1974 Johnson Reverse Questions

[Isaacm1986]

I have a 1978 Johnson 115hp outboard. I have searched the forums for my answer but i cannot find it.

So here is what happens. This year i prepped the boat for the summer. Ran everything on the hose and tested everything. I changed the lower unit oil, installed new thermostats, and she is running great. Forward and reverse work on the hose.

I took it down to the lake for a few laps around the lake. We launched it, and the put the motor in reverse, it just made grinding noises and the boat went no where. We managed to flip the boat around at the dock, and took off. Forward gear worked great. My first thought was it needed a linkage adjustment for reverse gear. But after a few laps around the lake, i tried reverse again and it worked perfectly. I thought the problem had corrected it self. We played around on the lake for a few hours. then headed back in. There was a 15 min wait for a spot on the dock to open up, so we just idled in the waiting area. Once a spot opened up, i drove up to the dock and put the boat in reverse, and it was back to the grinding noise. We loaded up the boat, took it home. I checked the oil and linkage adjustments. fired it up on the hose and reverse worked no problem.

Since then I have had it out a couple of times. To sum everything up. Reverse will work for about 60 seconds after the boat has been running for a bit. But if it cools down to much, then it wont work at all and just make grinding noises. any ideas?

Im using 90w lower unit oil, would wrong oil cause this?

thanks

 

[F_R]

It is just barely engaging reverse gear. Something in the linkage or control is either out of adjustment or worn out. You will have to inspect it on-site to see where the lost motion is. But don't delay, that grinding is very destructive to the clutch dog and reverse gear. Of course it is possible that is already the problem, but be sure the control is actually putting it all the way in reverse before going there.