Remember the direction of the impeller vanes if any were left on when you initially lifted the housing off.
Yamaha water pump impeller direction.
If this water is not.
Be sure the o rings stay in place.
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.
Clean the water pump housing.
Apply thin coat of multipupose lube to inside of the pump cover.
Straight vane impellers function in either direction.
Learn from my mistake and check.
If your yamaha 90hp water pump has been neglected for some time it may also be necessary to replace.
Install water pump housing turn driveshaft as you place the housing on top of the impeller.
If you did not notice they were all missing or you forgot then remember that all of these motors rotate clockwise.
The rubber impeller is located inside a stainless steel cup and uses the water for lubrication.
If you do this correctly the arms of the impeller will curve to the left.
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.
Re install the water pump housing.
Exceptions are pumps with straight vane impellers vanes perpendicular to the shaft and shrouded impellers.
Rotate the drive shaft clockwise and at the same time push down on the pump cover to ease entry of the impeller into the cover.
For these reasons it s best to replace your water pump impeller or the entire water pump assembly when servicing these items and never rotate your outboard s crankshaft or driveshaft in a counterclockwise direction.
Shrouded impellers turn so they scoop the fluid.
You will turn the driveshaft clockwise for standard right hand rotation models.
Impellers must turn in a direction so that the fluid is pushed not scooped through the pump see sample drawing below.
This needs to be fixed.
But again since you will be looking at the bottom side of the water pump you will be seeing it backwards.