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3.0 V6 TDI timing chain broken - repair or sell car as is?

3.0 V6 TDI timing chain broken - repair or sell car as is?

Author
Discussion

AndiB

Original Poster:

4 posts

145 months

Wednesday 6th September
quotequote all
2009 A6 3.0 TDI Quattro 110,000 miles.
One cam is not rotating due to broken timing chain. Engine in car still. Garage unsure of the labour or work involved. We don't yet know whether there is piston or head damage.

Any experience of this? Any idea of the labour involved in engine out, investigate and then replace chain and if necessary fix the head?

Also I thought chains were meant to last. Why might it have broken?

I have owned the car from new, and always serviced on time with Audi for two years and trusted independent in following seven years.

This is our main car

Any advice much appreciated.

Thanks

E-bmw

2,816 posts

73 months

Wednesday 6th September
quotequote all
There WILL be valve/piston damage.

Cam-chains, like anything mechanical are not immune to failure, but they do not need periodical change like belts.

As you have owned & serviced it from new have you been in touch with Audi UK in case they offer assistance for your woes?

DuraAce

2,196 posts

81 months

Wednesday 6th September
quotequote all
It ain't going to be cheap!

Engine out, repair, back in - 20 hours labour easy I would say.
Parts required is impossible to say. You might get away with a few bent valves, worse case is the block/head is trash (unlikely unless the chain went at max rpm)

Suppose you have to weigh up what the car is worth to you vs repair costs....

227bhp

5,358 posts

49 months

Wednesday 6th September
quotequote all
Timing chain tensioners are known to fail prematurely on these letting the chain jump teeth, early ones are worse, They used better quality ones on the later models.
You're looking at big money, changing the chains themselves as per service is a big expensive job too, so don't blame yourself.

wormus

8,524 posts

124 months

Wednesday 6th September
quotequote all
If it were mine, I'd take it to an independent Audi specialist and ask them to take the head off for a look. You may be lucky but if not, a new engine according to eBay is about £2k. Either way you won't get much change from say £4K. Probably more.

An indie will be able to provide more accurate estimate so start there.
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stevieturbo

12,581 posts

168 months

Wednesday 6th September
quotequote all
Whatever you do...ensure whoever you take it to is both competent and trustworthy.

I've seen far too many morons tackle such jobs, and not only leave the car scrap...but also hitting customers with huge bills too, and all down to the garage being useless fkers.

But even a best case scenario here is going to be a large bill...worst case a huge one.

And chains can fail too, just bad luck really.

If the car was maybe only at idle when it happened, you might be incredibly lucky and have a smaller bill, but if you were driving at the time, more rpm's involved etc....it really could cause huge destruction.

Both actual engine damage, and consequential damage, eg turbos etc. So factor that worst case in too.

AndiB

Original Poster:

4 posts

145 months

Thanks all for your help and comments.

So I now have my car back fixed. The cause of the problem was a broken top timing chain. I will put some notes below for the benefit of others in the future.

The engine has four chains. One of which go to each over head cam. A common failure mode is for the top chain tensioner (which is hydraulic) to wear and the chain slap around, especially at start up when the oil is cold, and it to jump a sprocket or more causing bad timing. The ECU then refuses to work due to the timing problem. I was told that if it has jumped perhaps 4 or 5 teeth or less then there will probably be no damage to the head. Resolution would be to replace the top tensioner (or both as a precaution) which can in fact be done with the engine in the car and reset the timing.

In my case the chain had actually broken. It was engine out, replace top two and two tensioners, head off, check valves. The head was ok. The chain had failed with the roller disintegrating off the link pin. Perhaps these bits caused the chain to snap or not. Gearbox and sump came to look for the roll but it could not be found so is presumed to have left with last oil change. There was no sign of excess heat or poor lubrication. The garage said they rarely see failed top chains and have never seen a bottom chain go.

In total 25 hours labour, two chains and top tensionsers, head checked, head bolts, misc gaskets and cv boot, air con recharge, oil, filter, coolant, vehicle relocation... 3k inc VAT.

For me it made sense to repair as I have had the car since new and without repair it was effectively worthless.

btw. there was no significant noise heard before the chain broke as you might have heard if it had been a tensioner failure and the chain was slapping the cover.

I hope this helps someone in the future.

Andy


wormus

8,524 posts

124 months

sounds like a good result, albeit an expensive one. Guess it could have been much worse.