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Old 10-07-2004, 11:47 PM   #1
nytoy
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Exclamation Uneven compression results '00 EJ25

How bad is this, obviously the compression is within spec, this is cold.

160
145
150
160

According to the service manual 130-160 is good, it shouldn't be more than 7 psi difference in the cyl's. Is this a sign of impending headgasket failure? This is for a car I'm looking to buy. Thanks.
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Old 10-08-2004, 12:03 AM   #2
Akarui
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check your valve train I had similar numbers on MY02RS and it was a sticky intake valve. I suggest a good cleaning with something such as SeaFoam cleaner then check it agian and see if it cleans the carbon buildup off the valves. It woudl help if you knew which valuse goes with which cylinder ie. 1-4.
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Old 10-08-2004, 09:35 AM   #3
nytoy
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Quote:
Originally Posted by Akarui
check your valve train I had similar numbers on MY02RS and it was a sticky intake valve. I suggest a good cleaning with something such as SeaFoam cleaner then check it agian and see if it cleans the carbon buildup off the valves. It woudl help if you knew which valuse goes with which cylinder ie. 1-4.

Hmm so I guess I shouldn't totally panic.
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Old 10-08-2004, 12:12 PM   #4
ratt_finkel
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Yeah, thats not a huge difference. I wouldn't worry about it.

Now, if one were at 120, or lower, then you should start to take notice.
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Old 10-08-2004, 12:20 PM   #5
jeffg
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motors are never even on compression, even when new. The general idea is +/- 10%. You are pushing the limites from 160->145, but I think you are okay. You should generally do compression tests with the motor full warmed up, but on an Impreza you would just end up with burned hands.

J
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Old 10-08-2004, 03:51 PM   #6
jamesfacts
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Doesn't look that bad. Subaru compression is inherently lower due to the flat engine design.
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Old 10-08-2004, 04:03 PM   #7
Hayes
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Was the compression measured with the throttle WIDE open. If not the the reading are bogus. If after measuring the compression do a vacume check with a good gage as this will help diagnoise a problem. ed
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Old 10-08-2004, 05:45 PM   #8
Akarui
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There's no reason to panic yet are you experiencing a missfire? If then engine runs good I would say give it both some injector cleaner and some seafoam thru the pcv to clean off your intake valves and you should be good.
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Old 10-13-2004, 02:40 PM   #9
HndaTch627
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cold compression test=uselss

warm it up and try again and make sure the thottle body is Wide open when cranking
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Old 10-13-2004, 03:12 PM   #10
nytoy
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thanks for the responses, I'm gonna try some super fuel injection cleaner, then warm it up and try it again.
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