Best way to chase down an exhaust leak?

[iamwiz82]

I cannot seem to find an exhaust leak that is getting louder and louder. I have tried to keep the engine running while I feel around for escaping gases, but I can only do that for a minute or two before it gets too hot to go poking blindly around the manifold and downpipe. What are some other good ways to look for them?

 

[CrackRabbit]

Could one of the local parts shops loan you a sniffer/leak detector?
I don't know if that would be one of the items they have available for loan though.

 

[drnickriviera]

Small mirror, look for black soot.

 

[lightpants]

We have a smoke machine that we use to track down evap leaks and exhaust leaks.
amazon link

The work great. I imagine that you wouldn't want to spend that kind of money to find the leak though. See if a shop near you has one, and pay them to find it for you. The nice thing is, you can do it when the exhaust system is cold. You can avoid being burnt.

 

[Rogeee]

The cheap and easy way is to grab a peice of 1/2" or 5/8" heater hose, put one end to your ear and use the other to probe around the exhaust system.

 

[nakedfrog]

Throw in some Seafoam and see where the smoke comes out?

 

[steppinthrax]

Your probably not looking good enought or you don't know enough about the system to know where exhaust could possibly leak. The exahust system is pretty simply system. It's more/less a pipe that runs from the engine out the back of the car. However, there are relativeley weak points in the system where exahust can leak. I imagine you have a single exahust in which case you have an exahust manifold that runs to a downpipe from there is a flex pipe then there is a catalytic converter the resonator and finally muffler. You first want to look at the manifold to see if it's cracked. It could be cracked from behind. You need to take off the heat sheild on the maifold. Then check the joints where the downpipe joins into the manifold. Finally the flex pipe is where most of your leaks occor. Normally that flex pipe rust out and it leaks though the wire mesh. Finally the Converter can leak and the two joints for it.

If you want to make it easier for yourself spray some carb cleaner into the intake or pcv system and start your engine. You want to get a thick white smoke. Once you get that you should easily be able to tell.

 

[Scarpozzi]

If it's not a failing weld somewhere, check to see if you have a flex-pipe. It's on a lot of imports...basically has a braided section of pipe. These sometimes split...I had one go on me a few years ago.

Steppinthrax said it. He's pretty much covered the bases.

 

[iamwiz82]

I have no flex pipe.

The problem is that you cannot see the exhaust manifold without a good amount of labor, and you cannot access the downpipe/manifold maing area without being double jointed, and you cannot see any of the rest of the downpipe because a heat shield is welded to it.

I suspect the downpipe/manifold area is the issue, but I put in a new gasket plus permatexed the entire thing. I want to get a good idea as to where the leak is before I start tearing everything apart.

 

[steppinthrax]

Originally posted by: iamwiz82
I have no flex pipe.

The problem is that you cannot see the exhaust manifold without a good amount of labor, and you cannot access the downpipe/manifold maing area without being double jointed, and you cannot see any of the rest of the downpipe because a heat shield is welded to it.

I suspect the downpipe/manifold area is the issue, but I put in a new gasket plus permatexed the entire thing. I want to get a good idea as to where the leak is before I start tearing everything apart.

This is an American Car Right?

 

[iamwiz82]

Originally posted by: steppinthrax

Originally posted by: iamwiz82
I have no flex pipe.

The problem is that you cannot see the exhaust manifold without a good amount of labor, and you cannot access the downpipe/manifold maing area without being double jointed, and you cannot see any of the rest of the downpipe because a heat shield is welded to it.

I suspect the downpipe/manifold area is the issue, but I put in a new gasket plus permatexed the entire thing. I want to get a good idea as to where the leak is before I start tearing everything apart.

This is an American Car Right?

No, Miata.

 

[Eli]

Unless you've just plain ole got a hole in one of your pipes, it's almost certainly a failed gasket... there should only be a few of them present in the entire exhaust system?

 

[iamwiz82]

Originally posted by: Eli
Unless you've just plain ole got a hole in one of your pipes, it's almost certainly a failed gasket... there should only be a few of them present in the entire exhaust system?

Well, I could be a hole or crack too. I replaced everything to the cat, including the gaskets. I also had an O2 bung welded in, so it could be leaking out of the weld there, too. I should just shove permatex in every single mating area with a thin knife or something

 

[Gew]

Eric The Car Guy suggested blocking the pipe with a rag (

) but I'm afraid by doing so I could hurt my engine.

What do you guys think?

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