50hp Merc Problem

[Walleye5150]

Engine Runs good but when I put it in gear and give it gas it only goes like 3 mph. Engine rpm goes up but the boat don't go. I thought maybe my propeller was slipping. It does go in forward and reverse gears fine just won't go. I just bought the boat and had it out once maybe it's the wrong size of prop for the engine. I don't know much about boat engines.

 

[Windykid]

Re: 50hp Merc Problem

Mark your prop and hub. Run it and see if it is slipped. You may just need a new prop. Did it come with a spare? What size is it?

 

[Silvertip]

Re: 50hp Merc Problem

You very likely have what's called a "spun hub" on the prop. The center part of the prop (where the nut is) is called the hub. There is a rubber cushion between the hub and outer part of the hub to absorb shock should the prop strick a rock, stump or some other debris. In some cases that bond between the rubber cushion, the hub and the prop itself breaks so the hub simply spins inside the prop. This can be checked as described. Place a mark on the hub of the prop and another mark directly in line with it on the outer part of the prop. run the boat until the problem occurs. Check the marks. If they are no longer in line the hub has spun.

 

[Windykid]

Re: 50hp Merc Problem

Thanks Silvertip, I guess I should have explained it better to walleye.:redface:

 

[Walleye5150]

Re: 50hp Merc Problem

The prop said 12p thats all I could find on it. If it does have a spun hub is that and easy fix. Thankyou

 

[Silvertip]

Re: 50hp Merc Problem

12 stands for 12 inches of pitch. Fairly standard for that motor. You cannot fix a spun hub yourself. A prop shop can do it. Prices vary but it is generally much less than a new prop which is the only other alternative.