what should compression be on a 3.0L?

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indy440

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I tested mine and got between 180-185 on all four.

I looked through my manuals and couldn't find the spec. Its a 1993 3.0L with about 87 hours.
 
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stonyloam

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Re: what should compression be on a 3.0L?

indy440 said:
I tested mine and got between 180-185 on all four.
Click to expand...

Compression testing is kind of like taking blood pressure, different instruments, and different operators can give different results. It is more important that you get consistent readings across all 4 cylinders that some specific reading. A difference of only 5 psi sounds fine.
 
Don S

Don S

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Re: what should compression be on a 3.0L?

Did you run it at all before you did the compression test? If not, how long was it setting, and have you put any oil in the cylinders.
Seems high for a 3.0L.
 
J

Jessfly1

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Re: what should compression be on a 3.0L?

I got 145-150 on cylinders 1 and 4 but only 40-45 on 2 and 3. going to pull the head soon. This is a '91 3.0 OMC.
 
fat fanny

fat fanny

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Re: what should compression be on a 3.0L?

I believe the factory spes are 150psi it's in the stickies just look in the service techs specs thanx again Don
 
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indy440

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Re: what should compression be on a 3.0L?

I ran it on the hose for probably 20 minutes before the test. I revved it a few times before shutting it off. Then I immediately pulled the plugs and did the test.
 
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John_S

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Re: what should compression be on a 3.0L?

It sounds like it is a bit high unless the gauge is off. Do you have someone elses gauge to try? Only thing I've heard that would cause a high reading, is allot of carbon build up. Normally, not an issue on 4 strokes. Were the plugs black? How has you engine oil consumption been? I use seafoam sprayed into carb, to get rid of it on my 2 strokes.
 
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indy440

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Re: what should compression be on a 3.0L?

I'll have to try another gauge. Its a cheap one from the auto parts store and its like 10 years old.

It doesnt use any oil. Plugs looked perfect.
 
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