Older Johnson 18hp jumps in and out of gear

[jon75127]

I am helping a friend with a 1961 FD-15 18hp that jumps in and out of forward gear after reaching 1/4 throttle and above. He says he can see the shift lever move in and out of gear. This is a long shaft, tiller motor. Reverse works fine at all speeds.

I tested the bellcrank according to the service manual, and all checks out. I researched the clutch dog, but read that the motor would not go back into gear after it jumps out.

Any ideas out there??

 

[tmcalavy]

Re: Older Johnson 18hp jumps in and out of gear

Is the notched bar that holds the shifter in place (F-N-R) there and functional? If he can see the shift lever jump around, it may not be holding tight. Best I remember there is a spring on the top of the notched bar that provides tension so the shift lever will stick in the notches when it is moved. If that spring is gone, no workee-workee...nothing to hold the shift lever in place/gear.
If the shift lever holder (notice my fancy terminology) is tight and working right, it may be time to look into the foot and check the yoke that holds the clutch dog in place...it could be busted or not properly anchored. You'll need plenty of tasty beverages for that one and at least four hands/arms and two heads. It tries your patience. You'll also need a service manual at the very least. If anything in the foot is toast, replacing it with another entire functioning foot (check the auction sites) may be cheaper than the parts...the foots/feet are interchangeable among many year models of the same hp.

 

[F_R]

Re: Older Johnson 18hp jumps in and out of gear

If the clutch dog and gear are that worn out (jumping at 1/4 speed), nothing in heck will hold it in gear at high speeds.

There are only two cures:
1: Replace clutch dog and forward gear. Dig deep in your pockets for this cure.
2: Replace motor. Keep digging.

Well cure #3 might be replace lower unit. IF the replacement is good.

 

[jon75127]

Re: Older Johnson 18hp jumps in and out of gear

Thanks for the help. I did check the mototr and the notched bar, shift lever, and spring are all there and intact. Looks like we are in the market for a new lower unit.

 

[tmcalavy]

Re: Older Johnson 18hp jumps in and out of gear

Keep an eye on the auction site. The Johnson 18 hp started out as a 15 hp (mid 50's) and didn't change much for a decade. Many years will share that same lower unit...trick is to find one used, not abused.