I think my 4.2TDI is dead - any advice ?

[podgee]

I have a 2006 A8 4.2TDI. Have had it for nearly 4 years now. Have maintained it meticulously and no expense has been spared on servicing etc - full Audi service history. It has approx 230k kms and until now has been going like a clock. Best car I've ever owned.

A couple of weeks ago, when it'd get hot (town traffic or leaving it idling), the car would go into limp mode. No flashing lights or warnings to say so, there'd just be no power above 1.5k rpm. Left it in the garage and they couldnt find anything. There was nothing logged in terms of errors when they scanned it. They gave it back to me and told me to bring it in if it happened again. Well it did happen again only this time accompanied by really rough running to the point that the car was shaking. Something felt off or out of balance in the engine internals.

So it's in the garage now. They are saying it's likely to be a spring or valve, which means an engine out job. This apparently means many hours to drop the engine, split the gearbox etc to remove the cams as "everything is below the cams". To embark on this, it'll probably be a few grand in Euros and just replacing one valve or spring, God know what valve or spring will go next - bearing in mind the mileage. They are suggesting a reconditioned engine. I have no idea what to do! I love the car but economics must prevail:-

Option One - Drop the engine and replace the valve / spring or whatever they find is wrong - maybe 2 or 3 grand
Option Two - Drop the engine and replace it with a recon unit - maybe 6k or so
Option Three - what is it ??

The car is probably, if it was in full working order, only worth about 8k (euros). Any advice or view on what I should / shouldnt do ?

Much obliged!
P

[Scott K]

Has it been to Audi or a specialist? Think you need a second opinion. What are they scanning with if its not at Audi?

[zollaf]

if its gone into limp mode then it will flag a code. i would guess they are using a generic obd reader which wont find the code. get it to someone that knows these cars, like a main delaer or specialsit.

[podgee]

Audi Service Agent - they've looked after the car from day one so I do trust them. Maybe overly so. Perhaps a second opinion then ?

P

[EG-4.0TDI]

Sorry to hear this. Engine drop and gearbox split to do timing chains was about 30 hours of labour if that helps (25 of which is engine drop and gearbox split - pretty much everything forward of the rear diff has to be dropped).

Anything cam or valve related is engine out - timing issues can be diagnosed with engine in situ by measuring the cam angles (there is a special Audi tool for this which is very expensive at about £400 so very few dealers carry one - it works by examining the cams after removing the fuel rails and cam covers to gain access which is about 4 hours).

Question for you: when you say 'reconditioned engine' is this a short engine? ie do they re-use all of your ancillaries (turbos etc)? My point being that the most likely source of future expense is ancillary problems rather than the block/internals/chain drives. At that mileage it would be uneconomic not to do some other jobs whilst access is possible for example: thermostat, checking the health of the turbos, EGT sensors, high pressure fuel pump belt, alternator and so on. Basically doing the things where the parts are not ruinously expensive but the labour would be cripplingly expensive if they went wrong later. You really don't want to pull the engine twice - once is enough in any lifetime. I ended up adding £1500 from ancillary work/preventative maintenance when I had the engine dropped.

You might be better looking for a second hand lower mileage whole engine (ie with ancillaries) and bolting it in - would probably save a lot of labour moving all the bits onto a recon engine as well.

[podgee]

Hi EG

Firstly many thanks for taking the time to put such a reply together - it is much appreciated. With regard to the reconditioned engine, I presume it'd be a short engine, so your point is fully taken in terms of replacing the affordable anciliaries. Can I ask a few questions please ?

1. The 30 hours for the drop and split - is this just for the drop and split and if so what do you reckon in terms of hours to put it all back in again ?
2. Is it possible to do a compression test with engine in situ ? Would this help in the diagnosis ? (I could be clutching at straws here!)

I think it is gradually starting to dawn on me though, that I'm going to have to ship the car on. It'll surely be worth a few quid to someone who'd be sufficiently skilled and prepared to do the work themselves ?

Thanks again
P

[EG-4.0TDI]

Hi Podgee,

Pleasure and sorry it's not good news. The 30 hours was for engine drop, gearbox split, replace timing chains and tensioners, and put it all back together and re-install. I don't know exactly how much of that related to timing chains but I would guess the drop, split, reinstall was in the region of 20-25 of those hours. Just dropping the gearbox (ie leaving the engine in situ) is about 16 to remove and re-install.

I would have thought that compression test should be perfectly possible with engine in situ, essentially it's going to involve removing fuel injectors or glow plugs and plugging a pressure gauge in their place. Given the injectors and glow plugs can all be changed with the engine in place it would seem reasonable to conclude that they ought to be able to pressure test each cylinder with the engine in the car.

Sadly, I would have thought that the most likely source of value for the car would be a vehicle breaker as there will be reasonable value in its parts (less the stock holding cost for the time it will take to sell them).

I suspect it won't be economic to fix in that, if one goes through the options:

1 'New whole engine' - guess 20k parts, plus 25 hours labour to fit -> 22,5k
2 'Recon short' - guess 3k part, plus 25 hours to fit, plus ancilliary swap over and coding say 8 hours, plus replace any dodgy ancillaries -> 9k?
3 'Fix current' - 25 hours labour to get lump out and back, say another 5 to strip heads/diagnose and allow another 10 to fix whatever it was, parts for what went wrong, parts for secondary damage, replace anything dodgy -> 7/8k?
4 'Breaker whole engine' - guess 3-4k part, 25 hours to fit -> 5/6k?

The viability of 2 and 3 will require a judgement call as to how skilled you believe your dealer is at heavy duty work? Ie how many engines have they pulled and stripped (as opposed to doing oil changes and cambelt changes on 2.0tdis)? The other danger with option 3 is that you spend a lot of money diagnosing the fact that the engine is not economic to repair (eg something's dropped into a cylinder and scored a bore) before then having to get another engine or have your car collected in pieces.

If they're really sure that something horrific has gone wrong deep in the internals then 4 may be the least-worst option if you can find a lower mileage one crated up and ready to go. Or it's time to move it on and start again...

[rob1976]

Sad to hear that your engine has such issues. Infact I think this is the first post I have seen regarding the 4.2 tdi with this kind of fault. There are susposed to be bullet proof! Yours having only covered 160,000 miles shoud be in it prime and give you that millage again.

I hope it turns out to be just a MAF or a simular fault, have another garage or someone close to you on this site who has VCDS to give it a second opinion.

Its got me worrying about mine now!

[rob1976]

What happened with the diagnotic/fault finding? did you get to the bottom of your engine trouble?