Firstfives.org

I recently had my exhaust system replaced with a
bosal middle muffler and a BMW rear I managed to somehow get my hands on.


IT MAY BE SOME UNRELATED ISSUE I'M HAVING {FPR maybe}, but the car has a loud grunt and sounds like an old diesel benz when I'm idling. Sometimes, I think, it gets quieter, but I'm so far down the rabbit hole I don't know any more.

When I give gas, the exhaust quiets to a nice "vvvvvvvvvvvvvv".

My question is: is the stock system diesel-ish loud?

Does anybody else have the Bosal central muffler?
Is it loud?

Leaking exhaust gaskets can sound 'diesel-ish' maybe pop your head under the car to see if you can pinpoint a leak?

I had the same feeling about my '76 3.0Si (same engine and exhaust system pretty much as yours) with a new BMW/Bosal center and rear muffler. The idle sounds truckish to me but very smooth and quiet once under way.

I just got under it this week to change the ATF and check on the guibo alignment so I had to remove the exhaust. I'm wondering if it's a matter where each of the connection rings go and resulting leak. Where the two downpipes connect to the middle muffler, one pipe has the somewhat compressible ring (PN 18119067822) made of some gasket material (newer ones are covered in a thin metal jacket) and the other pipe connect via a solid steel thin donut/ring. My exhaust had the solid steel ring slipped over the downpipe with the removable flange, the one that has no preformed lip. And the compressible ring on the other two pipes where each pipe has a lip and the meet with a ring in between, in my case the compressible ring.

Does anyone know which style ring goes on which pipe?? I will exchange their positions when I put it back together tonight and see if it's better.

I did check for leaks-
the engine stalls if I put a rag over the exhaust, so its tight, but there is one tiny tiny tiny pin whole leak between the downpipe and central muffler.

The thing of it is, my exhaust gets quieter when I drive, and sometimes its quieter an idle than other times. Maybe the guy who installed it did something wrong. I'm starting to think however my fuel pressure regulator is giving me consistent but lower pressure, causing me to run rich because the fuel is not atomizing correctly- I guess we will find out soon.

Luis- my exhaust system was just welded all together. The muffler guys said the clamps tend to come off, I don't know if this is true or not-

In any event, there is a diagram on bosalna.com telling you what goes where but their site is down now.

Luis;
You just hi-jacked CB's post!! You can easily post with your own issues, right?

LOL

I dont mind at all!

I think theyre sufficiently related;
If one has a loud bosal exhaust in the future,
This may someday be useful, if Luis posts his results!