Audi A4 B7 - Audi A4 2.5 V6 tdi vibration on idle.

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Mon 22 Jul 2013 22:24
Audi A4 B7 - Audi A4 2.5 V6 tdi vibration on idle. - Hildo1
Hi My v6 2005 a4 2.5tdi is vibrating on idle and it's really frustrating . I took it to an audi dealer and they plugged it in and said there wasn't a fault but something wasn't right but could take 5 hours to find at £125 an hour so thought I'd try getting some help on here to tell my local garage what to do? It sound like its missing but I don't know that much about cars? Hope someone can shed some light as is really frustrating having a lovely car but starts vibrates like a bag of spanners when I stand still, I don't think it's serious as I have checked all the usuall things like clutch and EGR Valve, any ideas would be much appreciated Thanks in advance.
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Mon 22 Jul 2013 22:47
Audi A4 B7 - Audi A4 2.5 V6 tdi vibration on idle. - brum

Check if these are one of the VAG diesels that have alternators fitted with a one way freewheeling clutched pulley. If it has, then check that the clutch hasnt seized (common fault on other models) - easy to check with aux belt off, the alternator pulley should drive the rotor in one direction but freewheel in the other. When the clutch fails (seizes) the mass of the alternator rotor stresses the belt/tensioner which cant cope at idle speed when belt speed is not constant. Its possible to change the clutched pulley (about £50 for the part IIRC), but often people just change the alternator as its easier.

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Mon 22 Jul 2013 22:59
Audi A4 B7 - Audi A4 2.5 V6 tdi vibration on idle. - Hamsafar

I had one that did this but not too bad - but enough to take the shine off it.

For other reasons, I replaced (amongst other things) injection pump and cam belt which I timed up 100.00% spot on - in the end, I decided it was probably worn injectors.

These V6s were rather noisy and agricultural at idle, the later 2.7 & 3.0 V6s are much, much better lumps.

Edited by Hamsafar on 22/07/2013 at 23:00

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Tue 23 Jul 2013 09:45
Audi A4 B7 - Audi A4 2.5 V6 tdi vibration on idle. - Hildo1
Did it run fine apart from the idle for you? Or could you feel it when driving?
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Tue 23 Jul 2013 09:44
Audi A4 B7 - Audi A4 2.5 V6 tdi vibration on idle. - Hildo1
Hi thanks for the reply , ill give that a go thank you , it's frustrating more than anything as when I pull off I don't feel anything and the clutch seems like it has loads of life in it. I had an issue with it when I bought it as it was struggling to start first time, I got the fuel pump timing checked and that was out ever so slightly we caused it to smoke on start up, sorted that now but had VAG com on here and nothing comes up about the idle. Ill give this ago and be in touch cheers.
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