Need help with water pump Force

[vintageoutboardman]

Hi everybody,
I’m currently working on a 5hp Force from about ’94. I normally only work on older OMC’s so this one is a bit different for me. What confuses me is what way the impeller should be installed. This impeller type got the keyways half way through, so only one open end. When I took out the old impeller it was installed with the open end of the keyways facing down, so you have to put it on TOP of the key in the driveshaft.
This doesn’t look right, because the water pump housing also has a keyway and you can actually push the driveshaft down enough so that the key in the driveshaft locks in the keyway of the impeller housing. That way the driveshaft can’t spin anymore, so I can imagine if that happens when the motor is running, it will blow itself up.
My thought is that the open end of the keyways in the impeller should face upwards, because than the driveshaft can’t accidentally lock in the housing. So I’m thinking it should be installed with the key of the driveshaft sliding into the keyways in the impeller from ABOVE, so the open end of the keyways in the impeller are facing up.

To make things more clear I found a picture on Marineengine that shows the the keyway in the housing and the one open end keyways in the impeller.
https://www.marineengine.com/parts/imag … 9026A1.jpg

Edit: the keyways in the impeller are exactly halfway through, so it will fit in the housing perfectly both ways, either with the open ends down or up.

Would be great if someone could help me out!

[frankr]

I’ve never been into one of those, but looking at the diagram there is a item #31 "bearing, drive shaft support". That’s all I know.

http://www.marineengine.com/parts/force … all-models

[vintageoutboardman]

Thanks for your reply! That bearing support is only for limiting the side to side movement of the driveshaft I believe. I could be wrong of course since it’s my first time working on a Force also…

[Tom]

I wish I could help more, but I can’t imagine the weight of the driveshaft is supposed to be supported by the impeller.

I think the slot in the pump body is so you can remove it without taking the driveshaft out. Is the pump body in the wrong position, allowing the pin to sink into the slot?

Is the pin easily removable?

Tom

[frankr]

I agree, it sure "seems like" the weight of the shaft should be supported by the pinion gear and not the impeller. But what do I know?

[vintageoutboardman]

quote Tom Manley:

I wish I could help more, but I can’t imagine the weight of the driveshaft is supposed to be supported by the impeller.

I think the slot in the pump body is so you can remove it without taking the driveshaft out. Is the pump body in the wrong position, allowing the pin to sink into the slot?

Is the pin easily removable?

Tom

Thanks for your reply!
The slot in the pump body surely looks it’s there so you can remove it without removing the driveshaft. That was my thought too. The pump body is in the right position for sure. If you push down on the driveshaft while turning it (clockwise) it runs down the pump body till the pin catches in the slot. I don’t know if the driveshaft would sink down on it’s own while running, but I surely don’t trust it either.
The pin is easily removable. I took everything apart and put it in an ultrasonic cleaner.

[vintageoutboardman]

quote FrankR:

I agree, it sure "seems like" the weight of the shaft should be supported by the pinion gear and not the impeller. But what do I know?

That was exactly my thought too. But it seems like pinion gear sits either too low or the driveshaft simply slides all the way through the pinion gear. I find it a strange idea too that the impeller has to support the weight of the driveshaft. Really confusing…
Is the pinion gear hollow all the way through or would there be some kind of ‘stop’ to support the driveshaft?

[Tom]

Move the shift rod so the motor is NOT in neutral. When you turn the driveshaft now, does the propeller turn?

If not, the driveshaft may not be back in the pinion gear, and drops lower than it’s supposed to.

T

[vintageoutboardman]

Tom, I think you just found out what the problem is! I can’t spin the propeller, it only turns half a turn or so and when I put it in gear and turn the driveshaft, the propeller doesn’t spin. I don’t know how the pinion gear got out of place, because it worked fine when the lower unit was still attached to the motor, but I think I must have pulled out the driveshaft too far so that the pinion gear fell out. Now I can take the whole gearcase apart. I hope I will be able to put it back together, I always try to avoid opening up gearcases…

[Tom]

"I took everything apart and put it in an ultrasonic cleaner" was the clue…

I always hesitate to remove a driveshaft from a lower unit, I’ve had to take too many apart to get the pinion lined up correctly.

Tom

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