Slipping Motor

[dave524]

Hello. I have a old old Mercury 7.5hp outboard that has a problem. When you give it throttle in forward gear it goes, and then it starts slipping and looses power, but the engine is racing. What do I look for ? I never had a outboard apart, but am very mechanically inclined. Also , I changed the lower unit oil before running it, and afterwards the oil is full of water.( Very Milky ) What causes this, and are these motors hard to work on. Serial Number is 4085932. Thaks !

 

[AMD Rules]

Re: Slipping Motor

Sounds like a spun prop hub. The rubber inside can lose its grip on the hub over time, or specifically if you hit a submerged object. What you end up with is a prop that is sitting still, while the prop shaft rotates inside.<br /><br />To verify it...mark a line on the center of the prop that extends out to the hub. After you return from a water test, if the marks don't line up anymore you have a slipping hub.<br /><br />To fix it, you can replace the prop or have it rebuilt at a local shop. Quite common, and not too expensive.

 

[AMD Rules]

Re: Slipping Motor

Oh...and the milkshake needs to be fixed. Do yourself a favor and get a factory service manual. You have a leaking seal somewhere in the lower unit. It may also be the gasket on the vent or drain screws. A few places to check.<br /><br />btw... thats a nice old motor...circa 1975.

 

[dave524]

Re: Slipping Motor

Thanks for the info, I will get a new prop, and a service manual. Thanks again !