vacs will plug right tho lol.

Yep, soapy water on the seams reveals all.

 

I'm suspecting a small exhaust leak, because after driving a while with blower on Low I'm getting a headache. With blower on High it doesn't bother me. My passenger side manifold has bolts into the head instead of studs and nuts, so it appears someone had some problems with it at some point. I can't hear any obvious puffing. I tried feeling around the manifold with the truck running, and I think I can feel a small leak, but it's hard to tell with all the air flow in that area with the fan running. I tried testing the air for CO with a battery powered home CO monitor, but it didn't show any reading above zero, so apparently it isn't really bad.

jbrew - Where did you get the fitting to connect the compressed air to the tailpipe? This seems like a good way to get the exhaust system pressurized. Also, I have a dual exhaust - any good way to plug the other side? I was thinking of using a big sponge with a plastic bag wrapped around it.