57 QD 18 H Stuck drive shaft

[MTguy63]

My 15 year old son bought a boat last week with a 57 or 58 Seahorse 10hp. It looks like the water pump isn't working, which doesn't look too surprising. When we tried to take the lower unit of, the drive shaft will not come out - it only lets the LU come down an inch or two. I assume it's the pin catching on the impeller housing that is preventing the lower unit from coming off. I saw some information on here about stick drive shaft, but we can't really get to it since the lower unit won't come off. I'm not sure I can get vice grips on the shaft with the small Gap I have, or even if I can get WD40 to the shaft. Can we take the lower portion of and get to it from there, and if so, what are the chances we can get the drive shaft to release?

Do I have to take the powerhead off? If so, now what am I changing - it looks like at least a gasket? I was excited to have this old motor, but now this water pump issue is changing my mind.

Thanks.

 

[F_R]

Can we assume the shift rod is disconnected? If so, go ahead and force the lower unit off by brute force. The impeller pin will break through the pump housing with no serious damage. Then you can deal with the stuck drive shaft splines.

All because somebody left out a 10 cent o-ring.

 

[MTguy63]

Good point about the shift rod - yes we disconnected that. I was really hoping to avoid breaking that impeller housing, if I haven't already.

Okay, the o-ring comment has me confused. I haven't looked into this enough to see where there will be an o-ring involved. I thought it was due to a lack of lube when assembling the drive shaft.

 

[hardwater fisherman]

Just below the splines at the top of the driveshaft is a groove for an O ring...If left out or damaged water can cause the driveshaft to stick in the crankshaft.. If so you really dont have much choice but to force them apart.

 

[F_R]

There is an o-ring groove around the top end of the drive shaft. The o-ring keeps grease in and water out of the splines. Omit it and the result is rusted splines.

I've forced the pin through the pump housing quite a few times. In fact, if not possible to get the shaft out of the splines, I've widened the resulting groove a bit and put it back together the same way it came apart. Understand that was a last-ditch effort. Give it long enough time and the splines will completely rust away out of the crank. That is terminal.

 

[MTguy63]

So the pump will work with an extra slot in the top housing?

Right now, we are trying to be creative at getting the screws out of the pump housing do the lower unit will come off. If we are successful at that though, the drive shaft had better come off, or I don't know how well get it back together. I guess if I get it all out, I can Dremel a slot in the top housing if it works that way.

I'm a little surprised that it would be do rusted at the top, after looking at the gear box, though. When we drained it we got about 4 oz of water, and for drops of oil, but everything in there looked pretty clean still. Maybe we have dissimilar metals up top that promote corrosion?

If it comes down to pulling the power head, how ugly will that be? So far, it's not a bad learning experience for the 15 yr old, but I don't want it to get too ugly.

 

[F_R]

Let's back up. In your first post you said it will drop down an inch or two. That is way more than the pump pin will allow. So I don't know what to say about that.

You probably know by now that dis-assembling the gearcase is futile.

I must say I've never attempted to get the screws out of the pump housing. I wish you luck.

I can testify that it will work with a slot in the pump housing. If you choose to go that way, simply assemble the pump back to how it looked when you pulled it out. You will have to finagle it a bit to get the pin aligned with the slot when reassembling.

I guess I'm numbed by being a salt water guy. Believe me, I've seen lots of rust problems up there. In fact, water entering the lower crankshaft bearing is the #1 killer of salt water motors. The crankshaft is steel, sticking down into a nasty environment. Drive shaft is stainless, not a problem.

Kind of odd that a guy would be comfortable with tearing a gearcase apart but fears pulling a powerhead. But I understand, I suppose. The only difficult part is the screws if they are seized. A hand impact screwdriver is a godsend there.

EDIT: You do understand that if you can't get the lower unit off, you can't get the powerhead off either, right? Something has to give, be it the pump pin or splines.

 

[MTguy63]

Yes, the inch or two comment cane from my impression after turning the assembly to widen the gap. 1/4" is more like the distance it came down.

Yes the gearcase didn't help with the crankshaft issue, but I was able to pound on the end of the shaft a bit too try to loosen it up. Seeing that there were only about four drops of lube in there, and that we need to replace an o-ring, along with the learning experience were good though.

The gearcase seemed straightforward. The top end looks scarier to me, but I'm ignorant about ALL of it. No, I did not realize that the powerhead was going to be just as hard to get off. I was assuming there would be something else to take apart up there. I guess that's good insight.

Trying to access the screws did not work. Nothing quite flexible enough. We may try inverting and trying to get something in to loosen things up before pulling the pin through the housing.

Thanks for all the advice and insight.

 

[racerone]

I have lots of those pump housings.-----You may not have them.-------I would cut the pump housing / screws with a hack saw.-----Then remove lower unit and pump housing.----Make adapter / clamping fixture to pull driveshaft out with a slide hammer.----Done.

 

[lindy46]

You can try inverting the motor and spray penetrating oil down (up) the driveshaft to soak the junction with the crank. May take some time to work. Hang motor from the lower unit and put a pillow underneath. If the rust isn't too severe, this may work.