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A Few Tips for Easier Raw Water Pump Impeller Changing
by Tom Neale

This is a continuation of Tom's Tips from his section of the web site. Go to his section there for many more tips on this subject and others.

1. If you’re trying to squeeze the blades of a new impeller to make it go inside the raw water pump, and you can’t depress the blades sufficiently with your bare hands to get it into the pump, try this trick. Get a good quality hose clamp which doesn’t have perforations that can tear the blades and which has rounded edges so as be less likely to cut the blades. The clamp must be of sufficient diameter to fit over the impeller. Put it around the impeller and begin tightening down. You’ll have to find an area on the impeller that’s close enough to the center of the impeller to sufficiently depress the blades, yet sufficiently out from the middle so that the impeller can be pushed into the pump far enough to get onto the shaft. This may take some trial and error. As you tighten down on the hose clamp, make sure that the blades deflect in the right direction for the rotation. Don’t over tighten and take care not to damage the blades. The blades will still be extended enough so that you’ll have to push and rotate, but it shouldn’t require quite as much muscle. When the impeller is in deeply enough so that it’s mated with the shaft, loosen the hose clamp with a screw driver and slide it off the impeller. If you haven’t gotten the impeller in far enough, it may pop back out of the shaft. Hose clamps and other equipment can cut. Be careful.

2. Before you start your engine, you will, of course, have opened the raw water through hull valve that you closed prior to the job. If your engine or its pump is below the water line (and there is no higher loop between the through hull and the pump) let it sit a few minutes so that sea water will find its way to the pump. This will help provide a well lubed start up, thus lessening the chances of damage to the blades from dry running.

3. Disable your engine from starting (as by unhooking the battery) before you work on it.

Copyright 2005
Tom Neale


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