'75 merc slips, sort of, out of gear

[biggogg]

'75 merc slips, sort of, out of gear

I have '75 mercruiser that all of a sudden slowed to trolling speed but kept up the 3000 rpms I was driving at. When I eased off on the throttle, it sounded normal. However, when I tried to acclerate, there was no increase in speed, just a higher revving motor. It can move in and out of gear but cannot accelerate. Any thoughts?

 

[Trent]

Re: '75 merc slips, sort of, out of gear

Re: '75 merc slips, sort of, out of gear

First thing I would check would be two things. Make a mark across the hub of the prop and go try it. If the marks move its a spun prop hub. Second thing is to check the coupler. Its on the back of the engine where the outdrive attaches to the engine. Look back their and see if you see "rubber dust". Also did you notice if the temp went up when your problem started? If so it the coupler. To replace the coupler your going to have to pull the engine.

 

[biggogg]

Re: '75 merc slips, sort of, out of gear

Re: '75 merc slips, sort of, out of gear

Thanks for the starting point. I did not notice a temp increase, but maybe I am just being optimistic. Assuming it is the hub, is it simpler to replace the entire prop, or is this considerably more expensive?

 

[Trent]

Re: '75 merc slips, sort of, out of gear

Re: '75 merc slips, sort of, out of gear

Rehub is about half what a new prop is. 50-60 bucks.

 

[biggogg]

Re: '75 merc slips, sort of, out of gear

Re: '75 merc slips, sort of, out of gear

Thanks For your advice. I removed the prop and found bits of burnt rubber all around the hub. It has been sent off for repair. Appreciate the help.