How to Replace the Water Pump on a Yamaha Outboard Motor

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The water pump on your Yamaha Outboard Motor has a special seal over the trim tab that you need to remove in order to access the bolts that hold the water pump in place. Replacing the water pump will take you about an hour to complete. The Yamaha motor water pump needs to be replaced about once a year to be maintained properly for the motor to run efficiently. You can purchase a kit that will allow you to repair the existing water pump or simply replace the old one.

Items you will need

  • Water pump rebuild kit for yamaha outboard motor

  • Screwdriver

  • Socket wrench set

Remove the hose from the water pump outlet by undoing the clamp with a screwdriver and sliding the clamp up the hose. Slide the hose away from the outlet valve.

Undo the clips that are underneath the trim tab of the lower cowling of your Yamaha Outboard Motor and slide the lower cowling away from the upper cowling, being careful to slide out the motor and shifting shafts inside the cowling as well.

Detach the black plastic cover that is located over the trim tab with a socket wrench so you can access the bolts that will let you remove the water pump.

Unbolt the cover of the water pump by using a socket wrench to remove the 6 bolts that are holding the cover in place. You will find the cover on top of the lower cowling, surrounding the motor shaft. When the water pump is detached, lift it over the motor shaft to remove it from the motor.

Inspect the impeller on the inside of the water pump for any signs of damage or debris. Take the stainless steel gaskets off of the lower cowling and clean any debris from the area.

Lower the new stainless steel gaskets on to the lower cowling of the Yamaha outboard motor and place the new water pump on top of the cowling by lowering pump down over the motor shaft and placing it in position over the mounting bolts.

Reattach the nuts over the mounting bolts of the water pump and tighten them with a socket wrench. Place the plastic cover over the top of the bolts and reattach with a mounting bolt.

Slide the motor and shifting shafts back inside the upper engine cowling and then connect the two pieces of the motor together until the trim tabs are joined.

Use the clips under the lower trim tab to connect the two pieces. Reattach the hose to the water pump outlet with a screwdriver and reposition the motor onto the boat.


  • When removing the water pump, be careful not to damage or scratch the motor shaft.