Impellers must turn in a direction so that the fluid is pushed not scooped through the pump see sample drawing below.
Yamaha water pump impeller direction.
Shrouded impellers turn so they scoop the fluid.
Remember the direction of the impeller vanes if any were left on when you initially lifted the housing off.
If you do this correctly the arms of the impeller will curve to the left.
Install water pump housing turn driveshaft as you place the housing on top of the impeller.
Re install the water pump housing.
If this water is not.
While trying to get this on i flipped the impeller.
This needs to be fixed.
You will turn the driveshaft clockwise for standard right hand rotation models.
Clean the water pump housing.
I need to take it apart and turn it clockwise.
Learn from my mistake and check.
If you did not notice they were all missing or you forgot then remember that all of these motors rotate clockwise.
Apply thin coat of multipupose lube to inside of the pump cover.
If your yamaha 90hp water pump has been neglected for some time it may also be necessary to replace.
The rubber impeller is located inside a stainless steel cup and uses the water for lubrication.
Exceptions are pumps with straight vane impellers vanes perpendicular to the shaft and shrouded impellers.
But again since you will be looking at the bottom side of the water pump you will be seeing it backwards.
As you slide the housing down rotate the driveshaft to align the impeller housing with the pump housing until it slides all the way down over the dowel pins.
Slide the assembled water pump down over the diveshaft and water pump studs.
We recommend you buy the complete yamaha water pump repair kit as it includes the various gaskets o rings and other parts that usually need replacing when you repair the water pump it s much cheaper to buy the complete kit than it is to buy the impeller gaskets and o rings separately.
Straight vane impellers function in either direction.
I applied some grease to the slots for the o rings to help hold them in place.