Buying 2008 A8 4.2 TDI

[phi__r]

Hi Forum users,

I'm after some advice. I'm about to take the plunge and buy a used 4.2 A8 TDI with 73k on the clock (~£15k).

It looks and drives well, but is there anything I should be aware of when buying one of these cars? The purchase will potentially be from from a private garage.

Cheers

Jon

[EG-4.0TDI]

Hi,

Welcome! I have a 4.0TDI so can't comment directly on 4.2, but I dare say that some of the things will follow across:

Look closely for any warning lights would be the top tip. Any warning light needs proper investigation as many of them cover a multitude of sins.

Check tyre wear - should be broadly even across the tyres. Any funny wear means alignment needs fixing - which is fine unless they then find anything ceased which can get expensive quite quickly.

Front brakes are expensive - £500 for discs and pads so check the life in them. Rears about £350 and must be done by a dealer or specialist as you need a computer to retract the electronic handbrake.

- Front suspension joints (any creaks, squeeks, knocks). Beware, some of these can be expensive - track rod ends for example get very pricey (like £800) because you might as well do all 4 of them because of the cost of alignment and bump adjustment. Individual arms aren't too bad at circa £200 though.
- Air compressor relay (wears out then leaves the air compressor running until it burns out). Quick preventative maintenance fix and worth doing for £100 as a new compressor is over £1000. Watch out for any illuminated suspension lights.
- Flashing glow plug light - can be about a million things and none of them are cheap. Known issues include the intake manifold swirl flaps (£1k each side as you have to have the whole manifold), thrust sensors (£400), and variable vane turbos ceasing up (at least £2k). Take the cover off the engine and look at the intake manifolds (two big black plastic things running along the top of each side of the engine). Check for any oil leaks around them as you can't get the seals just the whole units at £1k each.
- Listen very carefully to cold startup - any clattering or anything that sounds like a hammer on metal walk away. Quite a few cases of worn timing chain tensioners (certainly true on 3.0 and 4.0 but not sure about 4.2 in fairness) which is an engine out job to fix (wrong side of £4k). Be wary of anything that's had 20k 'long life' service intervals (check the history) as this exacerbates the issues - including being detrimental to turbo life. Turbos can be seriously expensive as well - if I recall correctly at least one of them requires dropping the engine to gain access.
- Check ALL the electrics work and don't do anything peculiar (for example switching randomly into German, or draining the battery). Rare but can be very time consuming to diagnose and hence expensive to fix.
- Dead batteries are a nuisance as, in theory at least, new ones need coding into the ECU that manages power distribution so you're into £300 odd.
- Any oil leaks from the transmission or engine are worth investigating as well - can range from irrelevant to seriously unfunny (rear main oil seal is £1600 as gearbox out for example).

Keep some budget aside for random things going wrong which, in my experience is about £2-3k per annum over and above the usual consumables such as brakes and tyres.

Now, that lot said, others on here have had no issues at all so it's a question of luck (and maybe how pedantic one is about wanting everything the be 'right'!) so I'm painting a worst case scenario and I suspect my experience is of more trouble than average. For what it's worth, however, I will be buying another one after this as there simply isn't anything better - when they work they are brilliant and everything at this class can throw punchy bills.

Good luck and keep us posted!

E

[snapdragon]

EG-4.0TDI gives excellent advice so write them into a list as they are very important and easy to forget when you are looking at a car.

The only commentary on this would be EG-4.0TDI 's prices look like Audi dealer open-wallet prices, so don't let them put you off too much, you can fix many problems by searching these forums, e.g. suspension compressor relay is £6 for pattern, £14 for VAG part and 15 minutes of your time.

I'm sure that if you do buy one, get a VCDS any old laptop too....
http://store.ross-tech.com/shop/VCHUC.html
Sadly, it is rather more expensive these days due to the USD-GBP exchange rate.

[EG-4.0TDI]

Fair point there Snapdragon - they are indeed main dealer prices. As you rightly say, there are cheaper ways of doing lots of it.

Personally, I tend to end up paying for the convenience and also the knowledge that if they get it wrong (which seems quite possible given the complexity of these cars) they put it right without fuss or issue.

Wishing i had done the relay fix myself though - only found the DIY about a week after I'd instructed the dealer!

[killzone]

Great advice, search out an Indy , I have two Audi main dealers in my area and an exallent Indy , they worked on my mercs first call for me, just need to decide 4.0 or 3.0 tdi.