Compression test results
01-02-2012, 01:47 PM
#1
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Year: 1993
Model: Cherokee
Engine: 4.0
Compression test results
My Jeep has never seemed to have the power that my friends 4.0L jeeps do. Did a compression test today for the hell of it, this is what i found.
Im not sure what it "should" be, so my question I guess would be How does it look?
Im not sure what it "should" be, so my question I guess would be How does it look?
01-02-2012, 02:41 PM
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Year: 1998
Model: Cherokee
Engine: 4.0L HO
The only thing significant about those numbers is cyl #5......it's headed south. The range/variance of the numbers hi/low should be less than 10%.
01-02-2012, 02:48 PM
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Year: 1998
Model: Cherokee
Engine: 4.0L HO
Correct way to do a compression test is with the motor warm, all spark plugs removed and throttle held wide open while starter motor is cranked.
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01-02-2012, 08:46 PM
#9
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Year: Several
Model: Cherokee
Engine: 4.0
And - make sure each cylinder gets an equal number of pulses.
Watch while it pulses - at least 90% of the final value should happen with the first pulse.
95-96% on the second pulse.
Max pulses should be 4.
Some people crank and crank till they get what they want - totally invalid!
Watch while it pulses - at least 90% of the final value should happen with the first pulse.
95-96% on the second pulse.
Max pulses should be 4.
Some people crank and crank till they get what they want - totally invalid!
01-02-2012, 09:00 PM
#10
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Year: 1998
Model: Cherokee
Engine: 4.0L HO
And - make sure each cylinder gets an equal number of pulses.
Watch while it pulses - at least 90% of the final value should happen with the first pulse.
95-96% on the second pulse.
Max pulses should be 4.
Some people crank and crank till they get what they want - totally invalid!
Watch while it pulses - at least 90% of the final value should happen with the first pulse.
95-96% on the second pulse.
Max pulses should be 4.
Some people crank and crank till they get what they want - totally invalid!
01-02-2012, 09:24 PM
#11
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Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
I like 7. Just seems thorough. X2, warm, leak-down, 10%. What year? Is yours really doggen or are they just louder? If you are sure everything is right and it's doggen, once I had a clogged cat do that. Finally I loosened the bolts on the header pipe on (her "K" car), and WOW, night and day, that was it.
01-02-2012, 09:48 PM
#12
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Year: 1998
Model: Cherokee
Engine: 4.0L HO
I'm still puzzled about 140 psi on all six......seems physically impossible.
Leak down and compression test are 2 different animals.
Leak down and compression test are 2 different animals.
01-02-2012, 10:44 PM
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Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Well...just googled it, I stand corrected. Done with compressed air.....
Last edited by DFlintstone; 01-02-2012 at 10:48 PM.
01-03-2012, 12:17 AM
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Year: 1997
Model: Cherokee
Engine: 4.0 Liter
What should the ideal or target compression numbers be for a 97 4.0?
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Flash
Last edited by Flash1034; 01-03-2012 at 12:23 AM.