Exhaust sealant

[idickers]

I've got a leak in the flanged connector that joins the the catalytic converter to the rear muffler on my '91 318is. There is no gasket between the two sections, just flanges on each side that are bolted together (far left in the pic of rear muffler).


is there a sealant I could use between the two halves that might help stop the leak?
Thanks in advance for any suggestions,

[EyExR]

I doubt it. I would have a muffler shop take a look and give you some suggestions. Maybe it's a quick weld job?

Por-15 makes exhaust sealant but it never worked for me...

[idickers]

I don't want to weld it, because it is the connection between the cat section and the rear muffler section. Each exhaust section ends in a flair with a big 2-hole flange that slides up the flair to meet the flange on the other section. The two pieces of exhaust are brought together, and clamped by 2 spring-loaded bolts that hold two flanges together. But I'm leaking exhaust gas out of the joint. It's driving me nuts.

[Gary Horneck]

Its supposed to have a - Exhaust Seal Ring - in between the flanges. This one - http://www.bimmerpartswholesale.com/...580+11921+5573

[cabriodster87]

like a donut

[idickers]

D'Oh! That makes sense. It didn't come on my car, which explains a lot of the exhaust noise.
Much thanks!

[Gary Horneck]

A lot of movement right there, hence the bolt with spring. Wears the seal ring down to nothing eventually, then it just drops out. Cheap fix.

[idickers]

Hmm. Seems I spoke too quickly; there are not two flares, but one flare that connects to a rolled edge in the other exhaust, so there's no room for a donut.

So I'm back to wondering why the junction leaks when it's bolted up tight.

[Swanny]

A donut should go in there. It get crushed when you tighten things up...thus a seal is born

[Gary Horneck]

A donut like the one I linked to.

[idickers]

Except I can't find the part in realoem or Pelican.

[EyExR]

Hmm, that's strange. Maybe ask a BMW dealership. If you don't have one local, give Mitchell a call at bmwmercedesparts.com - just ask for the BMW parts dept.

Also, take a look at 18111245960 - not sure if this will fit though...

[Gary Horneck]

What about this one - http://www.bimmerpartswholesale.com/...580+11921+5573 - I bet they would sell you theirs...

[vpilarrt]

None of the several catbacks I've had on my '91 318is had a seal ring at that joint and didn't leak. Check if any of the flanges are deformed or bent and try to straighten it if it is. Might have to use some exhaust sealant (putty).

[AndrewBird]

I would try cleaning the two surfaces up. Any rust or chunks of debris could cause a leak. Hit it with a wire wheel and see if that helps.

They make this stuff, but I'm not sure how well it actually works. Might be worth a try though.

http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_muffler-&-tailpipe-sealer-permatex_7020007-p