Chrysler 7hp


Old 05-29-03, 12:58 PM
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Join Date: Feb 2003
Posts: 153
Chrysler 7hp

Hey guys, I have an older (1960's?) Chrysler 7hp outboard and I am wondering what the compression should be on it? It measured out at 70psi on my that enough?

Thanks again!
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Old 05-29-03, 04:00 PM
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70 PSI sounds a little low. Should be a minimum of 100 PSI, even in an older engine like that.

Spray a goodly amount of Mercury Power Tune or other de-carboning product into the cylinder, turn it over by hand with the plug out and let it sit over night. Then pull it a few times to blow any remaining solution out. Test it again. Hopefully you would have freed up the rings, and will have restored compression.

If it's still low, put a few squirts of motor oil in the cylinder turn it over once or twice to spread the oil and re-test. If it's now significantly higher than it was, you'll need new rings, and maybe a hone job on the cylinder.
Old 05-31-03, 08:28 AM
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Join Date: Feb 2003
Posts: 153
Thanks...will give that a shot as soon as I get a chance and let you know how it pans out.

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