BOATING TIPS -- DECEMBER 1991
Impellers

If when you are "impulsive", you are "impelled", then this "was" my "impulsive" year! That's because two of my sea-water impellers crumped out during the season. And some of the after-effects of these incidents caused me to make them the subject of this month's column.

The first impeller was on my genset. It died just as we were entering Canadian waters on a trip north. I thought I had a spare in the spares box, but I was wrong. And so after about five marine operator calls to Nanaimo and Campbell River, we found one, at Lund. The cost was about triple what it would be at a discount supplier here. And that's not to mention the inconvenience of the side trip to that port, or doing without 110 volts for a day or two on the way.

Changing one of those little parts is really simple, perhaps ten minutes. The typical pump has a few screws or bolts holding a cover plate onto the side opposite the pulley or drive shaft. Take off the cover, slide out the remnants of the old impeller, squeeze the blades on the new one into a smaller circle, and slide it in (while you turn the pump shaft, if possible), put the cover back on, you're done with the fix.

But in addition (and I needed Terry Peterson at Chrysler Pete's to remind me of this) you need to find the old impeller blades which your pump "ate up", if possible! Frankly, I hadn't even thought about these little shreds of impeller, figuring they were gone, deep sixed, so to speak. WRONG.

You see, my second impeller failure came after the fall haul-out for bottom paint and zincs. After re-launching, I started up the engines and my port side was only supplying about half the normal seawater. I ran the ten minutes to my slip, and by then, no flow at all. So I changed that impeller ... this time, I did have a spare. Then I went over to Chrysler Pete's for a new spare, and that's when I got Terry's advice. So I pulled one end off the engine's heat exchanger, and discovered a virtual rogue's gallery of decadent, homeless impeller vanes. There were nine, quite a feat since a new impeller only has five! The old blades had blocked some of the tubes in my heat exchanger, so I wound up thoroughly cleaning it, too.

What's the bottom line? Simple: First, carry spare impellers, even two if you have one that fails a lot (my generator is a glutton!). Second, stick your finger up into the ends of the heat exchangers and pull out the pieces. Third, once in a while, open up your heat exchangers and check them for blockages.

By the way, one last reminder: Don't forget your engine zincs this season! Standing salt water can do its dirty work if you don't renew these little sacrificial beasties regularly.

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