Have a 97 Evinrude 115. This is on a pontoon boat. Running down the water accelerating and the prop will break loose and the engine justs revs up. Slow down let the prop grab again and off we go only to have it happen again and again. I figured it had to be a spun prop since all indications lead to that. Replaced prop with new prop. Old one was a 13 pitch put a new 15 on it. That did not help as it still does the same thing. I have checked all the obvious, Prop is in water not out. Does not same to matter the trim of the engine. The trim motor is good, the motor never kicks up. Have not hit anything in the water either. Engine runs good no sound of broken gears grinmding or any of that. I am just stumped. Do you have any ideas? Thanks
The prop may be in the water but where is the anti cavitation plate. It must be in the water as well, riding on the water on plane, or the prop will cavitate, (break free).
Posts: 1403 | Location: Fenton, Mo USA | Registered: Feb 18, 2004
Yes, that too is in the water. It will happen with the motor trimmed all the way down also. There seems to be no certain postion where it does it more than another.
Boy I would have thought it was a spun Hub on the prop. You say you changed props. It's a long shot but could the new prop be spun also. Do you have an old prop in good working condition? Or can you borrow one from a good friend or relative until you can ck. this out. Please post your findings as this is very puzzeling.
OLDMAN
Posts: 457 | Location: owosso,mi. usa | Registered: Oct 05, 2003
I put on the 15 pitch prop but that slowed the RPM's down to much. Went from 5500 to 4000. So I put the old 13 back on. Usually if a prop is spun you can see the rubber torn or the thrust washer with "spun" markings on it. That was not the case.
I took a bunch of my kid's freinds with me for an outing. We put 12 teenagers on there so naturally it "sank" the engine farther in the water. I tried all day to get that prop to break (which is the OLD 13 pitch)but I couldn't do it no matter what I did or how hard I tried.
The next day I went for a ride by myself and still it would not break loose. After talking to several people, some mechanics, all anyone could come up is that is really strange. Not one of them thought it was engine related. Thought it was a weight issue to much up front. Nothing had changed since I bought it. One thought the pontoon logs may be to dirty and that caused it. I will clean them but they are not very bad.
I don't know why or have any ideas. All I can say is I am baffled just like everyone else.
DONT KNOW IF THIS WILL APPLY ON A PONTOON BUT HAD A SIMILAR PROBLEM WITH A 16FT DURACRAFT MOD V HULL.......HULL HAD A SLIGHT CREASE NEAR THE STERN PROBABLY CAUSED BY RUNNING OVER A TREE STUMP....DEALER SAID THIS WAS CAUSED A CAVITATION PROBLEM. PRETTY MUCH ELIMANATED PROBLEM WHEN HULL FIXED...........
