How to Install an Outboard Motors 40 Hp Water Pump

Written by denise sullivan
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How to Install an Outboard Motors 40 Hp Water Pump
Install a new water pump to keep your 40hp outboard motor cool. (Jupiterimages/ Images)

As your 40-hp outboard motor runs, heat builds up inside the engine compartment. To cool the engine off, the water pump also runs continuously to draw water into the compartment. This constant motion wears the water pump down faster than the other components of the motor. Fortunately, most 40-hp outboard motors are designed to permit easy removal and replacement of the water pump.

Skill level:
Moderately Challenging

Things you need

  • Water pump
  • Adjustable wrench
  • Engine vice
  • Scrub brush
  • Engine oil

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  1. 1

    Place the transmission in neutral and remove the mounting bolts that attach the outboard motor to the boat's engine housing. On some 40-hp outboard motors, the mounting bolts are located under the engine's gear case.

  2. 2

    Slide the lower housing of the motor away from the upper housing. The lower housing is the area of the motor with the propeller. Remove the wiring harness from the lower half of the outboard motor. Use an engine vice to secure the lower section of the motor while you loosen the bolts on the water pump housing. Set the bolts and housing aside for later use.

  3. 3

    Pull the impeller and sprocket off the driveshaft. Pull out the old gaskets and clean off the inside of the housing with a wire scrub brush. Lubricate the gaskets for your new water pump with a light layer of engine oil. Slide the gaskets onto the driveshaft according to the instructions in your owner's manual.

  4. 4

    Place the sprocket and impeller on the driveshaft and replace the pump housing. Push on the pump housing and rotate the driveshaft until you feel it lock in place. Place the lower engine housing on the motor and tighten the retaining bolts.

  5. 5

    Release the engine vise's clamp and remove the lower section of the outboard motor. Push the lower section back into its original position inside the upper motor housing. Connect the electrical wiring and tighten the retaining bolts to secure the two sections of the outboard. Set the motor back in the engine housing and tighten the mounting bolts. Replace the gear case if you removed it in the first step.

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