115 HP Johnson 90 jumps out of gear?

[Pettyjohn82]

I have a 1978 Johnson 115 HP 90 series outboard engine I believe model is 115LM78C and while driving last week for the first 1 hour I was pulling a tube off and on then the boat seemed to all of a sudden kick out of forward and jump into neutral making the engine rev way up then within a couple seconds kick back in putting strain of course on transom. It did it intermittently then all of a sudden more often so I stopped to check under the hood. The only thing I saw was part of the shield for the air intake on one side had been unscrewed and just laying in there but the engine of course was getting same air flow just without the guard. I started it back up and it ran great but when I put it in reverse or forward...nothing but the engine revving up? I could not feel that normal thud when putting in gear and the boat wouldn't go forward or backwards. I brought it out yesterday with muffs and put it in forward and reverse and the propeller was turning but still heard or felt NO thud? Afraid to take it out again without knowing what's wrong. Any ideas????

 

[jakedaawg]

Drain lower and look for metal in fluid

 

[Pettyjohn82]

Ok I will drain it in a couple of days and let you know.

 

[emdsapmgr]

Could be a problem with the shift cable. Disconnect the shift cable at the engine. Start the engine and try shifting by hand. What happens when you manually shift it between forward, neutral and reverse?

 

[Pettyjohn82]

I will try it tonight....so even though it goes into forward and reverse while running with the cable it could possibly still be the cable? If I do it manually and feel the clunk then the cable could need replaced? I am going to change the gear oil like jakedawgg said also. I will give update tonight. Sorry also engine model is 115ML78C Thanks

 

[Pettyjohn82]

I still need to start the engine and manually shift in gears but I did change the lower oil and only small shavings on the drain plug. I didn't see any actual alarming shavings or pieces. It did smell bad however and really dark. I will start it and try to shift manually tomorrow. What should the RPM be at idle before shifting into forward or reverse. It is currently around 1200. Any other feedback will be much appreciated.

 

[ondarvr]

Stinky lower unit oil is normal. It should idle around 650-700 RPMs, 1200 is way too high.

 

[emdsapmgr]

650-750 idle rpm's when the boat is floating normally in the lake, and the engine is shifted into forward gear. You can't set it when it's on the trailer.

 

[Pettyjohn82]

When I manually shift it into gear like suggested above is it ok to shift it around the 1000-1200 RPM range out of the water or should I back the idle down while I have the muffs on and am working on it because I plan on doing that tonight? Thanks

 

[interalian]

When I manually shift it into gear like suggested above is it ok to shift it around the 1000-1200 RPM range out of the water or should I back the idle down while I have the muffs on and am working on it because I plan on doing that tonight? Thanks

No need to worry if your idle is higher on muffs. There's no resistance on the prop when you shift it out of the water. Always remember to be quick/deliberate when shifting - no sloooow engagements whether on muffs or on the water.

 

[Pettyjohn82]

Well I shifted it manually and same thing no thud but the propeller still goes forward and reverse. I don't know what else to do??????

 

[interalian]

Going back to your earlier comment about the air intake being loose - do you mean the aluminum housing was loose on the front of the carbs? How loose? That would affect the amount of engagement of the shift and throttles.

 

[Pettyjohn82]

Sorry wasn't too clear....it was just one of the plastic extensions on the left side. The other was fine. I had taken it off to get to a fuel hose that was leaking and apparently didn't tighten it back up. The weird thing is the boat shifted fine and ran fine until I took the throttle cable and shift cable off to get to the leak. I just don't understand when I was shifting it manually yesterday with the cable off why I still don't feel a kick or thud when I was putting it in gear. Like I said the propeller still spins in both directions and goes faster with more throttle? Maybe I should put it in the water again just don't want to be stranded and just doesn't seem right.

 

[interalian]

When the shift linkage is in neutral, is the arm vertical? Just to confirm the cable is adjusted correctly, remove it from the shift lever and center the shift arm. Set the remote control to neutral and adjust the trunnion on the cable (if required) to allow the shift cable to slide on to the stud without moving the shift arm. Secure all fasteners and test it in the lake.

 

[Pettyjohn82]

I actually did think to adjust it yesterday when I put it back together but what's weird is there is a little play in neutral meaning before I was shifting it manually I could wiggle the arm a little before. Not as much play of course like you would see in a manual transmission on a vehicle while in neutral lol but it does have a some play before kicking in forward and reverse. More then what I feel it should have but this is the first boat I have owned so maybe just me. I will try to take it out very soon in the next couple days after I buy a trolling motor for backup.

 

[Pettyjohn82]

Before I take the boat out does anybody have an opinion on wether there is supposed to be play between neutral and forward.....neutral and reverse? It's quite a bit in my opinion probably an inch before of play both ways before it starts to have resistance to go into gear.

 

[Pettyjohn82]

Still does it in the water.....2 things come to my mind. Clutch dog or gears are sheared which I'm not sure how likely that is because the odds of both getting sheared at the same time???? Second thing is possibly shifter rod. There is a bunch of play between neutral and forward /reverse. I manually shifted so know it's not cable however do these sound like possible solutions before I tear into the lower unit? Thanks