replace mercruiser water pump impeller

The MerCruiser outdrive, or sterndrive, motor has been used on marine watercraft for decades. Like all marine engines, the MerCruiser relies heavily on its water pump impeller to send outside water through the engine manifold, jackets and passage to keep it cool. The rubber impeller inside the pump housing suffers continuous use while the engine runs, and can fail from age, wear or overheating. Replacing the water pump impeller on the outdrive requires removal of the lower unit case.


Place the engine in a half-tilt position. Remove the ignition key and disconnect the negative battery cable with a socket. Use a socket to remove the lower case oil plug and drain the gear case oil into a pan. Replace the plug and tighten it. Place the shifter in forward gear. Unscrew the anode underneath the lower unit, with an Allen wrench. Mark the trim tab position with chalk. Use an Allen wrench to unscrew the trim tab, but only loosen the screw to pull the trim tab free.

Mer Cruiser Alpha 1 water pump kits
Sign In or Register to comment.