How mechanic diagnose piston rings is KO!

[KCi]

Hi Guys,

I'm driving 4 years old 1.5 Wira and I keep losing my engine oils these days. It had become more apparent days by days. At first, i'm suspecting it was Mobil Semi-Synt was too thin to handle it as I am travelling once a month from KL-PG and sometimes on spirited drive (redline :rolleyes: ). The rate of Mobil S oil losing is still bearable.

Since I thought it was Mobil S, then I changed to Petronas 15W-50 which more thicker than previous one. Shit, this is more worse, the engine oil dipped to minimum level after 2 weeks of changing. In this 2 weeks time, as usual, I had done outstation travel and again, some spirited drive. This kind of situation is really puzzling me.

FYI, I'm still haven't consulted any mechanic. But I'm quite sure they all will say your valve head or piston rings are not doing their job well and need to change. This is not good (at least to me) since they are not doing extra testing to confirm that.

So guys, what is your inputs on this matter? What or how the mechanic will do before they really can confirm the valve head or piston rings kong?

Hope you guys can help me out here! B)
Thanks.

KCi

 

[Supachip]

They can do a cylinder compression test to verify if it's coming from the rings or the valve guide.

Vacuum test can be carried out as well to check if all the valves are sealing properly. :)

 

[KCi]

Supachip,

Thanks for the inputs. Is these mentioned tests can be carry out at any normal workshop or do I have to go to specifically larger workshop to do that? What process of these tests go thru actually? ^_^

 

[Supachip]

Compression test should be easily carried out in all workshop using compression gauge. Just plug the gauge into the sparkplug hole one by one and start the engine. Compression should be around 13 to 15 bars.

Whereas if the compression is ok, normall should be the valve guide. Mechanic can check if there's loads of carbon soot at the back surface of valve stem.

Sorry, the vacuum check is only meant for checking bent valves (knocked piston).

Cheers :)

 

[Boink Boink]

Hey Bro,

Just curious. Do you keep it a red line for long periods? you did mention you red line alot. Do you think yout oil could be going out your oil breather valve?
:blink:

 

[KCi]

Supachip,

Thanks for the info. I need to check this asap as losing oil means losing $$$.

 

[ocean]

Originally posted by Supachip@Jan 17 2005, 11:30
Compression test should be easily carried out in all workshop using compression gauge. Just plug the gauge into the sparkplug hole one by one and start the engine. Compression should be around 13 to 15 bars.

Whereas if the compression is ok, normall should be the valve guide. Mechanic can check if there's loads of carbon soot at the back surface of valve stem.

Sorry, the vacuum check is only meant for checking bent valves (knocked piston).

Cheers :)

:o Woo .. I think I should do a compression test on my engine also ..
Very good info .. Thanks Supachip ...

That day I took out my 4-2-1 pipe to check my valve stem .. I found my valves stem had carbon (same with the carbon shown at below) .. I found my plug had carbon which caused by oil fouled. Horse Power of car still OK .. Just sometime notice got bit white smoke from rear exhaust (in hot engine condition) ..

:( sad ... recently quite poor ...

http://img126.exs.cx/img126/1513/plug5vf.jpg
I attached the picture of plug as above

this sample i downloaded from internet .. i didn't shoot my actual plug's sample..
the case is similar .. but mine one the carbon is on the red circle area ..

Possible the leak only on the valves site ? Does the piston ring site also effected?
please help .. thanks

 

[KCi]

Boink,

Nope. Normally I just shift when RPM near redline. Mostly during 1st and 2nd gear change. Won't dare to hold it too long as 4G15 is not a strong block either.

Is there any oil breather in 4G15 engine? Where is it located?

 

[ocean]

Hi, KCI
Did you check your plug's leg ?? how does it looks like ??
Mine one worse .. Like the picture I attached ...

 

[Supachip]

You suspected that the engine oil went into combustion chamber through PCV system (breather)?

I think that will only happen if the oil is overfilled gua.

4G15 (FI) engine, I think PCV is the rubber hose attached to the intake pipe. normallly there's a one way valve to prevent this.

If the breather is blocked, engine oil will seep out from crankcase coz too much pressure in within.

:) :)

 

[KCi]

Ocean,

I just got my spark plug changed. The plug legs look normal and hardly any oil foul. Yeah, need to get the compression test asap before losing any more precious engine oil.

 

[KCi]

Supachip,

Great info here. Since I don't see any oil spill in my engine bay, I presume I can rule this out.

