Turning my 1975 Mercuiser 165 engine by hand?

[Bayliner 1975]

I just purchased a 1975 Bayliner with a Mercruiser 165 engine. I think the engine might be seized. I have read that you should be able to turn it by hand. I have ordered the service manuals but it will be days before they arrive - I don’t think it will have instructions on how to do it in the manual. Does anyone know how if it is possible to turn it by hand? If so could you please tell me how to do it? I have tried moving it with the belt with no luck. I do not want to do full rotations in case I damage the cylinder walls just want to see if it moves a little. If you reply with instructions - I have just purchased the boat and no very little about the engine. Thank you

 

[Scott Danforth]

just hot-wire the starter. if there is damage to the cylinders walls already from rust, it wont matter if you try to turn it over since the damage is already there.

or use a prybar on the ring gear teeth

or pull the damper and use a GM crank socket.

do not attempt to turn the motor over by the crank bolt, you will either strip out the end of the crank or snap the bolt

 

[GSPLures]

What I did for my motor was carefully inspect the engine. I then took the plugs out looked to see what I could inside of cylinders. I then put a little bit of MMO down each cylinder let soak for a day or 2 then bumped the starter.