1986 US Marine Force 50 outboard motor low power

[littleTommy]

Greetings - my apologies that this thread is so long.

I recently bought a used boat that had a 1986 US Marine Force 50 outboard motor attached. I took the boat out to test it on the water. The boat had no power during take off and would rev like it was coming out of gear if I put the throttle all the way down. I then eased into it and the boat slowly picked up speed to where it would get on plane and then rode fine from there. I came home and after reading more on this forum I decided that I may have a slipping propeller hub. I took my prop off and found not sign of slipping. While removing the prop I did notice that the exhaust did not come out of the prop like it does on most outboard I have seen. It comes out of an opening on the bottom of the motor. Long story short my exhaust diverter was missing from the motor and this is what was causing the motor to lack pushing power. The exhaust was pushing the water away from the prop causing conditions very similar to what people describe when they have a slipping prop. I fabricated a new diverter and then went for a test run. The boat got on plane immediately and accelerated like it should. The reason the boat would eventually get up to speed without the exhaust diverter is because as the boat speed increased it was pulling the exhaust away from the prop. In summary:

If your outboard does not have thru prop exhaust and the dirverter happens to be missing that will make your boat behave like the prop is slipping.

I hope this helps someone who buys a used boat with a similar motor design and is experiencing similar issues.

 

[emoney]

Re: 1986 US Marine Force 50 outboard motor low power

Good for you littleTommy and welcome to iboats. It's always nice to see someone post a thread sharing how they repaired an issue. Make yourself comfortable and hang out a while.

However, I must remind you that we're a "picture hungry" group so try and refrain from making threads without tons of boat/motor pics, ok? LOL

 

[r.j.dawg]

Re: 1986 US Marine Force 50 outboard motor low power

Welcome Tommy....yes, pics please

 

[Jiggz]

Re: 1986 US Marine Force 50 outboard motor low power

Welcome to the forum. The problem you were describing is refer to as "cavitating" because the exhaust is pushing air into the prop make the prop push air instead of water. There is actually a part for that exhaust which is referred mostly as the exhaust snout or simply snout. It also functions to trim the boat or engine tracking. They sometimes sell them on e-bay.

 

[jerryjerry05]

Re: 1986 US Marine Force 50 outboard motor low power

You didn't say if you found the part.
Talk to FrankA.
He might have one in his extras pile???
Or Franz Marine @ aol . com Remove the spaces.