1962 Johnson 40hp Gear slipping?

[hodgie]

I got the boat in the water today after changing the impeller and the oil and everything was running great. Then once I got the throttle close to full something gave. It seemed like the motor revved up but the boat was slowing. Sounds like a gear jumping to me but could it be a spun prop? My prop has a shear pin? It did this a few time and always when the throttle was almost fully engaged. I would have pull back on the throttle to get going again. Everything was fine at slower speeds. My motor is an electric shift if that helps. I did use Type-C oil in the lower unit.

Model # RK-24L
Serial: 2288360

Thanks for the help

 

[Mas]

Re: 1962 Johnson 40hp Gear slipping?

Maybe a spun hub. Take the prop off and mark a line from the hub to the outside of the prop. Run the motor again on the water, then take off the prop again and see if your marks moved relative to one another.

MAS

 

[Mark_VTfisherman]

Re: 1962 Johnson 40hp Gear slipping?

...Sounds like a gear jumping to me but could it be a spun prop? My prop has a shear pin? It did this a few time and always when the throttle was almost fully engaged. I would have pull back on the throttle to get going again. Everything was fine at slower speeds. My motor is an electric shift if that helps. I did use Type-C oil in the lower unit....

Mas said, "Maybe a spun hub"

...or a worn out shift coupler. Spun hubs don't usually have a sound- mine never did. I mean other than me bellyachin' for a minute or two:redface:

The shift coupler will make a nasty sound when it slips: THAT does sound like a gear jumping.

I don't have any of those parts anymore but I would send you one if I did. Not hard to change but is a job for a mechanic if you don't feel up to it.

 

[tashasdaddy]

Re: 1962 Johnson 40hp Gear slipping?

did it feel like you hit something, any grinding noises.

 

[freddyray21]

Re: 1962 Johnson 40hp Gear slipping?

I had the same problem on an almost identical motor last year. The solenoids in the lu need a good 12 volts and if your battery is low it will cause it to slip like that.

 

[freddyray21]

Re: 1962 Johnson 40hp Gear slipping?

btw when mine did that is only did it at higher speeds. At lower speeds it was fine too

 

[Mark_VTfisherman]

Re: 1962 Johnson 40hp Gear slipping?

I think the electric and manual shift lower units used the same shift coupler (also called shift dog). It still sounds a little like the shift coupler is worn and camming out. Never ran an electric shift so can't address that, but if the shift coupler is worn a little, it makes sense that low batt voltage will result in low energy at the solenoids so that could be a contributor or the culprit. I actually have never heard of any problems with the lower unit gears in one of those old Johnsons, but I am not a marine mechanic either-just been around them for the last 20+ years.

My manual shift '64 Johnson 40 used to be fine at most speeds, but I had a bungee cord to wrap around the shift lever when throttled up to keep it from popping out. I finally got sick of it and took the thing apart, was amazed at how simple it was designed, and replaced the parts. There are two pieces that wear out where they mate.

In conclusion, if your solenoid or battery is the culprit, get 'it fixed- every time that thing pops out, it is wearing out the dogs on the shift coupler.

 

[hodgie]

Re: 1962 Johnson 40hp Gear slipping?

Thanks guys for all the help. I know I didn't hit anything and there wasn't a grinding noise. The battery is new and was fully charged. I will still check the voltage to the lu. The best way to explained what happened is like the motor was running wot but the prop wasn't moving at all. It was like it just released. The previous owner replaced a gear 2 years ago. Not sure what it was called but it sits vertical in the lu and attaches to the drive shaft. It had a chipped tooth. He didn't have the boat in the water after the repair. I should have my manual today and will start to learn a lot about this motor once I get it apart. Just want to no what to look for before I start.

 

[lindy46]

Re: 1962 Johnson 40hp Gear slipping?

Thanks guys for all the help. I know I didn't hit anything and there wasn't a grinding noise. The battery is new and was fully charged. I will still check the voltage to the lu. The best way to explained what happened is like the motor was running wot but the prop wasn't moving at all. It was like it just released. The previous owner replaced a gear 2 years ago. Not sure what it was called but it sits vertical in the lu and attaches to the drive shaft. It had a chipped tooth. He didn't have the boat in the water after the repair. I should have my manual today and will start to learn a lot about this motor once I get it apart. Just want to no what to look for before I start.

