Technical Head gasket, piston ring or sticking valve problem?

[shiningliao]

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.

https://www.fiatforum.com/stilo-technical/159268-jtd-stlio-sick-white-smoke-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)

 

[Argonought]

Re: Head gasket, piston ring or sticking volve problem?

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.

 

[fiat brava jtd elx 105]

Re: Head gasket, piston ring or sticking volve problem?

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

 

[Yazza54]

Re: Head gasket, piston ring or sticking volve problem?

remove the spark plug

It's a diesel..

 

[ABZSTILO]

Re: Head gasket, piston ring or sticking volve problem?

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

 

[fiat brava jtd elx 105]

Re: Head gasket, piston ring or sticking volve problem?

sorry i meant remove the glow plug fromt the suspect cylinder

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

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.

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

How about a sticking piston ring? Is it possible?

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

Off to a delaer with it I suspect

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.

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

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

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)

 

[PNL]

Re: Head gasket, piston ring or sticking volve problem?

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..

 

[Argonought]

Re: Head gasket, piston ring or sticking volve problem?

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

How about a sticking piston ring? Is it possible?

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

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

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..

Do you mean this one?

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

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

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

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.

 

[Argonought]

Re: Head gasket, piston ring or sticking volve problem?

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?

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

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!

 

[cris1117]

Re: Head gasket, piston ring or sticking volve problem?

Hi All
Shiningliao
When you say you have pressure from the oil filler cap the question is how much pressure.
When the engine is cold it should be about the same as blowing hard on your hand, this would be normal, can you see exhaust or diesel vapour coming from the filler cap.
If this had been a petrol engine I would go along with HG theory but in my experience Diesels don’t reseal themselves just by heat expansion they produce too much pressure, when the HG blows they go all the way.
O.K I think the easiest way forward for you is to isolate the problem cylinder this will tell you if it is head gasket or not.
Not sure of the set up on the 1.9 jtd so will speak from experience of bigger diesels.
If each individual injector has its own fuel pipe you fire the engine up and loosen the first injector pipe half a turn you should hear the engine falter and run even worse than it is now, if so retighten it and move on to the next one, when you reach the cylinder with the blow it will make no difference when you loosen the pipe the engine will stay the same.
The other way is to remove the glow plugs one at a time and fire the engine up it will be noisy but the same thing will happen when you get to the bad cylinder it will run as it is now.
My money is still on pre heat problem have you investigated that?
I would hate to see you pay £500 for a new HG and all the garage does is replace the glow plugs.
What mileage you got on the car?

 

[Steely]

Re: Head gasket, piston ring or sticking volve problem?

Heavy breathing of most engines i would relate to a compression ring, the oil scraper ring will still be doing its job so shouldn't smoke due to oil getting past the rings, since diesels have a high compression ration compared to petrols usually 18:1 to 23:1 the missing and smoking in the morning i would put down to unburnt diesel, once up to temp its fireing but only just, basically down to low compression, since diesels rely on compression ignition, the compression from the cylinder is forcing past a ring building up crankcase pressure,


compression test woulld be the best way! hoopefully uniform across the cylinders

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

.......

Thanks for your comment. I haven't put my car into garage yet... as the problem goes away after warm up.

I haven't digest all of your comment. I'll study it a bit more later on..

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

Heavy breathing of most engines i would relate to a compression ring, the oil scraper ring will still be doing its job so shouldn't smoke due to oil getting past the rings, since diesels have a high compression ration compared to petrols usually 18:1 to 23:1 the missing and smoking in the morning i would put down to unburnt diesel, once up to temp its fireing but only just, basically down to low compression, since diesels rely on compression ignition, the compression from the cylinder is forcing past a ring building up crankcase pressure,


compression test woulld be the best way! hoopefully uniform across the cylinders

One of the reason I haven't put the car into garage is I suspect the failure of piston ring. This will cost a lot more than just £500.

Is it possible to do the compression test by myself? How?

Is it only FIAT dealer can do the compression test? Or any general garage will do?

 

[shiningliao]

Re: Head gasket, piston ring or sticking volve problem?

I have changed the oil recently and the situation is a bit different from the past.

1). The car doesn't smoke when it's cold.
2). Engine seems lost power for a very short time when I try to drive at cold temperature. Once warm up. It's gone. The sympton just like fuel been cut off for 0.1 second.
3). Engine seems not powerful enough when going up hill even when engine has warm up.
4). The blowing air from the oil cap only happen when RPM under 1000.