The Yamaha outboard motor uses a black plastic impeller that is located in the bottom housing of the motor, underneath the water pump cover. The impeller is designed to pull water through the water pump in order to keep the engine cooled down while it is running. Occasionally, debris can get sucked into the impeller, causing damage to the part and requiring that you replace it. You can do the job yourself in about an hour and save some money.
Remove the four screws on the bottom of the Yamaha outboard motor engine housing with a screwdriver. Slide the bottom housing away from the upper housing. Locate the water pump on the top of the bottom housing.
Unfasten the four bolts that secure the water pump cover to the bottom housing, using a socket wrench. Slide the pump cover over the motor shaft to remove the part. Slide the black plastic impeller that sits just under the water pump cover off the motor shaft. Dispose of the old impeller.
Slide the new impeller down the motor shaft and position the part where the old impeller was placed. Move the water pump cover down the motor shaft and place it over the new impeller.
Attach the water pump cover to the bottom housing with bolts. Secure the bottom motor housing to the upper housing with the screws.
To avoid getting burnt, let the Yamaha Outboard Motor cool down before attempting to replace the impeller.