Replacing An Outboard's Water Pump

[Hot Rod Johnson]

Replacing An Outboard's Water Pump

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Story And Photos By John Tiger
Published: Fall 2013

Don't be put off by the fact that you have to drop the lower unit. Here are some tips to get you through it.



1. Dropping the gearcase to access the water pump requires removal of the mounting bolts.

Outboard water pumps are simple designs. Located just atop the lower gearcase assembly, they're easy to access and service, too. The pump houses a rubber impeller that's keyed to the engine driveshaft. Water enters the lower gearcase through inlets on the sides of the gearcase, just above the propeller shaft area. The driveshaft turns the pump inside a plastic housing with a stainless steel liner. The pump draws water through the intakes and up into the housing. The impeller blades (vanes) touch the liner at lower speeds as the driveshaft turns, but as the engine revs up, the impeller blades bend back away from the housing liner. The pump sends water out of the top of the housing through a brass tube, typically about a half-inch in diameter, up to the engine's powerhead, where it circulates through the system's cooling passages.

Salt, sand, mud, sticks, and other debris take their toll on the pump impeller, housing, and related parts. That's why most outboard technicians recommend replacement every season, or at worst every other season. There are legions of stories that go "I've had my outboard for twenty years and never replaced the water pump"; however, good preventative maintenance practice includes replacement of the pump and housing at regular intervals.


http://www.boatus.com/magazine/trail...water-pump.asp

[Dschouest42]

Thanks for this! I might need to change the water pump on this old boat I am working on. Ill find out if its not "ticking" out the little spout when I get her hooked up

[Hot Rod Johnson]

Glad that the information may help you with your boat maintenance. Once you change the water impeller out, the next time will be a breeze. Any thing that I can do to help please let me know..

[Jbower]

Don't forget the shift shaft. A lot of them need to be disconnected usually under the carbs or intake depending on model. Some of them disconnect just about the lower unit and some don't need disconnected at all. And upon reassembly make sure the water tube goes in the hole easily I have seen a few of these damaged due to someone not paying attention