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

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

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..

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?

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.

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compression tester, it does sound very much like heavy breathing to me, the only reason i can think that it happens sub 1000 rpm, is down to the fact the compression cycles are longer so give it time too seep past the rings, once up and running, the compression stroke is so short time wise it doesn't give it chance to blow by,,,

a good garage should be able to do a compression test,


but as PNL mentioned, I would recommend doing a forte flush, try cheapest options first, it could be a stuck compression ring, but it could be many things, scoured piston/cylinder, slapping piston, but its all speculation so dont jump to conclusions! i as lead to believe i needed a new body computer for the stilo and all it was, was a poxy parking sensor control!

Cheers!

I have changed the oil with engine flush prior new oil. Problem still there but seems a bit different.

Here is my summary of symptons and the guess of the root cause with help from everyone:

Sympton 1). Air coming out from oil cap when RPM < 1000
==> Piston ring problem. Only when RPM < 1000 as compression cycle time is long enough to let the air seep out

Sympton 2). White/Grey-ish smoke in the morning when engine is cold. (so far, happen three times only)
==> Oil seep into cylinder over night, head gasket failure

Sympton 3). Engine seems lack of power for 0.1 second at 1800 RPM. Specially when engine is cold.
Theory 1==> Turbo is on its way out.
Theory 2==> Air get into crankshaft, oil evaporate into turbo intake. When turbo kick in at 1800 RPM. Too much oil into cylinder cause non-full combustion, hence lack of power. When engine is hot, all the oil are burt out. Back to normal.

Sympton 4). Losing oil slowly. Obvious around turbo.

Sympton 5). Black smoke when accerate fast.
==> Common sympton for all diesel engine?

Other info.
a). Fiat dealer use computer to diagnose engine. Nothing wrong. They only guess it's head gasket failure. Need to open engine to check ;-(
==> I think this should rule out glow plug problem. Otherwise, it should pick up from the computer diagnose.
b). No over heat, no lost of coolant at all.

have you had the air filter out?? check for engine oil contamination, this would be caused by blowby on the piston rings, usually you will get a very slight emulsion...


just dont make any quick decisions, sometimes its better to stand back and look at it another day,,, and im sure many with help on here, !

this is a way out theory but still check the air flow metre and waste gate on the turbo. as the problem is worse when cold just check the dash lights and see if a glow plug warning light flashes for more than 30 seconds when starting.
if yes the glow plugs mayb on there way out as they dont last forever. If u do a compreesion test just b careful m8 as its a bit more dangerous than doing a petrol model.

I've checked the air filter. Nothing wrong with it. However I did see some little oil leak around the intake pipe from turbo.

As for the oil. There is no water (coolant) in the oil. No sign of losing coolant at all. I think the coolant system is perfectly contained. In such case, could broken piston ring cause the emulsion as well?

I have found a way to reproduce the smoky sympton. It happened when:

1). Car parked overnight.
2). Rev the engine right after start up.
- If I wait for the engine to run at idle speed for couple minutes, the smoky sympton won't come out.


Previously, I thought it's head gasket fail. Oil leak into cylinder. So the sympton should be: The longer I park the car, the more smoke I got.

This is not true. To get lots of smoke, simply start the car and rev engine immediately. On the other hand, if I let the engine run at idle speed for 5 minutes, smoke problem won't come out.

I am getting to feel this is something to do with turbo. Or... to the worse case. Both head gasket failure and turbo problem

Glow plug warning light is normal. What is turbo waste gate for? Thanks.

Is that final a summation for this thread then

You've only mentioned two things which I would question:

• High oil consumption (should be low on a JTD)
• Weak on hills (this is very very wrong as climbing ability of a JTD is quite simply awesome)

Forget about the turbo waste gate - you haven't got one

What does the boost control valve actuate then?

I think you will find it is the wastegate.