sludgeguy68
Petty Officer 2nd Class
- Joined
- Jul 16, 2010
- Messages
- 111
Here's the story: I picked up a non-running 15012 15 hp and wanted to restore it. I manage to get it running with the help of a donor motor, serial plate was also 15012 -from this I used mainly the flywheel, high speed needle, exhaust leg (the one I had was cracked), gear case, and other small parts. I did not use the gears from the donor motor since the forward bushing was stuck on and it all looked pretty gunky. I cannot remember if I used the drive shaft from the donor motor.
Got it running nice and smooth, low idle, pumped water... sucked a lot of gas but worked great. After a few outings it slowly developed a miss that got worse. Assuming an electrical issue, I saw the new spark plug wires were being chewed by the flywheel (I tucked them in behind the throttle control arm, which apparently pushed them up into the flywheel at WOT). The wire wasn't exposed though, so thinking there might be some other issue I popped the flywheel off again to take a look and found that the insulation on my brand new coil (ground?) wires were being just slightly shaven off. Put some liquid electric tape on it and really tucked the wires in close to the coil in this time (and thoroughly cleaned the whole plate while I was in there), re-gap points, done.
Ran good in the barrel. Took it on the boat and it felt like I hit a something while at very slow speed (which happens a bit in my part of the river, so I didn't think much of it). It soon started running terrible - popped it in neutral, messed with the mixture screws, then when I put in drive, it quit. Did the same thing once more - it would run ok in neutral then quit when shifted. I then noticed the prop wouldn't turn the flywheel at all in forward, and there was a grinding sound when I turned the prop in forward. Took off the leg and this is what I found:
Driveshaft snapped at the impeller - to me it looks like the key might've worked it's way loose and ground out a groove in the shaft? It didn't seem loose when I put the impeller on (the water pump was not new, since it looked brand surprisingly decent in the original motor I bought)
The scored impeller:
O-ring at the top of the drive shaft was torn up as well.
The prop shaft pin was almost sheared as well - this might've been from a previous underwater obstruction I'm guessing, but it's worth noting I suppose.
Now there seemed to be some very slight differences in some parts with the running motor vs donor motor. Drive shaft splines matched fine, but seemed to be machined a little longer in one of them - the one on the left is the one that split
and upper gear case shaped a bit differently (donor motor on right, the gear case I was using)
I didn't think much of it at the time since I thought most things would be pretty compatible, but now I'm carefully examining the differences. One big possible issue was the reverse gear - the one I was using at the time was slightly shorter than the donor motor. Since I used the donor motor's gear case this might have been a problem, but I don't know if it explains the drive shaft failure...
I already put the donor motor's gears and prop shaft back in their original gear case housing. Planning to use the intact drive shaft I have with a new water pump kit and o-ring, but I'm trying to prevent something like this from happening again, and would like to nail down the exact cause. I'm also hoping I didn't mess anything up in the crankcase (compression is still good at 105 psi even)
Could the wrong impeller and key really split a drive shaft like that? It seemed to be pumping water great all along so I had no idea there was a problem there.
Got it running nice and smooth, low idle, pumped water... sucked a lot of gas but worked great. After a few outings it slowly developed a miss that got worse. Assuming an electrical issue, I saw the new spark plug wires were being chewed by the flywheel (I tucked them in behind the throttle control arm, which apparently pushed them up into the flywheel at WOT). The wire wasn't exposed though, so thinking there might be some other issue I popped the flywheel off again to take a look and found that the insulation on my brand new coil (ground?) wires were being just slightly shaven off. Put some liquid electric tape on it and really tucked the wires in close to the coil in this time (and thoroughly cleaned the whole plate while I was in there), re-gap points, done.
Ran good in the barrel. Took it on the boat and it felt like I hit a something while at very slow speed (which happens a bit in my part of the river, so I didn't think much of it). It soon started running terrible - popped it in neutral, messed with the mixture screws, then when I put in drive, it quit. Did the same thing once more - it would run ok in neutral then quit when shifted. I then noticed the prop wouldn't turn the flywheel at all in forward, and there was a grinding sound when I turned the prop in forward. Took off the leg and this is what I found:
Driveshaft snapped at the impeller - to me it looks like the key might've worked it's way loose and ground out a groove in the shaft? It didn't seem loose when I put the impeller on (the water pump was not new, since it looked brand surprisingly decent in the original motor I bought)
The scored impeller:
O-ring at the top of the drive shaft was torn up as well.
The prop shaft pin was almost sheared as well - this might've been from a previous underwater obstruction I'm guessing, but it's worth noting I suppose.
Now there seemed to be some very slight differences in some parts with the running motor vs donor motor. Drive shaft splines matched fine, but seemed to be machined a little longer in one of them - the one on the left is the one that split
and upper gear case shaped a bit differently (donor motor on right, the gear case I was using)
I didn't think much of it at the time since I thought most things would be pretty compatible, but now I'm carefully examining the differences. One big possible issue was the reverse gear - the one I was using at the time was slightly shorter than the donor motor. Since I used the donor motor's gear case this might have been a problem, but I don't know if it explains the drive shaft failure...
I already put the donor motor's gears and prop shaft back in their original gear case housing. Planning to use the intact drive shaft I have with a new water pump kit and o-ring, but I'm trying to prevent something like this from happening again, and would like to nail down the exact cause. I'm also hoping I didn't mess anything up in the crankcase (compression is still good at 105 psi even)
Could the wrong impeller and key really split a drive shaft like that? It seemed to be pumping water great all along so I had no idea there was a problem there.
