please help new to marine engines

[hindsey123]

ok guys i am new to marine engines but do all my own work on my cars/motorcycle so i feel that with some guidance i can do the boat motor i have a 1973 24 foot pontoon boat with a 120hp OMC sterndrive the motor was sitting for 2-3 years before i got the boat and the previous owner said when he put it up it was running but now it seems to be seized i took all four plugs out and put some marvel mystery oil in them to see if that would allow them to be freed up while my father was bumping the key switch to turn the boat over i put a big pipe wrench on the ball gear that is on the back of the motor (the out-prop is off the boat) but had no luck at all so now i am trying to take the belt housing around the flywheel off to get into there and see if that's where my problem is or what it could be but i can not get the housing to split? im not sure if i have to take the ball gear off first but from what i can gather from diagrams on the internet it doesn't look like i need to please any help will be greatly appreciated.

 

[Master mechanic]

Welcome aboard !

You want to unfreeze the engine correct ?

Put the spark plugs back in take the battery out of the boat.

Fill the engine to the top with kero or diesel fuel, close it up and wait 3-4 day's.

You want to remove the engine from the bay ?

Remove all the wires and cables.

Remove the front engine mount top nut.

Remove the flywheel cover screws 5 if i remember correctly.

Remove the 2 bolts and 5 screws that hold the bell housing to the engine.

Make sure you get all the screws and blots out. The one bolt starboard side that acts as the main ground from the battery.

The other thru bolt is on the port side see where the 2 tilt solenoids ground is.

Now the engine can move forward 6 inch's.

First support the drive, i put a piece of flat wood under the skeg and crank the trailer bow up till it touch's the skeg. Of course the drive is fully down.

Get creative if the boat is not on a trailer a floor jack will do. The point being the drive will move downward and jam the shaft and the engine won't come away from the bell housing.

Be smart, be safe keep the boat away from your house i ain't your babysitter diesel and kero ain't toy's.

Post back.

 

[hystat]

I had some luck once with a seized coupler by taking the ball gear seal retainer bolts out and using two big heel bars under the ball gear, and pulled the intermediate shaft rearwards out of the coupler with leverage that way. Like anything, smooth consistent force will win over hammering any day.
Also slim chance, but possible the intermediate bearings are actually what is seized.

I don't know if an old rear main seal or cork oil pan gasket etc. would like diesel fuel too much, no fear of them all swelling up chief? Away from the house? I have 900 liters of kerosene/diesel in my basement - we still burn oil for heat up here. I mean money.... no nat gas here.