Piston ring help 1987 3.0 L merc.

I'm rebuilding my 1987 3.0 L mercrusier because of smoke out of valve cover and found a blown head gasket and two pistons with stuck rings any ideas on getting rings off with out damaging pistons I have them soaking in PB blaster but still stuck will heat work or should I take them to a machine shop...Also the new rings came with no label I know the oil rings but which one is the compression ring and which one is the scrapper ring the only differece I see in the two rings is on is wider than the other and does the dot on the rings go up or down..older rings on pistons don't have the dot....

 

Rings should come identified. The dot may go either way depending on the manufacturer. It would be safer if you call them. If the rings are stuck with rust, you can pry them with an icepick and a hammer. Find the end of the ring and drive the pick and pry. Heat helps to expand the groove. If the piston dragged and you see deep scores, it may not be salvageable.

 

there are no scores I believe there just stuck because of sitting for a long time I got this motor in another boat that was cheaper than getting a new exhaust part for my Glastron sx-17

 

A light tap with a deadblow will usually free the rings, at which point you can examine the lands for damage.

 

Ideally a groove cleaner tool will get them right. Otherwise, use a broken old ring to scrape them clean.