1972 johns 25 hp won't stay in gear

[ziggsdna]

i have a 1972 johnson 25 hp outboard. It starts and runs great. but some times when you are going full speed and every thing seems fine. It will all of a sudden just jump out of gear. i have put two differnt lower units on this motor and still same problem but it dosent happen all the time some times it works just fine and gives me no trouble. is there a part that could be bad in the upper half of the motor if so what i have tried everything i can think of with no help. and im pretty good at working with motors. Please help im restoring a jon boat and really want to use this motor this year.

 

[F_R]

Re: 1972 johns 25 hp won't stay in gear

Does it physically come out of gear--that is does the shift lever move? When it does it, does it go back into gear with a violent bang? Or what do you have to do to get it back into gear?

I ask all those questions because I wonder if it actually is coming out of gear or just "slipping". If it is slipping it could be the propeller hub, although they usually don't self heal and work again, at least not at high speeds. The other thought is cavitation, or more properly ventilation. That is when the propeller sucks air from the surface and runs wild in the big air pocket that develops around the propeller.

Anything that might be bad or broken in the upper part of the motor would not heal. Once it's broken, it's broken.

 

[ziggsdna]

Re: 1972 johns 25 hp won't stay in gear

i have to bring the engine back to idle and put it back in gear but like i said some times it will work just fine. Might i just be out of ajustment in the linkage or some else has told me that the ''dogs'' might be worn out. some times the foward will work fine but no reverse and viseversa which makes me think that the ajustment is of in the linkage or the linkage is bad itself could this be my problemm?????

 

[F_R]

Re: 1972 johns 25 hp won't stay in gear

Very well could be the linkage. Is the interlock bar present on the side of the powerhead? Is the shifter lever tight on the shaft? Aside from that, take the oval inspection plate off the side of the midsection and watch the shift rod as you move the shifter lever. As the lever moves, the rod should move. No slack or delay or slop allowed.

Trouble is, worn or loose linkage will result in worn dog. AND/OR a worn dog if not repaired will eventually beat the linkage loose.

 

[ziggsdna]

Re: 1972 johns 25 hp won't stay in gear

Thank you for your help i was trying to adjust it earlyer todaoy and you are right there is a little slop in the linkage which has to be the problem because i took apart the lower unit and the dogs look just fine no wear. hopefully i can find a linkage that is not made of brass. Or do you know if they are only made of brass??? Anyways thanks for your help i have been fighting with this problem for to seasons luckly i also have a johns 4 horse so i didnt miss out on any time on the water. thanks and happy boating!!!!!

 

[samo_ott]

Re: 1972 johns 25 hp won't stay in gear

While it does sound like the clutch dog is worn, 2 different LU's should eliminate that issue and most other issues in the LU. And if you've been changing LU's then you have been disconnecting the shifter and reconnecting it thus in effect adjusting it.

 

[ziggsdna]

Re: 1972 johns 25 hp won't stay in gear

thanks for the info but you are wrong the adjustmen is made on the shift lever itself no the linkage just for future reffence on giving advice

 

[F_R]

Re: 1972 johns 25 hp won't stay in gear

There is an adjustment for the shift lever in relation to the shaft that it is on. That is the only adjustment. Other than that, any looseness or slop is mechanical in nature. The shift lever shafts get loose and sloppy in the housing where it goes through to the inside. Inside, there is another lever that often comes loose on the shift lever shaft. I'm sure you will find your slop is in one of those areas.

 

[samo_ott]

Re: 1972 johns 25 hp won't stay in gear

Sorry, I was thinking of the disconnect, yes, the adjustment is at the shifter.

 

[ziggsdna]

Re: 1972 johns 25 hp won't stay in gear

Thank you guys for all the help i took it out on tne missippi yesterday and it ran like a top no jumping out of gear at all hopefully it stays that waythanks again and happy boating. p.s. steve sorry for sounding like a **** the other day just one of those days

 

[pet575]

Re: 1972 johns 25 hp won't stay in gear

Hey ziggs, I'm having the same problem with the same motor. I've adjusted the lever and hopefully that will work. Have not looked at the clutch dog yet, though, to see what type of shape it is in. Any recollection what the cost was on one of those lower units? I'm wondering if it might be better to replace it all given its age. Thanks.