The Rotorway mechanical
waterpump seal is prone to begin leaking when it is least convenient.
Some ships go years with no leaks and others need the water pump
seal replaced after only a few hours.
Below is a tutorial on
an easy way to replace the water pump seal while the water pump
remains on the helicopter. I have used this method many times
with great success.
First you will need to
tip the ship back with the wheels on and resting on the stinger.
Attach a drain tube to the rear radiator pet cock. Open up the
rear radiator pet cock and the surge tank vent to drain as much
antifreeze as will flow out into a clean container, this is usually
enough. The antifreeze can be reused.
Loosen the hose clamp
from the pump outlet hose so that the lower housing can slide
out of the hose.
Remove the bolts from
the top of the water pump housing. The water pump halves can then
be separated with the use of a putty knife. If gasket tears, you
will need to replace it.
Slide the housing off
the outlet hose.
I tie the lower pump
housing forward to get it out of the way while I am working.
The water pump impeller is removed
by tapping it in the direction of rotation so that it will unscrew
from the threaded shaft. The photo shows the proper direction
to tap it for removal.
A few good taps and the impeller
will break free and easily uncrew. Be sure to use wood or some
other soft material against the impeller so as not to damage it.
Note the position of the lower portion of the pump shaft seal
on the upper surface of the impeller. The new seal will install
in the same orientation.
The upper portion of the water
pump seal is removed by tapping it down from the top, It will
slide down the shaft once it is loose. Note the height difference
between the top of the upper seal and the pump casting. This will
be the same clearance when you install the new seal.
The upper water pump seal is
removed and shown in the same orientation as when installed. My
helpers ring finger is resting on the seal surface that you cannot
touch on the new seal.
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