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I just ran a compression test on my 96 Sentra with 120k miles. All of my readings were between 145 and 155 pounds for all four cylinders. All tests were done after I put a squirt of oil into the spark plug hole. The increase in each cylinder after the squirt of oil was approximately 10# per cylinder. I read in service manual that I should be getting a min of 171 pounds and a max of 199 pounds. Whew! These numbers are very high and I am way out of the ballpark. The car runs great. So.... how close am I to an overhaul?
 

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in^3,N20,RPM,PSI
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you may be down on power a bit and have a little worse gas mileage but you should be ok driving it...

the compression test results can be thrown off if your battery isn't at full charge so it might be a little low due to that. as long as they're about the same across the board you should be able to drive it ok though.
 

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you may have done this but, make sure your engine is nice and hot when you perfom the compression test. be careful since the sparkplugs are nice toasty
-dave


alkon said:
I just ran a compression test on my 96 Sentra with 120k miles. All of my readings were between 145 and 155 pounds for all four cylinders. All tests were done after I put a squirt of oil into the spark plug hole. The increase in each cylinder after the squirt of oil was approximately 10# per cylinder. I read in service manual that I should be getting a min of 171 pounds and a max of 199 pounds. Whew! These numbers are very high and I am way out of the ballpark. The car runs great. So.... how close am I to an overhaul?
 

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Did you hold the throttle wide open when you checked the compression? If not, the readings are low because a vacuum is created in the intake plenum and it doesn't compress a full charge of air.

Lew
 
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