Re: Frozen Johnson 3 hp 1960
There are three spots the motor can freeze at (or any combination of the three).
Most common is the pistons are stuck. Can be caused when the motor is inverted shortly after running, allowing water into the cylinders. Piston rings rust to the cylinder walls. Can also be caused if the motor has had a catastrophic failure - lack of oil, overheating, etc.
Second most common is water ingestion into the crankcase, rusting the crankshaft. Can be caused by water in the gas, submersion, etc. Can also be caused by catastrophic failure - lack of oil in gas, etc.
Third most common is water in the lower unit, rusting the gears and shafts.
I'd start by pulling the lower unit to easily dismiss that as a possibility. Then pull the cylinder head to take a look there. DO NOT attempt to free the motor with torque on the flywheel. That motor has aluminum rods and they WILL bend/break with excessive force. If the powerhead is stuck, pull it apart to find where. Don't try to "free it up". Even if you do get it unstuck with penetrating oil or the like, there's a good chance some bearing surfaces are now rough due to rust and will wear prematurely. Your motor has "plain bearings" which can't take a whole lot of abuse. If the rust is localized and not deep in the surfaces, you might be able to polish them out with emory cloth.