Roughly how much do I need fork out if it turn out to be worn piston rings and valve head? Any ideas?

 

[ocean]

I have no idea how and where the oil goes into the cylinders .. What I know when i check on my plug's leg, it shown oil fouled.

Really headache ..
How much does it cost to run a compression test in garage?
Does the compression test kit expensive? If cheaper that will consider buy one keep at home .. no waste coz can share with my brother's car to test the compression rate ..

:lol: Just checked on the compression test technical site .. really useful .. they recommended use "wet compression test" if the cylinders run in low compression status to check whether piston ring or valves problem ... ;)

 

[InitialD]

If your piston rings have gone bad, then a few things can happen:
1) some of the heat or flame from the combustion process can sip past the bad rings and fry the engine oil in the crankcase. That's how it "makan" engine oil

2) lost of power because of bad piston rings not doing its job of properly sealing the cylinder for the combustion process....hence lost of power and increase in fuel consumption.

 

[szekeiemme]

last time my case if .. black oil same prob like urs la.. but my car prob is oni 3 piston working oni.. 1 patah... n u check got black/gray smoke coming out from exhaust anot..

 

[ocean]

Originally posted by szekeiemme@Jan 18 2005, 13:47
last time my case if .. black oil same prob like urs la.. but my car prob is oni 3 piston working oni.. 1 patah... n u check got black/gray smoke coming out from exhaust anot..

:o 3 pistons running ?? the whole engine sure shaking very serious right ??
Em.. I also not know .. morning when i start the car .. just feel like 3 pistons running only .. after a while .. OK .. no problem ...

 

[KCi]

Hi Guys,

Latest news!! I had done engine compression test and the result there are worn cylinder at no.4 and no.2. (4G15 firing sequence 1-3-4-2). Both cylinder no.4 and no.2 recorded pretty low pressure with 100psi and 75psi each. While the rest are okay with 125psi and 130psi.

It could be the blown gasket between cylinder no.4 and no.2 but the difference between them is just too great. Hence, the culprit could either worn piston rings or valve heads. Anyway, still need to fork out big sum of money to get this fix (cham ler, need money for CNY too).

Roughy fixing cost is around RM700-RM900 depending on severity.

 

[ocean]

Originally posted by KCi@Jan 19 2005, 08:36
Hi Guys,

Latest news!! I had done engine compression test and the result there are worn cylinder at no.4 and no.2. (4G15 firing sequence 1-3-4-2). Both cylinder no.4 and no.2 recorded pretty low pressure with 100psi and 75psi each. While the rest are okay with 125psi and 130psi.

It could be the blown gasket between cylinder no.4 and no.2 but the difference between them is just too great. Hence, the culprit could either worn piston rings or valve heads. Anyway, still need to fork out big sum of money to get this fix (cham ler, need money for CNY too).

Roughy fixing cost is around RM700-RM900 depending on severity.

hi, Did you ask them to run the "wet compression test" or not? pour some oil into the cylinder 2 & 4 to temporary seal the ring if got leak. After that run the compression test again and record the result. If the result shown compression still low means not your ring problem, it is your valves problem. If the result shown compression high then it is your ring issue.

By the way .. How much they charge you for run this compression test?
We are same luck ... I also need money for this coming CNY .. :(

 

[KCi]

Hi Ocean,

Nope. They didn't run any wet compression test. Based on their experience, very rare cases are due to valve head. mostly due to the piston rings. anyway, once the engine is open up, they also can determine whether need to change the valve head later or sooner.

They are not charging me. It is just minor test and fast stuff. Most likely I will wait until all my piston worn out before I start rebuild the engine. To me, not worth it if it is only one piston ring KO. Yeah, I still can tolerate minor lost of power.....what the heck....$$$ come first.

 

[ocean]

Originally posted by KCi@Jan 19 2005, 10:03
Hi Ocean,

Nope. They didn't run any wet compression test. Based on their experience, very rare cases are due to valve head. mostly due to the piston rings. anyway, once the engine is open up, they also can determine whether need to change the valve head later or sooner.

They are not charging me. It is just minor test and fast stuff. Most likely I will wait until all my piston worn out before I start rebuild the engine. To me, not worth it if it is only one piston ring KO. Yeah, I still can tolerate minor lost of power.....what the heck....$$$ come first.

ic .. ic ... that's truth ... keep the money 1 st .. If the budget allow ... don't repair .. throw one MIVEC engine better .. hehe ... :lol: