Mudsport96
Full Access Member
Here is a video of a compression and leak down test. The leak down procedure is close to the end of the video.
Compression and leak down test
Compression and leak down test
Oil Consumption
- Thread starter nonickatall
- Start date
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nonickatall
Full Access Member
That what make me concerned is that i have a loose of compression in this cylinder.
I checked the car for leaks, but i have no spots on the ground and i have no stains which a typical for coolant leaks. But i can fill 2 Liter water in 250 miles. But as well i dont see really white steam in the exhaust.
I checked the car for leaks, but i have no spots on the ground and i have no stains which a typical for coolant leaks. But i can fill 2 Liter water in 250 miles. But as well i dont see really white steam in the exhaust.
Recommend doing a wet compression test to determine if the rings are the cause, and the air leakdown test.
Also, you could check for exhaust gas in the coolant:
Also, you could check for exhaust gas in the coolant:
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nonickatall
Full Access Member
So now I'm completely confused.
I did a compression test again on cylinder 5. Result: 12 bar, which is about 174 psi, then a wet compression test, which was 13.5 bar, so about 195 psi, which would indicate the piston rings.
Then I did a pressure drop test which was under 5% which is extremely good.
I then did a coolant Co² test which came back negative.
So I think that the cylinder head gasket should be ok and the valves are tight.
The oil consumption definitely comes from the valve stem seals.
But the bad compression and the loss of coolant?
I did a compression test again on cylinder 5. Result: 12 bar, which is about 174 psi, then a wet compression test, which was 13.5 bar, so about 195 psi, which would indicate the piston rings.
Then I did a pressure drop test which was under 5% which is extremely good.
I then did a coolant Co² test which came back negative.
So I think that the cylinder head gasket should be ok and the valves are tight.
The oil consumption definitely comes from the valve stem seals.
But the bad compression and the loss of coolant?
OP
OP
nonickatall
Full Access Member
So I've thought the whole thing through and think that my poor compression on one cylinder may be due to carbon on the piston rings, especially since the bottom of the piston ring has a relatively large amount of carbon, which in my opinion comes from the leaky valve stem seals.
So I'll replace the valve stem seal and treat the cylinder with an oil carbon primer and see what happens.
Then there is still the problem with the loss of coolant and I have to look at whether I might have a leak somewhere in the cooling system.
So I'll replace the valve stem seal and treat the cylinder with an oil carbon primer and see what happens.
Then there is still the problem with the loss of coolant and I have to look at whether I might have a leak somewhere in the cooling system.
Mudsport96
Full Access Member
I think something you should invest in also, is an oil catch can. It goes I line between the pcv valve and the intake manifold. I will capture and excessive oil vapors and not allow them to be burned.
Catch can on Amazon
I love mine. On the Tahoe it collects about 250ml every 4800km. I just unscrew it and dump it out. The Silverado has one as well and it collects 250ml every 1600km, but it also has 676,000km on the engine now so it has the right to be worn out.
Catch can on Amazon
I love mine. On the Tahoe it collects about 250ml every 4800km. I just unscrew it and dump it out. The Silverado has one as well and it collects 250ml every 1600km, but it also has 676,000km on the engine now so it has the right to be worn out.
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