Topic: 1955 Johnson 10 HP QD-16, driveshaft won’t engage with lower unit

This topic has 10 replies, 7 voices, and was last updated 2 years, 2 months ago by billw.

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May 8, 2023 at 6:42 pm #276050
Chad Reeves
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Good afternoon to all!

I am having a problem with my QD-16 and I am needing help understanding what might be causing the problem so I can hopefully fix it. After sitting in storage over winter, I got out my engine to take the the lake. Before the lake trip though I ran it in my tank at home to make sure everything would check out okay. I noticed that there wasn’t spark on one cylinder, so I pulled the flywheel to check the points but when I would turn the prop, the check the point gap, the crankshaft would not turn with it. Conversely when I would turn the crankshaft the prop would turn with it. I dropped the lower unit to make sure the teeth on the driveshaft were aligning with the teeth in the power head, all looked good. With the lower unit off I turned the prop and yes the driveshaft was engaging and spinning with it. I put the lower back on, but I still had the same problem where when I turned the crankshaft the prop would turn but not the other way around. Is it possible that the teeth on the lower end of the driveshaft have shifted, inside the lower unit, just enough to keep the crankshaft from turning when the prop turns due to too much resistance? Though there is enough “grab” with the gears to allow the opposite to happen since there is less friction? Or could it be something else all together?

Any help is greatly appreciated!

Chad
May 8, 2023 at 7:05 pm #276051
aquasonic
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US Member
I’m thinking that you may just have a broken shear pin. It’s hard to turn the motor over from the prop, but easy to turn the prop from the powerhead.

Improvise-Adapt-Overcome
May 8, 2023 at 7:07 pm #276054
labrador-guy
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US Member
Did you check the sheer pin in the propeller?

dale
May 8, 2023 at 8:56 pm #276057
Tubs
Participant
Delete

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.
May 9, 2023 at 2:34 am #276076
Chad Reeves
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US Member
Hello! Thank you for your responses, no it is not the shear pin. I checked it first and it is in tact. Honestly, after working on it this evening I am beginning to think that inside where the powerhead connects to the driveshaft is stripped. I did notice that it was quite rusty up inside the hole where the driveshaft connects to the powerhead, when I shined a flashlight up inside I could see it, maybe this rust caused it to strip? The end of the driveshaft looks that engages with the powerhead looks to be in good order. I only paid $33 for the engine, when I got it I did not know it at the time but it had a cracked flywheel which was an easy enough fix at the time. I replaced the magneto system, did a carb job and I replaced the water impeller. It worked well about 1/2 dozen times, then this happened to the engine. IDK maybe I should count my losses and move on… It was just my first vintage outboard I fixed, so I am a little bummed about it.

Ideas?

Chad
May 9, 2023 at 9:09 am #276081
Buccaneer
Participant
US Member
Assuming you had the motor in gear while trying to turn the powerhead
via the prop? If so, perhaps the clutch dog only allows you to turn the
powerhead via the prop in the opposite direction of the gear selection?
Of course, don’t allow the driveshaft to turn the wrong direction, as
the impeller may be damaged.

Prepare to be boarded!
May 9, 2023 at 9:25 am #276083
Tubs
Participant
Is it possible that the prop
is slipping on the hub?
Tubs

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.
May 9, 2023 at 2:32 pm #276086
fleetwin
Participant
US Member
Tubs brings up a good point..Perhaps the rubber prop hub is totally shot….

Are you sure the shift linkage is connected/adjusted properly? You didn’t pull out that little phillips screw at the bottom of the gearcase did you? (Yes, I realize that the 1955 models didn’t use that pin, but perhaps someone swapped out the gearcase). If you removed that phillips screw, then the inner shift linkage fell out of position which might explain why it isn’t shifting into gear…

Finally, if you suspect the crank splines are shot, there is one further test to perform to confirm/deny this condition. Put the engine in a test tank/barrel and start it up… Does it pump water? If so, then the splines are OK because the driveshaft must be turning. If the engine does not pump water, then the crankshaft splines may be an issue.
May 9, 2023 at 7:38 pm #276100
Chad Reeves
Participant
US Member
Thank you all for your help and time. I am going to look into the hub in the prop to see if that is the problem, it very well could be, I have another prop at home I could put on the engine. As far as I know the lower unit gear case is the original, I know what you are talking about regarding the phillips screw in the lower unit and this lower unit does not have that. Though I will check again to make sure. I will look into both of these ideas when I get home from work. I’ll then try to run it in my tank and see what happens about it pumping water.

Thanks!
May 10, 2023 at 8:54 am #276114
fleetwin
Participant
US Member
OK, so there is no pivot screw. Sure hope it is just the prop hub. Are you sure the shift linkage isn’t messed up somehow above the gearcase? Those brass shift rod connectors get stripped out easily and can be a bear to install properly. How about removing the little cover over the shift rod connector, then moving the shift lever back and forth to make sure the linkage is connected and moving properly.
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