1990 yj compression test results need help - JeepForum.com
 
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post #1 of 5 Old 12-13-2011, 07:54 PM Thread Starter
mangoman123
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1990 YJ Wrangler 
 
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1990 yj compression test results need help

OK today I did a compression test. My results were
Cylinders 1 2 5 160 Psi
Cylinders 3 4 6 150 psi
Is this good or bad? Should I have the ten pound difference between them?

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post #2 of 5 Old 12-13-2011, 07:56 PM Thread Starter
mangoman123
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Oh, its the 4.2l engine. Sorry
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post #3 of 5 Old 12-13-2011, 10:10 PM
ratmonkey
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Its perfect.
Anything under 120 psi is getting worn, around 120psi average with a 15psi spread you should figure out which end of the cylinder needs refreshed(head/valve job or rings)
One super low cylinder is usually a head gasket (if no racket from the valve train or a busted piston is expected)
under 100psi average the motor needs rebuilt in full
Under 80psi it probably wont run.

'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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post #4 of 5 Old 12-14-2011, 09:31 AM
oteps
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Yep those results are good. Are you having an engine problem or did you just want to check compression?
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post #5 of 5 Old 12-14-2011, 03:40 PM Thread Starter
mangoman123
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Weird feeling with power demand, like up hills, plus a knocking sound. This thing is killing me on new parts though.
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