95 mercruiser alpha 1 outdrive problem

Hello i just signed up on this site, i have a 95 maxum with a 4.3/alpha one outdrive on it. yesterday i was out on the lake and had the boat fully trimmed out doing about 52 mph when the motor reved and the boat slowed. i shut it off turned it back on tried putting it back in gear and going but the boat barely moves and the engine just reves up. the prop is spinning it just isn't moving the boat but maybe 2mph. it basically seems like a auto transmission in a car thats low on fluid and barely moves but the engine revs high.This is my 4th boat however my last 3 were all jet boats and i have no clue how these i/o drives work also how to work on them. i was gonna just buy a manual and try to fix it myself does anyone know what might be going on with my boat? thanks for the help!!

Re: 95 mercruiser alpha 1 outdrive problem

Most probable cause is a spun hub in your prop. The rubber breaks loose from the inside of the prop hub.
Could also be a spun coupler hub, same setup as a prop, but since you had no mention of the smell of burned rubber, I would bet on spun prop hub.
Put a mark on the inner and outer portions of the hub, put it back in the water and give it some power and see if the lines move.

Re: 95 mercruiser alpha 1 outdrive problem

I hope that is the problem and not something in the drive, i just put that prop on there a couple weeks ago,it was refurbished so maybe that's what it is. i didn't smell any burning rubber or really hear any noises that weren't normal.do you think i could put some marks on it then hook the hose to it and power it up or will i need to take it to the lake and put a load on it in order to know for sure?

Re: 95 mercruiser alpha 1 outdrive problem

Do it in the water so you have some prop resistance. As Don mentioned could be the drive coupler also embeded in rubber. was the smell coming from the engine compartment? check it next time out. Mark prop and if you can get it to slip smell toward the back of the engine for the smell is the strongest.

Re: 95 mercruiser alpha 1 outdrive problem

I'm not sure what you mean by the drive coupler? it has a michigan prop with the hub built in. i actually just went out and looked at the prop and it looks like theres a little bit of melted rubber "i believe" between the prop hub and nut assembly so it may just be that. i didn't smell any rubber or anything else after it happened yesterday,i opened the engine compartment and everything,i just figured something in the outdrive broke but i was confused because i still seen the prop spinning and shooting water.

Re: 95 mercruiser alpha 1 outdrive problem

They will spin with no or light load but under power in the water they will spin on the rubber hub. There is nothing inside the drive that will do this without you knowing about by strange and costly noises.

The splined part of the prop is mounted in rubber and pressed into the outer part of the prop. At some point the rubber goes bad and will slip causing the engine to rev as the prop slips on the hub. If you see bits of melted rubber this is no doubt what your problem is.

There is a similar situation on the back of the engine where the drive shaft goes in. But usually when this goes you will smell the burning rubber because it is inside the boat. This is the engine coupler.

If you have a spare prop (and you should) try it and see if the problem goes away, after you try the hub marking that was explained.

Re: 95 mercruiser alpha 1 outdrive problem

Ok guys thanks for the help I'm gonna try it later and hopefully get it fixed. Appreciate the info