That would be the pinion gear - symptoms don't sound like that is your problem.

 

[Mark_VTfisherman]

Re: 1962 Johnson 40hp Gear slipping?

That would be the pinion gear - symptoms don't sound like that is your problem.

Agreed. Thought: I think the yoke that actuates the shift dog is adjustable from the solenoid- that rod has a limited amount of adjustment. A fussy thing. I am still betting on the shift dog/coupler.

 

[hodgie]

Re: 1962 Johnson 40hp Gear slipping?

Here is my latest update:

My old prop was in bad shape so I went ahead and replaced it with a used one that I found for sale. I got the boat on the water this weekend and seemed to be working great. Boat was able to plane and I finally got some speed. However, after slowing down and then speeding up again I had the same thing happen. Motor stayed at the current RPMs but the boat slowed until I pulled the throttle back toward neutral. Now, what I did find out by playing with it the rest of the day is if I eased the throttle forward very slowly until the boat was able to plane and held it there the symptom that I was having didn?t happen. I was able to control it for the rest of the day without any problems. I did try to throttle it faster again just to test my theory and sure enough it happed. As a side note I did notice that the throttle lever was very difficult to push toward WOT. And once there I would have to hold it in place or it would come back on its own. Do you guys still think this is the clutch dog and what is causing the throttle to be so tight that it pulls back on its own?

Thanks,

Bryan

 

[tx1961whaler]

Re: 1962 Johnson 40hp Gear slipping?

Used prop could have been spun too.
One way to find out: Take the prop off, draw a straight line across the prop across the centerline (across the inner and outer parts of the prop), put the prop back on and run it. If it slips, the marks won't line up anymore.

 

[Chinewalker]

Re: 1962 Johnson 40hp Gear slipping?

Electric shift lower units don't have a shift dog. In neutral (no current) the gears spin freely on the propshaft and utilize a spring with the electro magnet to engage the selected gear to the propshaft. It is possible with low current to have the selected gear slip under load.

Not to be confused with the later hydro-electric shift units, which do use a clutch dog.

- Scott

 

[Mark_VTfisherman]

Re: 1962 Johnson 40hp Gear slipping?

....Not to be confused with the later hydro-electric shift units, which do use a clutch dog

Scott- thanks for the info. I, however, was confused as I was only familiar with electric shifts that used a clutch dog.

 

[hodgie]

Re: 1962 Johnson 40hp Gear slipping?

So I guess the questions are:

Does an electic shift even have a clutch dog?
Is it an easy to fix the tight throttle problem I am having?

thanks again for all the help

 

[Mark_VTfisherman]

Re: 1962 Johnson 40hp Gear slipping?

Does an electic shift even have a clutch dog?
Is it an easy to fix the tight throttle problem I am having?

The electric shift I scavenged parts of from had a clutch dog. Think it was mid/early 70s? Chinewalker knows a lot more about this- I apparently don't know everything- again and I am good with that.

Throttle stiff: That I do know about. Take apart your helm and see if it moves freely with the cable disconnected. If not, take it apart and clean and lube everything. That should free it up. If not, make sure there is nothing bending the cable too sharply and check for kinks under the sheathing. A bent cable will be stiff. They are usually SS so probably not rust, but the sheathing has regular steel in it, which can create a bind if moisture has gotten to it and it has rusted. If the cable is faulty then replace it. It is a pretty simple system so it should be easy to find the issue and to fix it.

 

[tx1961whaler]

Re: 1962 Johnson 40hp Gear slipping?

So I guess the questions are:

Does an electic shift even have a clutch dog?
Is it an easy to fix the tight throttle problem I am having?

thanks again for all the help

A 1962 40 HP electric shift lower unit does not have a clutch dog. If it's not the prop, or the shear pin, then it's the springs in the lower unit. I would definitively eliminate the prop as a problem before going any further. I have three spun 40 hp props laying around that I can sell to anyone, so please confirm that the one you have (you didn't say where it came from) is not spun.