1991 318is exhaust repair assistance

[Boris3]

Posted this on R3V but figured try here as well.

The car has what looks like the original cat and a newish oem catback and the oem connector 2-3" clamp and sleeve. PO installed it four years ago but only put 500-1000 miles on it so the car sat for a while.

I can see exhaust leaking from both ends of the clamp/sleeve. Tightened it down but still leaks. Any suggestions? Car is far from pristine so effective matters more than pretty.

[m42b32]

You mean #15 on the diagram?

 

When we install exhausts on the cars at the shop I work at, we use an exhaust sealant on the connections. Those old GM exhausts came in like a million pieces with these short slip joints you put clamps over, leaks everywhere guaranteed unless you use a sealant. I can't remember who makes it, I don't think what we use is anything special so its probably Permatex or something, but it works very well and would probably work in your case as well. 
 

[Boris3]

Yes #15. Thanks for posting the diagram. I've looked at that a lot and never realized until now that my car is different. I have a solid pipe from the resonater to the muffler. The #15 clamp and sleeve is between the cat and the resonator. It looks like the PO cut the flange off the cat and off the newer cat back and used the #15 clamp to hold the pipes together??

[m42b32]

I believe my car (1991 318is) is as you describe as well, the solid pipe from the connection after the cat through the muffler so there must be a bit of a discrepancy between the cars and the diagram, I believe mine is held together with a flange between the cat and resonator however (I might climb under it tomorrow because now I'm curious) so it is entirely possible that what you said is what happened with yours? I'm no expert mechanic by any means but I would guess some exhaust sealant would work pretty well at sealing it up

[Boris3]

I think the old part was a solid piece. I checked a few suppliers and all that is available now us the two piece version.

I'll give the sealant a try. I think

I have a tube of permatex muffler / tailpipe sealer somewhere.

[merl]

Rich .. try one of these from Napa. I used them on the e28 and they worked great. I also have parts for you at my shop.

 

[Boris3]

Thanks. Thought I might have to get some exhaust welding done so I decided to head to my local Wisconsin Muffler this morning. Sitting here now. PO did cut the flanges off the cat and the catback leaving more than an inch gap and used the clamp and sleeve to try to hold it all together. Solution will be custom cut a connector pipe and clamp or if that doesn't work weld.

Parts, wow I figured that this was still on the back burner. I'm meeting crowntheking this afternoon for a red door and fender if his part out goes through.

[Boris3]

Solution: custom connector pipe welded to catback and clamped to the cat so I don't have to replace the whole exhaust if one part goes bad. Much quieter!