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Jumping out of gear

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Articcat1010

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Hi everyone, just signed up to this site. Looking for some advise before I take it to mechanic. I have 1999 75 hr merc outboard on my 24ft pontoon. While cruising, the motor seems to jump out of gear!
Once I throttle down it seems to correct itself. It's fine if I'm at low speed but when I go over half throttle it does it again. I'm I looking at big or small fix here? Help in Ny. Thx steve
 
Are you sure it is jumping out for gear. If you let off the throttle, it would not go back in gear if that is what is happening. My guess is you are having problems with your prop. It is slipping a higher rpm's.
 
Thx for replying btw.. I didn't know that the prop could slip ! How do I tell if it's slipping.? Thought it went on only one way with lockring nut
 
If the motor were jumping in-and-out of gear it would feel like someone is pounding on the transom with a 4x4!

Most likely what you are experiencing is a slipping rubber hub in your propeller. The rubber hub, which is bonded to the center splines of the prop, is pressed into the propeller under high pressure. The rubber can deteriorate and then it will slip, causing your rpm to rise under load without a commensurate increase in boat speed. When you back off the throttle, you reduce pressure on the hub to where it'll drive the prop again. Eventually it'll wear out and the prop won't drive at all in gear.

Best way to check is to mark the body of the prop with a Sharpie or scribe, then make a match-mark to the center hub. Run the boat and when the prop slips, check the marks. If they're no longer aligned with each other, the rubber is shot. A propeller shop can re-hub the prop for a nominal fee; if your prop is otherwise in good condition you'll save a bit over purchase of a new prop.

HTH & let us know what you find..........ed
 
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