Engine Revs But Tops Out At ~ 10mph

[thedukeryan]

I picked up a new 1980 Glastron with I believe a 96 80hp Mercury outboard. I just brought it home today and have not had a chance to do anything with it. The previous owner said that the boat runs great but much past 10mph it just revs up with no increase in speed. The current prop is torn up with lots of bite marks from hitting something. He also admitted that the problems acured after the stainless prop was stolen and replaced with a old prop his brother in law had. To me it really sounds like a spun hub but he seemed to think it was something to do with the shift cable. I know in the past I have been able to diagnose a spun hub on my alpha one by putting it in drive and spinning the prop with out spinning the shaft. Does this apply to smaller outboards as well? The reason I ask is because I can force the prop to spin on it while in drive but the shaft turns as well. Its currently to cold to try to take it out and I am going by what he said only. Anyway to diagnose whats going on with it on the trailer?

 

[JB]

Re: Engine Revs But Tops Out At ~ 10mph

I agree with your "probably a spun hub" diagnosis.

 

[walt-oxie1]

Re: Engine Revs But Tops Out At ~ 10mph

It is either a spun hub or a barge prop on it. What hole is the pin in on the transom bracket? Is it a short shaft where a long shaft should be?

 

[jake505]

Re: Engine Revs But Tops Out At ~ 10mph

could be the wrong prop maybe. if the pitch and diameter are way to wrong for that motor.

 

[thedukeryan]

Re: Engine Revs But Tops Out At ~ 10mph

could be the wrong prop maybe. if the pitch and diameter are way to wrong for that motor.

Well I am pretty sure it is a prop issue but being 40 degrees out I am not ballsy enough to take it out and try to diagnose it. Can someone offer me some advice on what pitch & diameter I should be looking at? It is a 16' Glastron with a 80hp Mercury. Gonna try to pick up a used one this winter and have it ready for next year.

It is either a spun hub or a barge prop on it. What hole is the pin in on the transom bracket? Is it a short shaft where a long shaft should be?

Not really sure. It does have hydraulic tilt/trim though.

 

[Paul DuLaney]

Re: Engine Revs But Tops Out At ~ 10mph

If you go the Mercury web site and check out props,put in your information it will give a a good idea of of what to get.