Compression Numbers
05-21-2016, 12:56 PM
#1
Senior Member
Thread Starter
Compression Numbers
96 grand 4.0 with 177 on the clock. just picked it up a couple days ago and am going through it. the compression numbers are inconsistent which bothers me. what do you guys think and can you tell me what the manufacture compression range is?
front to back:
135
145
155
142
130
145
front to back:
135
145
155
142
130
145
05-21-2016, 01:00 PM
#2
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Join Date: Mar 2012
Location: Racine, WI
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Year: 1997
Model: Cherokee
Engine: 4.0
Compression should be 120-150, and all cylinders should be within 30 of each other at worst but preferably all cylinders should differ from the best one by no more than 10%. Your numbers look just fine.
Last edited by mschi772; 05-21-2016 at 01:04 PM.
05-21-2016, 07:48 PM
#4
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Year: 1999
Model: Cherokee
Engine: 4.0
Those numbers are not a concern. Cylinders are close enough; it's not at all unusual to have the variation you have posted at your mileage.
Really evaluate though what might need to be done with your "new to you" 96. That would include transmission fluid, differential fluids, transfer case fluid, oil, air filter, coolant hoses (so often ignored and shouldn't be!), thermostat, tuneup hardware like plugs, wires, cap, rotor, etc.
Preventive maintenance is always the best strategy. It's pay me now or pay me a heck of a lot more later.
Enjoy your Jeep!
Really evaluate though what might need to be done with your "new to you" 96. That would include transmission fluid, differential fluids, transfer case fluid, oil, air filter, coolant hoses (so often ignored and shouldn't be!), thermostat, tuneup hardware like plugs, wires, cap, rotor, etc.
Preventive maintenance is always the best strategy. It's pay me now or pay me a heck of a lot more later.
Enjoy your Jeep!
Last edited by tjwalker; 05-21-2016 at 07:56 PM.
05-21-2016, 07:51 PM
#5
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Join Date: Aug 2011
Location: Nor-Cal Coast
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Year: 90,84
Model: Cherokee
Engine: 4.0,2.5
Agreed, you're fine 
Do be aware 96 is in the middle of changes. (some are different than both 95 (OBD-I) and 97, (OBD-II), but share things from both) I'm not sure what to watch for though. Both the fuel pump and the FSM, (Factory service Manual) come up.
OBD 1.5?
Do be aware 96 is in the middle of changes. (some are different than both 95 (OBD-I) and 97, (OBD-II), but share things from both) I'm not sure what to watch for though. Both the fuel pump and the FSM, (Factory service Manual) come up.
OBD 1.5?
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