Low compression 25-30 lbs Seafom?

[glennbobg]

Hello,

I have an '89 85 hp wth really low compression 25-35 lbs on all three. The head was half off when I got it so I replaced the gasket. Cylinder walls looked great crosshatch still evident and no ridge at all. Could this be a candidate for seafoam or is it time to do the rings?

 

[Bigprairie1]

Re: Low compression 25-30 lbs Seafom?

Something doesn't sound right here. 25-35 lbs consistently on all cylinders?
I've never heard of all cylinders being down low like that. Are you sure you're gauge is seating and sealing completely when you are doing your checking? Try another gauge if you can borrow/find one.
BP

 

[Frank Acampora]

Re: Low compression 25-30 lbs Seafom?

Obviously, there was a problem when the previous owner sold it to you! That's why the head was removed and partially re-attached.

Certainly, at this point, seafoam is an inexpensive and the easiest remedy. It could not hurt to try it, but I doubt it will do much good.

After treatment, if compression has not returned to at least 100 PSI, pull off the bypass covers and the exhaust cover, turn the flywheel by hand, and look at the rings. I'll bet that all three cylinders have either broken rings or aluminum wipe-off keeping the rings compressed away from the cylinder walls. If either is the problem, seafoam will do no good. Be aware though, that the hot spots of the cylinders are top and bottom. It is possible to have aluminum wipe-off and not see it with the pistons in the cylinders.

Unfortunately, I think that engine is a candidate for rebuild even though the cylinders look good.

If you see no evidence of the problem causing the low compression. remove the carbs and manifold. Then through the reed opening, remove the rod cap from one piston. Push out the piston and look at its condition.

Fortunately, three pistons and ring sets are not that expensive and can be replaced without removing and disassembling the block.