Prop Problem related to Jumping out of Gear?

I have a 1979 Evinrude 25 hp that jumps out of gear as throttle passes 1/2 way. I know the shift dogs are in good shape, and I don't detect any problem in the linkage. I'm getting vibration though and prop has some damage ....Could the excess vibration from a bad prop cause my engine to jump out of gear?

Re: Prop Problem related to Jumping out of Gear?

Is it thumping like when the dogs are bad or just slipping?
Vibration from the prop might cause it to jump and if you have been running for an extended time with vibration the gearcase could be damaged.Is it remote controls or tiller?If its on cables unhook it and see if it shifts by hand.
Get the prop repaired and if its slipping you may need a rehub.

Re: Prop Problem related to Jumping out of Gear?

There is no thumping, and the motor is on a tiller. There appears to be no slipping, and then it completely jumps out of gear just before boat starts to plane. I'm going to replace the prop anyhow since I need to eliminate the vibration and go from there. I'll let you know what happens.

Re: Prop Problem related to Jumping out of Gear?

Sounds like a spun hub and if it was bad enough it might cause a vibration.
If it was the dogs it would thump.

Re: Prop Problem related to Jumping out of Gear?

The problem wasn't the prop. I replaced it and still have the same problem, although it is slightly smoother. I'm going to examine the linkage next, maybe it's just sloppy.

BTW, with a spun prop wouldn't the shift stay engaged?

Re: Prop Problem related to Jumping out of Gear?

Ultimately what I found was that the problem was with the shift lever. Rather than starting with the shift dog and forward gear, which I replaced , I would urge folks to start at the top with the shift lever. It looks like it doesn't take much to crack the mount on the lever which is hidden from view on my model. My guess is that that motor was on its side, maybe not put down gently enough, and it cracked a piece off where it mounts to the linkage. The lever still worked and would engage but was sloppy and the linkage could slip behind it. Take apart the shift lever and check for damage on these models before you decide to rebuild the lower unit, you'll save a lot of expense and aggravation.