Compression Test
Thread Starter
Newbie
Joined: May 2010
Posts: 12
Likes: 0
From: Costa Rica
Compression Test
Hi guys from Evolutiom.net
Recently I make a compression test on my CN9A and this was the results
150 PSI
150 PSI
75 PSI
150 PSI
The weir part is that the car no smoke, 0 boost leak and I fell the it pulls very good.
I had some problems with crankcase( oil dip stick pop out), but i put dual catch can.
So, to discard everything before take a part the head to see what's going on inside I need some help from you guys.
Thanks for the help
Recently I make a compression test on my CN9A and this was the results
150 PSI
150 PSI
75 PSI
150 PSI
The weir part is that the car no smoke, 0 boost leak and I fell the it pulls very good.
I had some problems with crankcase( oil dip stick pop out), but i put dual catch can.
So, to discard everything before take a part the head to see what's going on inside I need some help from you guys.
Thanks for the help
Hi guys from Evolutiom.net
Recently I make a compression test on my CN9A and this was the results
150 PSI
150 PSI
75 PSI
150 PSI
The weir part is that the car no smoke, 0 boost leak and I fell the it pulls very good.
I had some problems with crankcase( oil dip stick pop out), but i put dual catch can.
So, to discard everything before take a part the head to see what's going on inside I need some help from you guys.
Thanks for the help
Recently I make a compression test on my CN9A and this was the results
150 PSI
150 PSI
75 PSI
150 PSI
The weir part is that the car no smoke, 0 boost leak and I fell the it pulls very good.
I had some problems with crankcase( oil dip stick pop out), but i put dual catch can.
So, to discard everything before take a part the head to see what's going on inside I need some help from you guys.
Thanks for the help
Thread Starter
Newbie
Joined: May 2010
Posts: 12
Likes: 0
From: Costa Rica
Before you start guessing at what's wrong, do a leakdown test, it will tell you if it is the pistons rings bad or the intake or exhaust valves not sealing. It would suck to change the rings when the valves was the problem or vice versa.
Newbie
Joined: May 2007
Posts: 92
Likes: 0
From: Oregon
I know this will sound crazy, but I've seen this happen on cars I've tested. Sometimes when removing the plugs carbon will drop down on the piston and when cranking can stick to a valve face not allowing the valve to seal completely. Leading you to think something is wrong. When I used to work on Audi/VW cars, this would happen often enough that I'd spin the plugs out 3 turns and start the car for a few seconds. I'd take that extra time to save time in the long run.
So before you take anything apart, now that you've taken the plugs out once, you probably don't have any carbon build up, if you did it's not there now. At least around the plug to head area. So run that test again. If you still get the same 75 psi squirt some engine oil on the piston and run the test again. If it goes up then it's rings, if not then it's valves.
A leak down test will provide you with more information though.
So before you take anything apart, now that you've taken the plugs out once, you probably don't have any carbon build up, if you did it's not there now. At least around the plug to head area. So run that test again. If you still get the same 75 psi squirt some engine oil on the piston and run the test again. If it goes up then it's rings, if not then it's valves.
A leak down test will provide you with more information though.
Thread Starter
Newbie
Joined: May 2010
Posts: 12
Likes: 0
From: Costa Rica
I know this will sound crazy, but I've seen this happen on cars I've tested. Sometimes when removing the plugs carbon will drop down on the piston and when cranking can stick to a valve face not allowing the valve to seal completely. Leading you to think something is wrong. When I used to work on Audi/VW cars, this would happen often enough that I'd spin the plugs out 3 turns and start the car for a few seconds. I'd take that extra time to save time in the long run.
So before you take anything apart, now that you've taken the plugs out once, you probably don't have any carbon build up, if you did it's not there now. At least around the plug to head area. So run that test again. If you still get the same 75 psi squirt some engine oil on the piston and run the test again. If it goes up then it's rings, if not then it's valves.
A leak down test will provide you with more information though.
So before you take anything apart, now that you've taken the plugs out once, you probably don't have any carbon build up, if you did it's not there now. At least around the plug to head area. So run that test again. If you still get the same 75 psi squirt some engine oil on the piston and run the test again. If it goes up then it's rings, if not then it's valves.
A leak down test will provide you with more information though.
Again thanks!!!
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I have the exact same results currrently... Im still roadracing the crap out of my car like that.. i took off my exhaust mani and saw oil reminents around that low comp cylinder, so i know mines low because of the rings.. been on low compression on this cylinder for 25k hard miles. Not saying u should, but ur ok for a little bit if u dont have time/money
