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| Xflow |
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Age: 36 Posts: 721 Joined: 31st Dec 2005 Ride: EF V8 Futura, 180sx Location: Brisbane, Burpengary |
Hey guys
i just did a compression test on my engine and i got (AU I6 engine) Cylinder.......Dry.............Wet 1...............200psi.........275psi 2...............195psi.........280psi 3...............210psi.........320psi 4...............200psi.........275psi 5...............200psi.........230psi 6...............180psi.........250psi I thought about 200 was good for your engine but i noticed my cylinder 6 down a pinch but correct me if im wrong when you do a wet compression test it should be about the same and if it goes up then it the rings are failing????
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| gogetta |
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what do u mean by "wet"
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| Xflow |
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Age: 36 Posts: 721 Joined: 31st Dec 2005 Ride: EF V8 Futura, 180sx Location: Brisbane, Burpengary |
wet you pour oil into chamber and helps rings seal better
http://www.geocities.com/dsmgrrrl/FAQs/compression.htm if you read threw here it explains wet compression test
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| limited |
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its always going to seal better with oil on the rings, if you want i can post up specs for compresssion for all engines on tuesday night after work, will have to look in the workshop manuals and get some figures
just out of curiosity, is there a reason why you checked compressions?
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| Disco Frank |
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iirc around 10-15% is tolerated between all cylinders
i hope u did the test on a cold engine
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| TROYMAN |
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hi
when i did a dry compression test on my au engine it had 210 psi on each cyl.. isnt a wet test known as a test with full throttle"fuel/air" and a dry test is closed throttle.? afaik you normally use oil if you have a low result to see if you loose pressure through the rings still you got to be happy with that... |
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| snap0964 |
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Disco Frank wrote: i hope u did the test on a cold engine Shouldn't the engine be at normal operating temp ??TROYMAN wrote: isnt a wet test known as a test with full throttle"fuel/air" and a dry test is closed throttle.? My understanding is that the throttle should be at WOT when cranking for compression.
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| Disco Frank |
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snap0964 wrote: Disco Frank wrote: i hope u did the test on a cold engine Shouldn't the engine be at normal operating temp ??TROYMAN wrote: isnt a wet test known as a test with full throttle"fuel/air" and a dry test is closed throttle.? My understanding is that the throttle should be at WOT when cranking for compression.not 100% on the op temp... as for the WOT it does ring a bell
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| Xflow |
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Age: 36 Posts: 721 Joined: 31st Dec 2005 Ride: EF V8 Futura, 180sx Location: Brisbane, Burpengary |
I was taught to do compression test at operating temperature when everything expanded to it correct positions. not when pistons are cold and they haven't expanded.
also all tests are to be done with WOT or your going to get a manifold vacuum and your results will start good on cylinder 1 then get s**t and allows full air flow into chamber to get true compression test not a restricted. i found my of Ford EF Gregory's book and it also says get engine up to running temp and WOT when your going to do compression test also oil test to assist in compression ring sealing and i herd that if the results vary more then something like 30psi from dry to wet then your ring are on there way out i would do a leak down test but i don't have the tool which i think i might invest in some time this week anyone noticed the compression on cylinder 3??? Cylinder.......Dry.............Wet 1...............200psi.........275psi 2...............195psi.........280psi 3...............210psi.........320psi 4...............200psi.........275psi 5...............200psi.........230psi 6...............180psi.........250psi it not that far off from being a diesel compression LOL hows my con rod going
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| tickford_6 |
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Posts: 6449 Joined: 11th Nov 2004 |
Xflow wrote: I was taught to do compression test at operating temperature when everything expanded to it correct positions. not when pistons are cold and they haven't expanded.
also all tests are to be done with WOT or your going to get a manifold vacuum and your results will start good on cylinder 1 then get s**t and allows full air flow into chamber to get true compression test not a restricted. i found my of Ford EF Gregory's book and it also says get engine up to running temp and WOT when your going to do compression test also oil test to assist in compression ring sealing and i herd that if the results vary more then something like 30psi from dry to wet then your ring are on there way out i would do a leak down test but i don't have the tool which i think i might invest in some time this week anyone noticed the compression on cylinder 3??? Cylinder.......Dry.............Wet 1...............200psi.........275psi 2...............195psi.........280psi 3...............210psi.........320psi 4...............200psi.........275psi 5...............200psi.........230psi 6...............180psi.........250psi it not that far off from being a diesel compression LOL hows my con rod going how much oil did you put in there? |
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| Xflow |
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Age: 36 Posts: 721 Joined: 31st Dec 2005 Ride: EF V8 Futura, 180sx Location: Brisbane, Burpengary |
3 squirts from oil can like the book say
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| cjh |
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I wonder what the carbon build-up is like in the cylinders??????
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| Xflow |
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Age: 36 Posts: 721 Joined: 31st Dec 2005 Ride: EF V8 Futura, 180sx Location: Brisbane, Burpengary |
cjh wrote: I wonder what the carbon build-up is like in the cylinders??????
Why do you ask that?? I use to run unleaded when i first got the car and now im onto preimum so id say it would be reasonally clean
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| cjh |
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Xflow wrote: cjh wrote: I wonder what the carbon build-up is like in the cylinders?????? Why do you ask that?? I use to run unleaded when i first got the car and now im onto preimum so id say it would be reasonally clean Carbon build up gives incorrect figures. Carbon buildup can come from oil consumption, ie: rings, valve stem seals, worn guides/valve stems, blowby going in through the PCV system (this is obvious when the throttle body is oiled up). Was the oil you used engine oil???? Did you wind the engine over several times after you put the oil in & before you did the comp test????
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| Xflow |
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Age: 36 Posts: 721 Joined: 31st Dec 2005 Ride: EF V8 Futura, 180sx Location: Brisbane, Burpengary |
Yer it was engine oil 20w50
and yes i cranked it a few seconds to spread the oil around the bore. and for build up in cylinder when i shined the pen light threw the spark plug hole it look reasonably good for piston top due to the use of premium fuels and ones and while some 100% octane fuel to them fun week ends at tracks. i kinda don't have a PCV valve due to i had issues with it pumping oil into the throttle body and burning it off. now that i put a super cheap rocker cover filter there and blocked the pipe to throttle body it runs so smooth don't smoke blue any more and up on power too.(the hose for the pcv was to thin and sucked flat and when reving and driving it starts to open and close and pumps oil threw LOL and i wonder where all the oil went LOL now i haven't had to top oil up since then)
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