How to Repair the Water Pump on an Evinrude Outboard Motor

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The damage to an outboard's water pump will include glazing, like the crater glass that forms from the intense heat of a meteor strike. The pump's impeller may look like plastic left under a sunlamp. When you repair the water pump on an Evinrude outboard, remember that while water cools the motor, parts of the pump, mostly the impeller, are moving against the water, creating friction. Even though the water carries away some of the impeller's surface heat, enough lingers to destroy the pump eventually, leaving you with a pump to repair.

Remove the bolts holding the water pump to the lower unit using a socket wrench. Remove the entire pump, the large-hole gasket, the face plate and the small-hole gasket.

Remove any trace of gasket material from the water pump components, using a mild cleaning solvent, like mineral spirits, on the metal parts and isopropyl alcohol on the plastic parts. Allow the parts to air dry.

Inspect the impeller for brittle, missing or burned blades. Inspect the individual blades of the impeller for tears, cracks or other damage, including excessive wear or a glazed surface indicating melting. Replace the impeller with the one from the pump replacement kit if you see these defects.

Squeeze the vanes inward, toward the impeller hub, and release them. If they don't spring back, replace the impeller.

Slide the impeller up and down on the driveshaft; it should slide smoothly. If it seems to drag a bit, roll up a small piece of emery cloth and use it to clean the driveshaft contact surface inside the impeller hub. Replace the impeller if cleaning the inside of the impeller hub fails.

Visually inspect the inside of the water pump housing and the insert that serves as a lining for the housing. If the insert appears burned or otherwise damaged, replace the insert. Check the pump housing for any sign of wear or overheating, including melted plastic. Some wear is acceptable, but deep grooves, other than the machined groove, are unacceptable; a deep grove is one that catches when you run a fingernail over it.

Replace any grommets or seals, including the water tube grommets, that appear burned, or have brittle, cracked surfaces. Reassemble the pump. Slide the water pump down the driveshaft. Thread the bolts through the housing into the lower unit and tighten the bolts to 75 inch-pounds, using a torque wrench.


  • "Evinrude Repair Manual -- 2.5 to 250 HP Models, 2002-2007"; Seloc Marine; 2007

About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.

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