No compression on cylinder 1

[katherine Goodrich]

Our A4 Avant 1.8 tfsi suddenly  ran rough could only achieve  20mph. RAC tried a coil which made  no difference.  Got towed to local garage who diagnosed a stuck valve. They say it will cost 6 or7 hours labour to strip the engine down to get to the valve and we would be better to pay them to put a recon engine in!? Not being mechanically  minded is this a sledge hammer to crack a nut or really would fixing a bent or stuck valve cost more to repair than an engine swap.

Anyone  else had this experience?  Should I go to my audi main dealer and risk their coasts?

[Magnet]

Hello Katherine,

Thanks for being in touch with the forum, and sorry to hear on your first post with us, that you are in difficulties with your car. 
A couple of points which may help you:- 

Even with no compression on one cylinder, it would be expected that the car’s performance would exceed 20mph - unless it’s gone into limp mode. 
Stuck valve? Uncommon in my book, and it must be asked that if this is correct - why? Has the car un low on oil, when was the oil and filter last change etc? 
If this is a belt driven engine, has the belt jumped a tooth, and you’ve been lucky enough to just bend the valves on one cylinder? 
Do you know when the belt was changed? 
I think I understand that the 6 to 7 hours labour is to just strip the engine to confirm / assess what is wrong, and does not include correcting the fault, and reassembly. If so, then the labour to fix and reassemble is likely to exceed 15 hours -? What is their VAT inclusive labour rate? 
If all the above is correct, then their reference to ‘reconditioned engine’ may make economic sense, but as I understand it, there are very few engine reconditioners left now, so where would you  get a ‘reconditioned engine’?, and if such a thing was readily available, then what would be the total cost to purchase, remove yours and refit the ‘new’ one. Compare this with the option of repairing yours. 
By reconditioned - they could well mean simply secondhand. 

If this were mine, I would be getting a second opinion on this car . 
Try a local independent in your area, and get the car transported there if you feel you have confidence in their reputation. 
Perhaps you could let us know how you get on. 
Kind regards,

Gareth. 
 

[ninjag]

Could it be the dreaded carbon build up causing a bad seal and low compression? 

Might also be worth checking your coolant, if you are losing any then it may be a bad head gasket. 

[Magnet]

Interesting points Graham, but to be realistic, I think both possible causes would have to be to the extreme on the severity scale to result in a total lack of compression on one cylinder. 
 

Hello Katherine,

Just wondered if any of the comments you have received so far have been of any help to you, and what your next move might be. 
Kind regards,

Gareth. 

[katherine Goodrich]

Hi Gareth & Ninjag,

Thank you for your posts. All I know so far is there's no compression at all on cylinder one. The car will start but goes straight into limp mode and it would be impossible to drive it now. It was towed to a local garage. It has a camchain & has only done 77,000 miles and has been serviced regularly and until this disaster it drove like a dream. The garage have now been in touch & have contacted an engine rebuild specialist. Apparently this engine rebuild business say this is a fairly common problem with Audi's that have a cam chain - that the chain becomes loose and it misses a groove. Audi have told me these cam chains are not a serviceable part unlike cam belts and they say they can last the life of a vehicle. So - the plan of action is that the local garage will take the head off on Wednesday and it will go to be rebuilt. This will cost about £1,100. It will come back with a new strengthened cam chain, new gaskets,  new tensioners. Then the local garage put it back together. The big concern though is if the the valve has damaged the piston, then it would apparently need a new engine! Fingers crossed........

[Magnet]

Hello Katherine, 

Interesting, and it sounds reasonable that the chain may have jumped a tooth, which could result in bent valves, but highly unusual to simply affect one cylinder. 
My logic did originally lead me to question whether we now have a simple valve timing error which results in a situation where both valves on No.1 cylinder are never in a combined two-closed -at-the-same-time situation, and hence lack of compression. Follow on logic may question if this would then only affect one cylinder. 
Longer story cut shorter:- I think I would be changing the chain, which includes resetting the valve timing, and testing the compressions again, rather than diving in straight away and taking the cylinder head off. 
If indeed the valves have hit the piston, then I would not necessarily write off the engine. 
Kind regards,

Gareth. 

[katherine Goodrich]

Hi, I thought I would give you an update on my A4 Avant. Our local garage stripped the head down and found that a spring on one of the inlet valves in cylinder one had broken, causing no combustion and therefore zero compression. It was nothing to do with the cam chain! This explains why only one cylinder was affected and why the engine had NO power. The head is going to an engine specialist on Saturday to be fully reconditioned and will basically be returned like a brand new head, complete with new strengthened timing chain, all new gaskets and seals, etc. Hopefully the bill won't be over £1,200 all in.  I love Audi's! I have a 21 year old Audi TT Mark 1 Quattro Coupe 1800 225bhp and a 9 Year old Mark 2 Audi TT 1.8 S Line TFSI. I am SO relieved about the diagnosis of the A4! I went to the Audi Beaulieu event as I'm such an enthusiast! Thank you for your input!