Topic: 1951 Johnson QD12 lower unit won’t drop – Antique Outboard Motor Club,Inc

This topic has 20 replies, 10 voices, and was last updated 6 years, 4 months ago by fleetwin.

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December 8, 2017 at 11:30 pm #8820
bob-d
Participant
US Member
Ok so I have the two covers off the lower unit and the top jam nut off the C shift rod connector. Have also removed the 4 main bolts holding the lower unit.
Lower unit drops down about 1" and they gets hung up on something metal. Can move up and down, and it’s banging into something. Do you have to remove the powerhead to get the lower unit off on this model?
What am I missing?
Thanks,
Bob D
December 8, 2017 at 11:55 pm #68413
crosbyman
Participant
Canada Member - 2 Years
http://www.youtube.com/watch?v=SVOedhzPP7M

try this

Joining AOMCI has priviledges 🙂
December 9, 2017 at 12:36 am #68415
amuller
Participant
I”m not familiar with this motor. Is the shift rod really disconnected, or just a jam nut loosened? It kinda sounds to me as if it isn’t, because if the drive shaft were stuck in the crank it probably wouldn’t drop much at all.
December 9, 2017 at 1:05 am #68416
bob-d
Participant
US Member
Amuller, shift rod totally disconnected.
This is weird.

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December 9, 2017 at 2:50 am #68420
bob-d
Participant
US Member
Ok so I used some force and it came off!
Problem was driveshaft was rusted to crank. The driveshaft stayed up in the housing, and the lower unit dropped down. Pulled powerhead off with the driveshaft connected. Any tips to separate? Have it soaking in PB Blaster.
Thanks,
Bob D
December 9, 2017 at 12:09 pm #68423
fisherman6
Participant
US Member - 2 Years
PB Blaster is a good place to start. Patience and some gentle heat to help the penetrant to flow into the joint might help. This drive shaft has the fine spline into the crankshaft, so it could be an adventure getting it out depending on how rusted the connection is. Try working the driveshaft back and forth and in a circular motion so any slight movement will open the joint up for the penetrant to enter. With enough working it around, it should eventually work free. Others may have more suggestions. You can always try the 50/50 acetone/ATF mixture if the PB Balster doesn’t cut it.
-Ben

OldJohnnyRude on YouTube
December 9, 2017 at 1:07 pm #68424
fleetwin
Participant
US Member - 2 Years
Be sure to avoid the temptation to clamp vice grips (or similar tool) to the lower portion of the driveshaft for pulling/yanking, etc. Grabbing the driveshaft in this area will destroy the seal and bushing surfaces on the driveshaft leaving it useless. It is best to pull the powerhead/driveshaft off the exhaust housing if "gentle persuasion" wont release the driveshaft.
Once off, you can clamp the upper part of the driveshaft and attack it with an air hammer to loosen up the splines.
December 9, 2017 at 3:39 pm #68429
bob-d
Participant
US Member
Thanks Ben and Fleetwin. Have it hanging upside down now from a vice with the shaft protected with soft jaw adapters. In addition to the PB , I am also shooting it with Aero Kroll, which is also suppose to be good. Next step would be the 50/50 acetone ATF mixture.
Fleetwin I have an air hammer. Where do you hit it, and what tip do you use?
Thanks,
Bob D
December 9, 2017 at 6:18 pm #68434
fleetwin
Participant
US Member - 2 Years
Well, I would clamp the upper part of the driveshaft in vise (doesn’t matter if you hurt this surface) with the powerhead hanging down (have something a inch or so from the top of the powerhead so it doesn’t crash to the floor). Then, I would use a flat (maybe a convex/concave tip don’t know which one is which) ended tip on the air hammer to rap on the upper driveshaft close to the powerhead. It might help to have an assistant with some sort of rig to pry down on the powerhead while rapping on the driveshaft with the air hammer.
December 9, 2017 at 10:41 pm #68443
bob-d
Participant
US Member
Thanks Don, will give this method a shot. Don’t have a tip for my air hammer that looks like that. Will have to get the grinder out and improvise.
Bob
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