Shift Rod or Something Else?

[mechanicallyDeclined]

Hi,
Everything was running fine on my 73 Johnson 50hp outboard until I discovered cloudy lower gear unit oil. After a pressure test and submerged lower unit, I identified leaks by the shift rod and drive shaft. I replaced the back-to-back seals below the shift rod housing and a gasket on the drive shaft bearing housing. A quick pressure test confirmed no more leaks.

Took it to the lake only to find out that it would not shift into forward--only reverse. It would shift into forward but only at really high throttle/rpms. My first guess was that I did not adjust the shift rod correctly (though it was the exact height of when I removed the lower unit when everything was shifting fine).

Instead of removing the lower unit, again--I made an adjustment on the shift cable. It did not seem to be aligned correctly, anyway, so thought it was worth a try. Now, when I shift into forward it switches gears smoothly--but I no longer get high throttle/power.

So, the only things that I potentially changed are the shift rod height (maybe) and the shift rod cable. These are my primary suspects--but why and how would they impact throttle speed? Coincidence? Perhaps another issue with a bad throttle cable or bad gas?

Can you point me in the right direction? Thanks!

 

[Crosbyman]

25 50 200 ???

 

[mechanicallyDeclined]

25 50 200 ???

Sorry--50hp

 

[racerone]

Need to be clear.----Were there back to back seals below the shift rod housing ??----This unit shifts with oil pressure and unit needs to be full of oil.----No it is not electric shift.----If it slams into forward at high revs it can damage the clutch dog.

 

[racerone]

Shift rod has to be set to a specific dimension.----Was that done?----Is motor long or short shaft?

 

[mechanicallyDeclined]

Need to be clear.----Were there back to back seals below the shift rod housing ??----This unit shifts with oil pressure and unit needs to be full of oil.----No it is not electric shift.----If it slams into forward at high revs it can damage the clutch dog.

Sorry for the confusion. I replaced one "o" ring in the shift rod cover assembly (the small one that is a bit tricky to remove). I also replaced the two oil retainer seals on the driveshaft (just below the water pump, inside the drive shaft bearing housing). I filled lower gear unit with oil until oil pushed through the oil vent plug.

 

[racerone]

Set the shift rod to the correct height.----Short or long shaft motor?

 

[mechanicallyDeclined]

Shift rod has to be set to a specific dimension.----Was that done?----Is motor long or short shaft?

Long shaft. I removed the lower unit in neutral and recorded the distance to make sure I reinstalled the same (21"). Specifications in the original manual are 21 7/32" with the gear in reverse. In my mind, I thought I was putting it back as it was, and, imagined that reverse would increase the height of the rod and most likely hitting the height requirement. I know that might be wishful thinking, and I would think this is the cause of my problems if it wasn't shifting after I made a cable adjustment.

 

[racerone]

Try setting that dimension with gearcase in neutral.

 

[mechanicallyDeclined]

Try setting that dimension with gearcase in neutral.

I did consider that on reinstallation—though it would not be following the manual and I felt that there might not be much thread left to raise it that height. I’m confused still how the shift rod height and cable might prevent more throttle—and I wanted to double check before taking everything apart. It idles great and moves in forward great—just gives nothing more after I reach about 40% throttle. Even moving the gear box lever all the way forward does not result in anymore power. Can a shift rod at the wrong height explain this? Thanks for your input!

 

[racerone]

Post the results of a compression test.----And check to make sure it has spark on both cylinders.----Sounds like it is running on just 1 cylinder.

 

[mechanicallyDeclined]

Post the results of a compression test.----And check to make sure it has spark on both cylinders.----Sounds like it is running on just 1 cylinder.

Spark to both plugs. Top cylinder is getting about 119 and bottom cylinder is getting about 116. I wasn't able to get the motor running (of course that would be the case :/) It would fire off for a second or so and then quit. So, the compression test was not able to be completed on a warm engine. Thoughts?

