HELP!!! Trouble in compression difference

[kapaafire]

posted earlier about my motor overheating. Changed the thermostats, deflectors, head gaskets, and water cover gaskets.
Checked compression today:
I got 118,120, 95, and 80 (uggh).

When changing the head gaskets, I noticed that the cylinder w/ 80 psi. had some scoring inside.

What to do?

Would I need to hone the cylinder?
Is it worth it?

Also noticed that there was no spark on that coil. Could a coil fry from the overheating?

Also the other coils had a spark, but not very strong.
Change plugs?

Thanks in advance.

Troubled in Hawaii

 

[kapaafire]

Re: HELP!!! Trouble in compression difference

Actually checked the scored cylinders compression again and I got 90 psi.

 

[emdsapmgr]

Re: HELP!!! Trouble in compression difference

Running the engine in it's present condition is not the answer. Right now, you know you need a new piston and ring set for sure. Time to tear it down and check the cylinder walls. If they are oversize, tapered or grooved, an overbore is in order. Was there any pitting on the (80#) head or piston crown? I would take a close look at the piston in the hole with 95# of compression also.

 

[kenmyfam]

Re: HELP!!! Trouble in compression difference

Description says re-bore to me if you want good reliable use from the motor long term.

 

[kapaafire]

Re: HELP!!! Trouble in compression difference

Re-checked the compression again and I had 120, 120, 110, and 90.

The 2 lowest values where on the port side of the engine. With the low value on the bottom cylinder.

I noticed that this cylinder had slight grooving when I changed the head gaskets, turns out it is the one w/ the low compression value.

I only have experience w/ the tasks mentioned in the first post (thermos, gaskets, etc.). How difficult would it be to break down the engine to get it re-honed by a machine shop?

What kind of problems would occur if I ran the motor with this kind of difference?

It's an '83 115 hp evinrude.

Thanks again

 

[R.Johnson]

Re: HELP!!! Trouble in compression difference

If the cylinder wall on the low cylinder look's bad, the piston will look twice as bad when you take it out.

 

[kapaafire]

Re: HELP!!! Trouble in compression difference

would it be safe to run motor at that compression diff.?

Also noticed that my water cover gasket is still leaking after I changed it. Used OMC gasket sealer, torqued bolts....don't know why still leaks.

 

[kenmyfam]

Re: HELP!!! Trouble in compression difference

Water cover may be warped. Check the mating surfaces, or has a crack in it and that is what is leaking. Personally I would get the compression thing taken care of. Any scoring of the walls or rings or pistons will only get worse.

 

[mikesea]

Re: HELP!!! Trouble in compression difference

are you torquing the bolts down,if so,are you sure the threads are clean.Often those threads in the block can get salt or corrosion build up,sometimes when these threads arent chased and cleaned you get a false feel of tight.They do strip easily too.That said,are you seeing the water flow on the outside of the block,or are you getting water in the engine.Often the 4 cyl.omc get cracks in the exhast are where water passages pass,the lightest weep can devolop,very hard to find,if that happens you need it welded