1987 Johnson 50 Slipping out of gear

[MTribe08]

Hey guys,
Helping out a friend of mine that inherited a pontoon boat with a Johnson 50 2 stroke. On one of the last trips the boat made before he got it the boat was cruising along and all of a sudden slipped out of gear and lost propulsion. They took into into a shop and the guy said it was the Pin and the lower unit. He apparently fixed the pin but said something is probably still wrong. So today we put the boat in the water for the first time since he's had it. It goes in and out of gear just fine, forward and reverse, gets going up to speed just fine but when you really try to accelerate to the higher RPM range it still wants to slip out of gear. Any idea what may be going on? Is the lower unit shot, or is this maybe an easy fix?
Thank for any help or insight you may be able to give us.

 

[racerone]

Try another propeller !

 

[MTribe08]

What makes you think its the propeller? Is it not a very common symptom that we are having if we had a bad lower unit? Are you thinking it may be cavitating at high RPMs?

 

[interalian]

The hub has a rubber bushing that's designed to absorb shock loads such as striking a log or rock. If you're slipping at high RPMs, likely that bushing is slipping. As designed.

 

[MTribe08]

Ok Thanks. We arent sure if they hit a rock, but the prop definitely is worn. Not bent, but paint gone ect. Probably time for a new prop. As far as this bushing slipping, just need to replace the bushing to get rid of the problem?

 

[interalian]

Prop shops can replace the bushing and fix damaged blades. Likely easiest to swap a new one, but consider a new bushing for the original and keep as a spare.

You can confirm it's slilpping by marking across the nut and body of the prop, run the boat and see if the marks move.

 

[flyingscott]

Does it bang out of gear or just slip and suddenly rev

 

[MTribe08]

Haven't been able to get back to the water to check if the prop is slipping however, I do know that when the problem happens sometimes we can back the throttle down a little bit and it will reengage and other times you need to back it down alot further. As long as we dont reach a certain RPM its fine. Strange.

 

[Bosunsmate]

try the marking idea suggested by interalian. Sometimes if you look closely you can see that the bushing has being slipping

 

[MTribe08]

Ok, will do. Its entirely possible thats whats going on. Will try and report back.