Merc 500 water pump question

[TominatorNY]

I almost feel stupid asking this question! I dropped the lower unit to change the impellor. Kept everytyhing perfectly in order on the workbench to put back together..... until my son came along and started playing with the impellor. So now I don't know which direction to curve over the now impellor flaps when squeezing it into the water pump housing! Looking straight down at the lower unit from above the crankshaft, I can figure out which way is forward gear by turning the shaft and checking the prop. So the impellor blades must curve back in the opposite direction that the shaft turns, is that right?? Thanks!!

 

[MartyTn]

Re: Merc 500 water pump question

Yes, just keep in mind that the drive shaft always turns clockwise when the lower unit in it's normal operating position, so you can know that the impeller blades trail off in the other direction... When I did my first lower unit I found a spot on the bench between toolboxes where it would be almost impossible to move or knock the impeller because of saving the direction thing, and that was just to protect it from myself... Somehow I succeeded... Good luck with it.

 

[tmcalavy]

Re: Merc 500 water pump question

When I do mine I place the impeller down even with the pump housing (lower). Then I have someone rotate the driveshaft or the prop clockwise while I gently push the impeller down into the housing. This helps turn the impeller vanes back counterclockwise where they should be. Then close it up and reinstall the LU.