1.9Tdi A4 Avant (B5) auto - Engine vibes through body

[PaulF99]

I have just bought a friend's 1999 model A4 B5 1.9 Tdi Avant (auto) for a smallish sum. It's very high mileage (175,000 ), but everything works, there's no rattles, the bodywork is in good condition, and it drives well. It was maintained up to 120,000 by the local Audi dealer, and then by a big fleet-maintenance operation, so has been looked after. Has only been used for motorway journeys.

The only thing I could find wrong when I test-drove it, was a vibration on the over-run, most pronounced at around 2200rpm, most noticeably when cruising at 60-70mph. Same vibration is also evident when revving the engine whilst stationary. So, it seems there is some coupling of the engine to the bodywork in some way, particularly when the drive-train is driving the engine. I reckoned it could be engine mounts, exhaust mounts or routing, or similar.

I took it along to my local independent Audi specialist for them to diagnose the problem, but, having spent a half-day looking at the car, they have informed me that they are not sure what the cause is. It's not the exhaust, or any pipe-work, They feel it may well be the engine mounts, but rather than waste my money on trial and error fixes (they didn't charge me anything, which was nice), they suggested I try to find someone with some other ideas who may be able to pinpoint the exact cause, eg maybe Audi dealer with access to a database of problems and symptoms.

Anyone have any ideas? Had a suggestion that it might be the front engine mount (snubber) that has worn.


Paul

[stubbsy]

although you have been told its not the exhaust i would check again.quit a common problem on audi tdi,s.i have the same symptoms but i just turn the music up a tad what happens is with the down turned exhaust pipes on the back box these are commonly "clipped" on kerbs etc when reversing which in turn pushes the system forward and "cracks the flexible joint" just before where it bolts to the turbo.it cant be seen as the woven part hides it. the previous owner must have done this on my car,as i said, i try to ignore it but it does my head in,to fix i need a new front pipe CAT INCLUDED a friend of mine who owns a tyre and exhaust place told me this.he says its quite common.try it anyway

[PaulF99]

Stubbsy,

Thanks for the info. The car is booked in for a cambelt change next week, so I will get the guys to check for the cracked exhaust at the same time.

The front engine mount will have to be removed anyway for the cambelt change, so I should be able to at least pinpoint/eliminate these two items as possible causes.

Paul

[stubbsy]

im just thinking,my mrs has an a4tdi too .when we got it we had same sort of problem. i tracked it down to the intercooler in the passenger front wheel arch.the rubber gommets holding it in place had worked loose.maybe worth a check too.obviously its something from the engine/drive train in contact with the chassis. a bit like a water leak,trial and error

[BrendanMC]

Check the clutch on the alternator, if it knackered it vibtrated. If the belt is jumping about on the tensioner then it's a good chance the clutch is gubbed.