While poking around, I also happened to notice a small torn hose, which I believe is the air silencer to manifold. I can't imagine this is the cause of my troubles?

Thanks for any insights you might have.

 

[mechanicallyDeclined]

Hi,
Everything was running fine on my 73 Johnson 50hp outboard until I discovered cloudy lower gear unit oil. After a pressure test and submerged lower unit, I identified leaks by the shift rod and drive shaft. I replaced the back-to-back seals below the shift rod housing and a gasket on the drive shaft bearing housing. A quick pressure test confirmed no more leaks.

Took it to the lake only to find out that it would not shift into forward--only reverse. It would shift into forward but only at really high throttle/rpms. My first guess was that I did not adjust the shift rod correctly (though it was the exact height of when I removed the lower unit when everything was shifting fine).

Instead of removing the lower unit, again--I made an adjustment on the shift cable. It did not seem to be aligned correctly, anyway, so thought it was worth a try. Now, when I shift into forward it switches gears smoothly--but I no longer get high throttle/power.

So, the only things that I potentially changed are the shift rod height (maybe) and the shift rod cable. These are my primary suspects--but why and how would they impact throttle speed? Coincidence? Perhaps another issue with a bad throttle cable or bad gas?

Can you point me in the right direction? Thanks!

I will post any updates or resolutions if I discover the underlying issue. Please send me any ideas if there is something I should consider—as I’m still trying to get to the bottom of this! Thanks!

 

[mechanicallyDeclined]

Hi,
Everything was running fine on my 73 Johnson 50hp outboard until I discovered cloudy lower gear unit oil. After a pressure test and submerged lower unit, I identified leaks by the shift rod and drive shaft. I replaced the back-to-back seals below the shift rod housing and a gasket on the drive shaft bearing housing. A quick pressure test confirmed no more leaks.

Took it to the lake only to find out that it would not shift into forward--only reverse. It would shift into forward but only at really high throttle/rpms. My first guess was that I did not adjust the shift rod correctly (though it was the exact height of when I removed the lower unit when everything was shifting fine).

Instead of removing the lower unit, again--I made an adjustment on the shift cable. It did not seem to be aligned correctly, anyway, so thought it was worth a try. Now, when I shift into forward it switches gears smoothly--but I no longer get high throttle/power.

So, the only things that I potentially changed are the shift rod height (maybe) and the shift rod cable. These are my primary suspects--but why and how would they impact throttle speed? Coincidence? Perhaps another issue with a bad throttle cable or bad gas?

Can you point me in the right direction? Thanks!

Update: To rule out bad gas, I bought a one gallon gas can, filled it with 91 fuel, added 50:1 oil ratio, and--because I thought it might help clean the carbs--poured an entire can of seafoam in as well (a sign of desperation I'm sure you will think) . After priming the bulb and attempting to get the idle throttle up while starting--the engine fired right up and ran well up and down. Turned it off, tried starting again, and it fired right up. This led me to believe the gas in the old permanent tank from fall was bad--so removed as much as possible by siphoning the gas and filled the permanent gas tank with 8 gallons of fresh gas + 50:1 oil ratio. Got to the boat landing--tried to start it--and it just wouldn't go. Argh.

So, I'm thinking that when I tried the small tank, that the added seafoam created a leaner mix? So, might I need to adjust the lean/rich on the motor?

 

[mechanicallyDeclined]

Update. Fixed. Brought the motor to a mechanic (imagine that). Compression seemed fine. Spark plug coils not getting enough spark (enough that I could see them--but maybe not strong enough?). Isolated the issue to a bad power pack. Replaced power pack. Tested in water. Determined it also had a bad ignition coil. Replaced. Now works. I hope this explanation makes sense. I'm going off of memory from when we got it working at the end of last season--just in time to winterize it :/. Thanks for all the suggestions on the forum--those that suggested that it was only running on one cylinder were correct!