Exhaust Leak
 

Hi All,

I have a small exhaust leak which is preventing my vehicle from passing inspection. I honestly did not think they would even notice it at low RPM. I am stumped trying to find it. The leak is definitely coming from the front and the closest that I can track it to is the passenger side. I found one thread talking about a cracked exhaust manifold. Is this common? The only two gaskets in this area are the manifold gasket and the down-pipe "donut". Has anyone ever blown a manifold gasket? How about the donut?

The vehicle is a 1998 Bravada 242K miles with original manifolds, Y-pipe and muffler. Only the cats have been replaced, so the Y-pipe has been removed from the manifolds before. I did not replace the donuts when I pulled the pipe out to replace the pre-cat.

I need to buy the part ASAP so I can show the police a recite if I get pulled over for having the "REPAIR" sticker on the car. I am REALLY hoping it is not the manifold gasket, but if it is, I will probably just get a set of headers for all the trouble that it would be to fix it.

-William

poke poke...

I don't think that cracked exhaust manifolds are prevalent on the s-series trucks, but it can happen. You pretty much need to determine exactly where it is coming from. A length of small tubing can be used by putting it up to your ear with a rag over that end and then tracing along the manifold and gasket joints with the other end. Listen for the leak.

Wow that worked really well! I found two leaks. First is the drain holes in the muffler have rusted into the muffler housing and exhaust comes right out of them. Meh...Its the original muffler. I will wrap some muffler tape around it for the test. The leak that was causing me to fail was actually pretty wild. The Y pipe cracked at the collector all the way around the weld for the pipe that goes up to the passenger side. Whenever you give it some gas under load (wheels blocked, ebrake on, friend standing on brakes and giving it gas in D), the pipe deflects 1-2mm out of the pocket in the collector and leaks big time. At idle or even reving without load the crack is almost invisible. I welded about 1/3 the way around it, where I could get at without taking the pipe out of the car. I will tape up the rest of the crack before heading back for the inspection. Thanks again for the tip! I will remember this one.

-William