buzzing

[dern]

I'm getting a metallic buzzing noise from my s3 at 2 points in the rev range, about 3500rpm and 5500rpm. It really sounds like the exhaust buzzing and I'm guessing that there's some baffles in it coming loose. It started doing it (thinking about it as I type) when I smacked the exhaust box into a sleeping policeman and had to get the front seam welded. The engine itself is very quiet (reving it to these points doesn't produce a buzz in the engine area, it comes from under the car) and the gearbox is just reconditioned. The buzzing has been going on for a year both before and after me taking the engine and gearbox out and putting them back in. It does it on the move and isn't dependant on the gear I'm in and only does it when the car is cool or very warm, I can get it to do it at a standstill but it doesn't do to such a degree (stresses on the exhaust?). There's no play on the prop so I don't think it's that vibrating.

Any one else had this, sounds like the exhaust, right?

How much am looking at for a new stainless exhaust (non-sports... it's loud enough already)? - part only, I'll fit it myself.

Thanks,

Mark

PS. Anyone got a 2nd hand one after moving to a sports exhaust. 2nd hand stainless manifolds would be an unexpected bonus

[Psychobert]

Sounds like exhaust to me, especially given what you said about smacking it.. Only thing that I'm wondering about it that I'd expect the noise to be constant once its started. So I think it would go from 3500 right up..

If there is no play on the propshaft, then with a bit of luck you won't have to do what I've just done, (see my vibrating rear end thread..).

Any difference when the engine is under heavy load or when coasting?

[HarryW]

Worth checking that the exhaust clears the chassis completely, mine was about one fag paper away in the mid section, I got it moved by no more than 2mm to stop a buzzing noise like the one you're describing. Have look you never know.

Harry

[rubyV8S]

Just had a stainless system fitted at Topcats. £275.00 + VAT for the V8, sounds gorgeous and looks the bizz.
It was recommended that the 'Y' piece was replaced with a stainless one at the same time, £60 + VAT (I'm having the stainless manifolds fitted soon) otherwise you can get rapid corrossion at the joint between the system and Y piece.

Mark

[dern]

Only thing that I'm wondering about it that I'd expect the noise to be constant once its started. So I think it would go from 3500 right up..

I think that the rpm must coincide with the reasonant frequency of whatever is buzzing, which is why I think it must be the exhaust.

Any difference when the engine is under heavy load or when coasting?

Coasting? What's that?

No, no buzzing when off the power.

Regards,

Mark

[RichardR]

I was getting some resonance between about 2500 and 3000 rpm which I thought was probably down to the exhaust against the chassis.

I checked the main supporting strap under the middle box and that seemed tight already, but I was able to tighten the rear bolt between the pipes. After doing this the resonance was gone.