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Old 02-08-2009, 08:56 PM   #1
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Default Compression test results

Do these results look fine, or like there may be some sort of problem?
1-65-55
2-75-80
3-50-65
4-75-80
5-55-65
6-45-55
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Old 02-08-2009, 09:33 PM   #2
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that is very low, does it even run? they should be around 150 psi. try it now with a wet test. squirt a couple shots of oil in the spark plug hole right before you test a cylinder. if it goes up more than 10-15 psi, then the rings are shot. make sure you have an o ring on the end of the tester and the gauge is reliable to.
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Old 02-08-2009, 09:37 PM   #3
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Its not in psi. I'll go check how its being measured. Runs fine. Rebuilt a while back. Idles a bit low, but I cleaned the IAT I think its called, and I think that fixed it. Can't get it to start atm for whatever reason.
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Old 02-08-2009, 10:05 PM   #4
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the numbers should be within 15% of eachother
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Old 02-08-2009, 10:07 PM   #5
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Quote:
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the numbers should be within 15% of eachother
yep, a hi of 80 and a low of 45 is also not good.
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Old 02-08-2009, 10:10 PM   #6
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nevermind psi it is
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Old 02-08-2009, 10:12 PM   #7
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that engine is hereby

beat

out of curiosity how many miles on it?
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Old 02-08-2009, 10:13 PM   #8
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Quote:
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yep, a hi of 80 and a low of 45 is also not good.
What do you think could be possible problems? Your tests are reading around 150?
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Old 02-08-2009, 10:13 PM   #9
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I compression tested mine when I first bought it. It had 185K and the average among all the cylinders was 170.
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Old 02-08-2009, 10:14 PM   #10
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do the wet test as i described above, that will tell you if its rings, to have all cylinders that low is probably rings, or bad tester. does it run? it really shouldn't with those numbers.
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Old 02-08-2009, 10:17 PM   #11
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ha maybe I'm not doing it correctly? 230000 miles, replaced cam, crank, 2 pistons, all rings and bearings, oil pump, water pump, starter, and radiator in last 2 months. It has been driven frequently since then, I've just been trying to figure out why it has been idling so low. IAT I'm pretty sure. I don't think my engine is dead.
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Old 02-08-2009, 10:21 PM   #12
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do you mean iac, iat is intake air temp, iac is idle air control. but cleaning the throttle body is important on jeeps.

your tester may be bad, or the o ring on the end that goes in the head goes bad leaking pressure showing low readings some times.

but if they are that low i'd be worried, is your battery strong when you test, and are you letting it crank 4-5 times?
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Old 02-08-2009, 10:24 PM   #13
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3-4 times... not sure which one. It was on the intake manifold, right behind the TB. It was covered with crap.
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Old 12-16-2009, 06:41 PM   #14
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Quote:
Originally Posted by mycherokee1989 View Post
ha maybe I'm not doing it correctly? 230000 miles, replaced cam, crank, 2 pistons, all rings and bearings, oil pump, water pump, starter, and radiator in last 2 months. It has been driven frequently since then, I've just been trying to figure out why it has been idling so low. IAT I'm pretty sure. I don't think my engine is dead.
my 93 xj idles at 200-300 rpms.. I did a compression test a couple days ago and most of my cylinders were at 100psi..cyl#1 was at 50!!!! so now i know that is my problem and i can stop changing parts.. thats your problem with low idle if your readings are correct...
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