Changing a water-pump impeller is normally a straightforward job that every boater should be able to tackle. Impeller pumps
are far more common than you might
imagine and are used for everything
aboard from bilge and shower pumps
to freshwater and seawater washdowns.
Generally, they can be relied upon to
work without incident for many months
or even years, but that doesn’t mean
they’re maintenance free.
One of the most important of these
pumps is for raw-water cooling on an
inboard engine. Should this pump fail or
work at less-than-full capacity, overheat-
Water-pump impeller service
If cooling water is the lifeblood of the engine, the impeller is its heart. A regular
checkup of the water pump is just what the doctor ordered
If the inside of the cover plate shows wear, try reversing it,
as most are symmetrical. Clean off any paint, and polish
the plate with fine sandpaper before refitting. This can help
extend the life of the pump by several years.
A selection of
common raw-water pumps.
From left: a
Jabsco spindle-driven pump
from a Perkins
engine, a Volvo
model, and a
Johnson gear-driven pump.
All can be serviced in the
in this article.
I rate this
project as easy to moderate
You’ll need an impeller and
I used channel lock
pliers, screwdrivers, wrenches,
clean rags, and glycerin
This project will take
approximately 1 to 2 hours
Your only cost will
likely be the price of a replace-
ment impeller. Prices vary
depending on the size and type
of your pump
YOU GOT THIS!
DO IT YOURSELF
ARTICLE & PHOTOS BY MARK CORKE
ing may result, causing damage to the
engine. It’s a great idea to get into the
habit of looking at the exhaust outlet
after starting the engine to make sure
water is flowing. All engines differ, but
if you make a quick visual check each
time the engine is fired up, you’ll be
more likely to quickly spot something
amiss: Reduced water flow, excessive
steam, or a dry, throaty exhaust note is
a sure sign that something isn’t working
as it should.
I like to change my raw-water impeller every winter no matter how little I
may have used the boat during the season. This is largely a preventive mainte-