Right hand drive exhaust noises on the M30 E34

[myles]

I've always had a slight exhaust vibration on my car. It was rpm and load related.
I had a whole new exhaust fitted and the vibration improved and moved from 2000rpm to 1800rpm. After I took the exhaust system off to do some driveshaft maintenance the vibration got a lot worse and I had a big exhaust leak from around the flange on the manifold. The RHD cars have a different front manifold to the LHD cars. The leftys have two manifolds identical to the rightys' rear manifold, complete cast iron. The front one on a righty is part cast iron, then a stainless extension and then the flange; all to make it past the steering box. The stainless extenstion on my old manifold had a concertina style compensator in it and it had cracked on the engine side of the compensator; the source of the leak.
The compensator was the source of the ongoing vibration. The replacement manifold that I got from the wrecker/breaker had no compensator in it. It was a perfect bolt on fit and my unwanted noises and vibrations have totally gone. I can see how the compensator design will, with age, vibrate and I can make it rattle just by tapping it in the right spot.
I know that the new manifold came from an E34 535i but I don't know if it is newer or older than mine, so I don't know when production changed on this part.
Hopefully this is helpful for anyone else chasing down a similar problem.

[Paul in NZ]

i will have a look at mine next time i do an oil service,mine was produced 12 /89

[genphreak]

Mine is a 10/88 build and I had the same experience, except my flexible joint was ripped off by a conscientious exhaust fitter. It took me 2 weeks and I found a set of manifolds as you had, (minus the flexible joint). I don't know if the non-flexible manifolds came form the later cars but perhaps they do, or perhaps they are what is used on the e32 M30 powered 730i/735i.

I still have to find a new set of springs to keep the pressure up on the engine pipe joints... it'll be nice to kill the leak. Nick