compression question
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compression question
I just did a compression check on my 300 with 141,000 miles and got a range from 117 lbs to 165 lbs. Two cylinders were at the high end, two at the low, and two in between. Can some of you with experience tell me how these numbers sound?
Thanks,
Meck
Thanks,
Meck
Hotshot
Joined: Oct 2002
Posts: 18,488
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From: The Big, Oregon
compression question
All the cyl's should be within 85% of each other. If the two low cyl's are #'s 3&4, I would suspect a blown head gasket, otherwise, if it's not giving you a problem, keep running it. It'll run down to about 90psi.
Jared
Jared
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compression question
Thanks for your answer. The engine runs great, and the two low cylinders are #1 and #4, so I'll just keep trucking. I'm having no problems, just checked compression out of curiousity, then didn't know what I had learned once I had the numbers.
Meck
Meck
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Joined: Dec 2001
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compression question
I guess the motor will run out balance if the compresion varies too widely. For comparison, my 88 with 204,000 miles has 125lb in #1 and 150ish in all of the others. Motor is running good. I replaced my head gasket about 5 yrs ago. Kept having to add water to the radiator. I didn't get it milled or even try to ensure that it was straight, just put the new gasket on. I've heard these motors do need a new gasket sooner later because its such a long head.
I've done some overhead cam head gaskets and for me, I'd sure rather work on one of the 300 I-6.
I've done some overhead cam head gaskets and for me, I'd sure rather work on one of the 300 I-6.
