A3 T Quattro: problem with exhaust or transmission rattle
Greetings from Scotland!
My 1999 A3 TQ has done 64000 miles and has developed 3 problems which (I hope!) may be related:
(1). A heavy metallic rattle/clunk from somewhere underneath, heard when bouncing over bumps or potholes at low speed. I hear this more when the car rocks from side to side (e.g. potpole rather than speed bump).
(2). A droning/resonance at 2900-3000 rpm (in all gears, whether accellerating or decellerating, but not when revving in neutral)
(3). After the car has warmed up, I also a low pitch vibration and heavy rattle/clunk which seems to be coming from the transmission tunnel. This is noticeable when pulling away at low speed, especially at around 2000 rpm. I think I can feel vibration/knocking coming from transmission tunnel when I put my hand over it! It goes away as I speed up speed.
The clunk over bumps (1) is much worse when (3) happens.
I have recently had the engine mount bushes replaced. A mechanic has had a look underneath and the suspension, engine mounts, exhaust mounts and anti-roll bars all seem OK.
My current favoured explanation is the exhaust clattering against the central transmission under torque, due to soft or broken mountings.
Other explanations I have considered (based on what I have read on these forums) are:
worn throwout bearing
broken catalytic conveter
break between exhaust downpipe and catalytic converter.
It is driving me crazy! Any suggestions would be very welcome!
Re: A3 T Quattro: problem with exhaust or transmission rattle
1 might be ARB bushes if coming from the front (never had it myself tho), or rear trailing arm bushes if at the rear (had that on Mk4 Golf)
2... I sort of have quiet high-pitched transmission noise in 4th, 5th and 6th. Not sure that it is. Would take it to Audi, but they'd doubtless charge an inspection fee and "not be able to hear it, sir". It happens under accel and decel, but is worst in 4th and much less audible in 5th and 6th...