1975 Evinrude 50hp flywheel very difficult to turn

Hey guys,

I'm new to the forums, so I apologise if I'm posting in the wrong section.
I've got a 50hp Evinrude with electric start. I had it running yesterday, and it was turning very easily and starting up without an issue. I left it overnight, and went to the lake this morning. I tried to get it started this morning on the lake, and the starter was engaging into the flywheel, but it would only turn it a small amount before stopping. If starting the ignition again, it would do the exact same thing. The battery is fully charged.
Upon further investigation, I couldn't turn the flywheel by hand any more, it's too stiff to do.

Any suggestions on what it could be considering it was running perfectly yesterday?

Thanks,

Unfortunately it sounds like it has seized.

Suggest you search for remedies, I've never had to deal with one in that state.

First make sure the motor is out of gear. It should have a system that prohibits starting when it's in gear but stranger things have happened. Next, remove both spark plugs and attempt to turn it by hand. If it now turns easily then being in gear was your problem. If it's still hard to turn, then as nick suggested you may have a seized motor.

I've got an update, I sprayed WD40 all over the base of the flywheel, and left it for a few hours, and its started turning the flywheel over much more than it did before. I get an almost full rotation out of the flywheel, and the prop moves when it turns. Still very stiff though.
I'll try removing the plugs tomorrow, and keeping it in neutral. There's no system there to prevent it starting in gear.
I've seen some remedies of people filling their cylinders with penetrating oil. Do you think this would work?
As the prop moves, it doesn't sound like a seized engine, it could be something clogging it. I've recharged the battery, and give it another go.

I wasn't under the impression a motor could seize if used the day before. Maybe I'm wrong.

Any further thoughts?

With the plugs out of the motor it should turn over freely. If it does have your battery load tested and check all your connections.

I've taken the plugs out, and it was spinning freely. I gave it a few rotations by hand, and put the plugs back in, and the started is able to turn it over now (I can move it by hand quite easily now also). When in neutral, there's no problem, but when I put it in gear, it goes back to being quite stiff (much better than it was, but still not great).
Should I give it a few turns in gear to try to free it up?

Have you checked the lower unit oil ??