compression done today

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Oct 20, 2012 | 05:19 PM

nightowl10

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compression done today

Hi all,

Had a compression test done today, and here are some numbers.

Have a 1988 Ford Ranger pickup, 2.0 litre , 4 cylinder engine, 5 speed maual

All 3 cylinders were 140 psi, and one was 110 psi. So I would suspect that rings in this 1 cylinder is gone. Why would not all 4 cylinders wear the same? The truck now has about 130k on speedometer, which is about only about 82 thousand miles. Its weird

Thanks

Oct 20, 2012 | 06:44 PM

19704X4F250

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From: Butler, IN

Most mechanics want compression readings to be within 15 pounds of each cylinder. Cylinder #1 is on the low side but no they are not gone.

Oct 20, 2012 | 07:02 PM

merace19

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You have a lot of factors on why the rings dont wear even. Metal in block is not all that great, so can and will have harder spots and thicker spots, Same for rings. Also the way the fuel system feeds each cylinder. One could be working harder than other.
Then we get into valves and if there is crud on back side of them. how much has the cam worn and lifting that valve.... Engines are complicated.

Oct 20, 2012 | 09:26 PM

wtroger

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I wouldn't trust one test. Removing the plugs can cause some carbon to be dislodged and get under the valves Squirt a little oil in all cylinders and see what the numbers are If number one comes up to match the others then yes the rings are a bit bad. If it doesn't come up it is a valve issue.

Oct 21, 2012 | 06:12 PM

nightowl10

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Thanks for all the great advice! Have to make a correction here. Starting at the front of the engine is no 1 - 140psi, 2=140psi, 3-110psi, and 4 - 130psi