Broken axel??

[Basios]

Suddenly my old Suzuki 7.5 outboard lost connection to the propeller, so I had to row home. The engine revved up, and the propeller no longer turned. When I came home I could see that the axel down to the gearbox unit with the propeller did not rotate, when the engine was on, even though the gears (forwards and backwards) where engaged. The strange thing is that when I rotate the propeller manually there seems to be nothing wrong with the connection to the engine - axel rotates, pistons move etc.
Can anyone help?

[gaffer45]

axel

Did you spin the hub of the prop? I did that with a larger engine, under a load the prop didn't spin, when out of the water it would. The rubber piece between the spline and the housing of the prop will lose traction with age. Just a thought.

[Basios]

It was a broken crankshaft

Thanks for the reply. Amazingly the problem seems to be that the crankshaft broke. The top piston can be activated by turning the magneto, with the bottom piston not moving, and the bottom piston can be activated by turning the propeller with out the top piston moving. Strangely enough the engine still starts easily, with no strange noises, but it must be running on the top cylinder only - and with out connection to the lower cylinder and piston or the propeller - sounds pretty crazy, but this this seems to be the case. Why the crankshaft broke in the first place I donīt know. It was an old used engine that I was trying out, and luckily did not pay to much for. I just couldn't figure out what was wrong, and thought that I would check on the spark plugs for nothing better to do - and then discovered that the two piston could be moved independently...No big loss -
Kind regards.

[kmoose]

Sounds as if it is a modular crankshaft. It may have just sheared the bolts holding it together. Might be fixable??

[Basios]

Modular crankshaft...

Thanks for the thought - seems like an idea - also because of the lack of strange noises - I will have to check up on that - If anyone knows of modular crankshafts used for 7.5 Suzuki outboard engines, 2 stroke, 2 cyl., maybe 15 - 25 years old, I would be gratefull to hear about it. Kind regards.