How to unfreeze a 90 Hp Mariner outboard

During the spark check and starter motor rebuild, the engine got frozen, not by weather.
It was not a hot freeze, like engine was running. Please give me suggestions of how to
unfreeze, short of tearing the motor apart.

It sounds like water may have gotten into the engine.-----------------NOW THIS IS TROUBLE , BIG TIME.------------------The bearings are damaged very quickly by corrosion.----------You need to act right away to loosen it up ( big socket and bar on the flywheel nut )and try to turn it. Then you need to find the scource of the water getting into the engine.-----------------Also check the lower unit to see if it is full of water and seizing up on you.-----------There is no time to think about this , you need to act now.----3 cylinder or 6 cylinder motor ???

ThanKs Mr racerone: It's a In-line 6. I didn't mention that my year/model has a reputation of being "dry", and it's
always slow to start -- like after 20 or 30 cranks, and rest. During the spark check, I cut off the gas thinking to
prevent accidental firing, that could have been the cause of freeze up. I have soaked the piston, trying what you
just described. I'll keep you posted.

This motor does not have a reputation of being " dry " and slow to start.Not sure where you get the idea that the motor will be " dry " after a bit of cranking with no fuel.That is simply not true !!-If one of these motors is " slow to start " it is because something is wrong with it.--------I still think there is water in the engine or the lower unit.--------------Time to check it and fix it. --------If there is water in the motor , i can assure you that the longer you wait the more it is going to cost.

A Junk boat yard guy told me that. Actually he the owner of the poor man's boat yard. Pretty knowledgeable guy. Is the space "under" the pistons, where the cranks and bearings reside open or enclosed? Sealed in oil? How could
water gets into it? The motor has not been in the water or rained on while spark plugs were out.

If water leaks into a cylinder via a leak on the exhaust plate gaskets it can drain onto the bearings.----------Perhaps you have a problem in the lower unit.--------------------The space below the pistons is not " sealed in oil "

HOLD YOUR HORSES BUBBA!!! How about a logical approach to find out why, or even if, the motor is actually frozen? There is simply not enough information given here to tell you to put a breaker bar and a helper pipe on the flywheel nut and invite your NFL neighbor over to help "unfreeze" your engine. What do you mean it "Got Frozen"????? Engines dont just freeze up, something has to cause it, like running with no oil, overheating, or leaving the cylinders open to the weather. If you really want help, give us all the facts.