Outboard trouble ?

[outdoorsman37]

Hello. I have an 18 HP Evinrude Fastwin 1968. I just bought it and when I rev it high in gear it stops going. it keeps reving higher but no speed. Could this be the gear slipping out? the propeller? the gears/clutch dog? or movement of the trim/tilt?

I first thought it was the gear handle because it was broken off but I replaced it and I held it down to try to make sure it didn't slip out of gear. It didn't seem like it slipped out of gear when it happens.

It didn't have a trim bar to hold it steady so my next hope was that it moved slightly and that changed its ability to move the boat. it does seem to move slightly when it happens. Really a small amount. I bought a bar and will try it with the bar and motor secured but I don't think that is what is causing the problem.

I just pulled the propeller off. There is nothing stuck in the area. When I put the propeller back on though I noticed that I could turn the propeller with a significant force with the shaft not turning. That didn't seem normal so I need to know if this is normal? I have to put a signficant force to it to turn. Is this the problem?

The only other thing I could think it could be would be the gears themselves either slipping or worn or the slave dog thing or where the powerhead connects to the gear shaft? That would be worst I think because I would have to tear the lower end apart. But I will if that is the problem.

Also... There is a lot of play in the shaft when it is in gear. I would say maybe an inch or more. Is this normal? I think I can even move it with force. I didn't check if it was turning the flywheel though.

Please, if you have any experience with this can you reply to this post? I can't afford to take it in to get it repaired.

Thanks!

 

[dwco5051]

Re: Outboard trouble ?

I had one of these years ago but can't remember too much about the exact prop to shaft connections. Since the prop turns and the shaft doesn't you have narrowed your problem down to its location. Check shear pin is engaged right, nut not cross threaded, etc. Blow up a parts diagram for this motor and look at the parts between prop and shaft and compare to yours. You will probably be able to figure out from there what is wrong.

 

[outdoorsman37]

Re: Outboard trouble ?

Thanks! It is not the sheer pin. The prop is fixed with a pin below it. The sheer pin just holds it down onto the pin beneath. What turns is part of the prop itself. There is a cylinder in the middle of the prop and that stays put but the outer prop turns around it when enough force is applied. so all the turning happens on the prop piece itself. Make sense? Thanks!

 

[dwco5051]

Re: Outboard trouble ?

Mine must have been an earlier model. Different prop set up. You have the classic symptoms of what is known as a spun hub. If you can turn it by hand with some force imagine what force 18 hp exerts on it. New prop or prop repair is needed.

 

[outdoorsman37]

Re: Outboard trouble ?

I hope you are right. I am going to put a new prop on. Thanks for the info!

 

[samo_ott]

Re: Outboard trouble ?

Yes, you describe the classic spun prop case. Yours is bad though, usually you cannot spin it by hand. The props can be fixed at a prop shop (call the OMC dealer for a quote) or just replace with a used prop.

I love the 18's and have many of them. I use one almost daily in the summer