Smoking Cats

[AP1995V6]

Whenever the car is running everything is fine. However, when I turn it off, a minute or so later white smoke starts pouring out between my secondary cat and primary cat. I've cleaned them off with degreaser and acetone so its nothing on the surface that's burning. It's also only occuring on the passenger side. No smoke comes out of the tail pipes either. I've done a compression test, and the compression was the same across all cylinders.

The smoke smells pretty terrible. I can't really compare it to anything.

 

[HISSIN50]

How does smoke come out of the pipe? Osmosis?

Does it only happen when the AC is on? It might be steam from the AC drain (hitting the exhaust).

Good luck.

 

[go-stang5.0]

If it if further back....by the rear cats....it could be a leaky tail shaft seal. ATF smells pretty gross when burning. That was my problem. It could be yours.

 

[AP1995V6]

Yes. It comes out through osmosis.

I'm not sure. I look under my car and smoke is pouring out from under the shroud around the cats. Yet nothing comes out of the tailpipes -- since it only happens when the car isn't running.

Maybe there's still some residual gunk on them that's causing them to smoke a bit. I'll know in a couple days I guess. I'm pretty terrified about my car catching on fire.

I'll have a look at the tail shaft seal.

 

[Fopar]

?

 

[HISSIN50]

Yes. It comes out through osmosis.

I'm not sure. I look under my car and smoke is pouring out from under the shroud around the cats. Yet nothing comes out of the tailpipes -- since it only happens when the car isn't running.

Maybe there's still some residual gunk on them that's causing them to smoke a bit. I'll know in a couple days I guess. I'm pretty terrified about my car catching on fire.

I'll have a look at the tail shaft seal.

I was only trying to see if you might actually have a hole in your cat housing.

You're very wise to be concerned with a fire issue. I've melted a cat down before and it sucked (the spot welds broke loose, which allowed the matrix to get cockeyed, thus blocking exhaust flow).

There are backpressure gauges but most of us don't have them. One can infer a little from watching manifold vac. Hold the throttle uber steady at 2500-3K RPM (in that range - but once you pick a value, keep it steady). Watch the vac gauge for a minute or so. An exhaust restriction will show manifold vac dropping even though you are not changing throttle position.

I like the go-stang's external crap on the cat housing idea. It's weird that it's only picking on one side though. double check for leaks on that side of the engine/trans too.

Fopar - I was waiting for that.

Good luck.