(T) Head gasket, piston ring or sticking valve problem?

Hi everone,

Need you guys opinion again. In my previous thread, thanks to everyone's help and I have almost identified it's a head gasket problem.

http://www.fiatforum.com/stilo-techn...-any-idea.html

One thing worries me is... this could be the piston ring failure. Not the head gasket.

Here is the reason that I think it could be the piston ring failure.

1). Exhaust come out from the oil filling cap. (at idle speed only, once engine rev up, sympton gone)
2). No lost of coolant.
3). No over heat problem in the past.

If it's head gasket problem, engine should have been over-heated in the past. Due to no over heat problem, no lost of coolant problem... I think it's piston ring failure which means the fix cost will be much higher

What do you guys thing?

Could this problem caused by steaking volve? (My wishful thinging)

A sticking valve wont pressurize the crankcase - only cause low compression

Broken ring is I suppose a possibility but personally I've never heard of HG or ring failure on any JTD.

Compression test is obvious check but not sure how you do that. I guess Examiner my help by measuring starter motor load. Once low compression is shown then you could maybe remove the heater plug on the bad cylinder and also remove a good one and then compare the two. At the end of the day though, it's not going to solve your problem so you might as well get that head off.

It will be obvious if the gasket has failed once the head is removed.

YES this sounds like a piston ring sticking m8

do u kno your way around a car m8 if yes remove the spark plug from teh suspect cylinder and pour a tea sppon of oil into tht cylinder and put the spark plug back if this sorts the problem for a short while then its definatley the piston ring and need to be changed but then again the oil way release the ring sorting the problem kk

hope this helps

It's a diesel..

I believe he may have a hard job finding the spark plug as it's a diesel

Hence Argos' suggestion of bunging on the examiner is probably more reasoned.
However, the principal of removing a heater plug and a spark plug are similar although I suspect with a diesel the oil test would be less effective

Off to a delaer with it I suspect

sorry i meant remove the glow plug fromt the suspect cylinder

Thank you. I can forget about sticking valve for now.

How about a sticking piston ring? Is it possible?

Car been to the dealer. They cannot find the problem...

They only "guess" it's head gasket problem. Coolant get into cylinder... which is incorrect.

I found the exhaust get into the crankshaft but not sure if it's head gasket. If it's head gasket, £500 + VAT will do the job. I am happy for that.

However, if it's only sticking piston ring. Then I think it might be possible to fix it without open the engine up.

If it's broken piston ring, not worthy to fix it. I would guess it gonna cost nearly £1000. Then I would prefer to trade in for another car.

This is why I am trying to narrow down the problem and decide my next step economically.

A spoon of oil into problem cylinder to help the sticking piston ring.... this is a good suggestion.

However, I don't even know which cylinder cause the problem. Any idea to identify it? (Remove the glow plug on JTD were too difficult)

Ring could be cracked and thats why you have blow by..if its stuck[which you can't confirm] you could give it the forte treatment and that might free the ring..

If the car's been well maintained (good oil used) then I'd say it's unlikely so I'd put my money on HG.

The head may not need skimming (normally required when you've tried to push a valve through the head or after severe overheating which has warped the head) in which case the job should be under £500. You should however take expert advice on this.

Worst case - if HG good - ask the garage how much to simply put the head back on (obviously you'll need a new gasket). This is the amount you're risking.

I'd say it's worth the risk

Do you mean this one?

http://www.forteuk.co.uk/Oil_treatment.htm

Just think over again for some of the symptons:
- White (gray) smoke in the morning (sometimes) with engine misfiring.

I guess this means HGF at least. Only piston ring failure will NOT cause oil leak into cylinder overnight.

You say it runs fine when warm so difficult to see how rings can un-stick and then stick again when it cools (same applies to valves).

On the other hand this is common with a HG and I suspect it leaks when cold but seals when hot.

Clutching at straws I'm sure - but have you torqued up the bolts to correct value (and in correct sequence) when cold as I suggested at the start?

You are right for the above comments.

Torque up the head bolts is a good idea!