if that motor is a true 1989 ,it would have a 3 blade impeller ,the last 2 I replaced this month ,have a cone shaped rubber grommet on top of the water pump housing that buts up against the exhaust leg (motor ) as you lift it back into place ,I know both of mine were cracked and my impellers looked good but they would not pump water until I replaced them and the rubber grommet ,otherwise if you have the copper tube ,I guess I usually blow air through them from underneath when the lower unit is removed and about 5 out of 10 the the tell tale hose coming out the side of the motor is plugged ,and I believe your plastic tapered key on the driveshaft for the impeller will only go together one way .......