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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