1975 Johnson 15hp Wont Stay In Gear At High RPM's

hey guys,

my old 1975 Johnson 15hp Outbaord wont stay in gear above about idle speed, unless i hold the shift lever in place and when it comes out of gear the shift lever dosent go back to neutral it moves back about 3cm [enough so that its out of gear but can still rev]

any suggestions on a repair, thought i'd better ask before i pull the leg and gearbox apart when all that was needed was a new screw or something easy

thanx

Re: 1975 Johnson 15hp Wont Stay In Gear At High RPM's

Sounds like your linkage in the lower unit has slipped. If I remember right there is an inspection plate halfway down the midsection. It is only 2 screws to remove. You will see the brass screws that hold the shift rod from the engine to the shift rod from the lower unit. You can also check out diagrams from several sites.

Re: 1975 Johnson 15hp Wont Stay In Gear At High RPM's

browndog185 said:

hey guys,

my old 1975 Johnson 15hp Outbaord wont stay in gear above about idle speed, unless i hold the shift lever in place and when it comes out of gear the shift lever dosent go back to neutral it moves back about 3cm [enough so that its out of gear but can still rev]

any suggestions on a repair, thought i'd better ask before i pull the leg and gearbox apart when all that was needed was a new screw or something easy

thanx

Click to expand...

Change the clutch dog, the forward gear is probably also damaged. Not cheap.

Re: 1975 Johnson 15hp Wont Stay In Gear At High RPM's

I agree with torbjorn. Assuming the shift linkage is ok, then you have a worn out clutch dog. It happens in these older motors after enough years. I just had to change the one on my 10hp, and it made all the difference in the world. Unfortunately, they're usually not the cheapest part ($65 for my 10hp), but if look on ebay or go to a good scrap yard, you may be able to get one for quite a bit less than a brand new one, if you're lucky. I got super lucky and my local, good 'ol boy mechanic happened to have a like-new one and gave it to me for free!!!!! Always support the local guy It may be worth the effort to find an entire donor lower unit in case you need any other bits too. If you have a local mechanic he may have a pile of old parts motors in the back that you can get a donor LU off of. Doesn't always work, but it might be worth a shot. Once you get the part, it's not very hard to install. You will have to access and remove the gears to replace the clutch dog, but it's not too bad and it's pretty interesting and informative to see how everything works in there. Keep us posted. Good luck!

Re: 1975 Johnson 15hp Wont Stay In Gear At High RPM's

Well I agree more with Fireman. If the clutch dog was slipping the shifter would slip with it, not go out of sinc. Did anyone unscrew that phillips screw in the lower unit, perhaps by accident when changing the lower unit oil?

In any event if it is the linkage and it is not the connection between the mid-section and lower unit (unlikely would cause your type of problem, but an easy check) and no one took out that phillips screw (your shifter pivots on this and would definitely cause the problems you are experiencing) then it is the linkage inside the gearbox. In that event the gearbox has to be dissassembled and you can look at the clutch dog at that time. Fix whichever one it is.

Re: 1975 Johnson 15hp Wont Stay In Gear At High RPM's

Sorry Fireman57 but the inspection plate was for the series of motors just prior to the 9.9/15hp motors.

If you can't find a clutch/shifter dog slider, sometimes you can just swap ends & let the reverse side of the dogs engage the forward gear. Not ideal, but in a pinch may work.

Re: 1975 Johnson 15hp Wont Stay In Gear At High RPM's

That's what I get for working from memory!

Re: 1975 Johnson 15hp Wont Stay In Gear At High RPM's

This worked for my 9.5 Evinrude

the machinist said:

Sorry Fireman57 but the inspection plate was for the series of motors just prior to the 9.9/15hp motors.

If you can't find a clutch/shifter dog slider, sometimes you can just swap ends & let the reverse side of the dogs engage the forward gear. Not ideal, but in a pinch may work.

Click to expand...