Emergency! Compression figures?
- Thread starter kaj
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dank GN
BlackArts Automotive (661)993-8277
- Joined
- Jan 11, 2009
- Messages
- 4,039
Mine are all around 130-140
dank GN
BlackArts Automotive (661)993-8277
- Joined
- Jan 11, 2009
- Messages
- 4,039
That's on a 90000 mile motor
ball park is perfect. my mileage is unknown.. but i just needed some type of reference. then i can concentrate on the numbers being equal. thanks!
dank GN
BlackArts Automotive (661)993-8277
- Joined
- Jan 11, 2009
- Messages
- 4,039
They should all be within 10% of eachother
correct.
does anyone know what number is normal for them to jump to after the first crank?
90-100ish?
C
coach
Guest
First off...disconnect the wire going to your ign module. Next crank it until it stops climbing. I just did a check on my 24k mile engine and all were 145-155, and I have beat the snot out of it.
:biggrin:
:biggrin:
yes, thank you. i know how to do the check. i just don't know what the numbers need to be. i'm trying to figure out where the needle should jump to initially, now that i know the peak number. and i am aware they need to be relatively equal on all cylinders.
C
coach
Guest
The needle could jump anywhere depending if its on a comp stroke or exhaust stroke, or intake stroke...
:biggrin:
GARY HARVEY
Member
- Joined
- Aug 17, 2001
- Messages
- 444
After a compression test..
You will get a better idea of the situation using a leak tester and testing at a warmed/hot temp, which is also positive for a compression test.
As for a percentage differential, keep in mind your history with other passes.
Have your times started to increase?
10% differential is (a little) on the problem side for a hot rod but acceptable for a daily driver.
Do you have any numbers from the first build as reference or time when first
(started) running this engine (bought or build spec info sheet)?
You will get a better idea of the situation using a leak tester and testing at a warmed/hot temp, which is also positive for a compression test.
As for a percentage differential, keep in mind your history with other passes.
Have your times started to increase?
10% differential is (a little) on the problem side for a hot rod but acceptable for a daily driver.
Do you have any numbers from the first build as reference or time when first
(started) running this engine (bought or build spec info sheet)?
You will get a better idea of the situation using a leak tester and testing at a warmed/hot temp, which is also positive for a compression test.
As for a percentage differential, keep in mind your history with other passes.
Have your times started to increase?
10% differential is (a little) on the problem side for a hot rod but acceptable for a daily driver.
I do a leak-down if the compression test is irregular. I have a comp test gauge in my garage. A leak-down requires a drive to the shop, which I am currently unable to do.
Correct. I've been doing these for years. Very familiar with the process.
Is there a specific way to kill the fuel pump? I was just gonna pull a fuse.
Pittsburghkid
Displacement Replacement.
- Joined
- Mar 22, 2009
- Messages
- 1,774
just unplug the ecm from the positive battery cable, or just pull the plug right underneath the license plate under the rear bumper.
Reply
My preferred method is a leak down test. 10% or lower is ideal. If a problem is indicated it can be easier to diagnose & a better idea of engine wear. Cutting the oil filter open & looking for any metal debris also is helpful in spotting lower end problems.
My preferred method is a leak down test. 10% or lower is ideal. If a problem is indicated it can be easier to diagnose & a better idea of engine wear. Cutting the oil filter open & looking for any metal debris also is helpful in spotting lower end problems.
