How often should you replace the raw water impeller?

jon711 said:
I have heard in the past, that a neoprene impeller if soaked in hot water for a few months will lose the vane set, but have no proof that it works. I would guess that that would not work with nitrile. The difference in the Jabsco part numbers, Neoprene is xxxx-0001b and nitrile is xxxx-0003b.

Good luck

Jon
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How would you keep the water hot for a few months?
 
Not sure, guess you just keep it on simmer. It's only something a few customers said to me when I worked at Jabsco. As I said, though, I did not see the impellers after, so have no proof. But may be worth a go - nothing to loose!

Jon
 
jon711 said:
I have heard in the past, that a neoprene impeller if soaked in hot water for a few months will lose the vane set, but have no proof that it works. I would guess that that would not work with nitrile. The difference in the Jabsco part numbers, Neoprene is xxxx-0001b and nitrile is xxxx-0003b.

Good luck

Jon
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take it out & re install @180 deg so in effect is runs the other way
 
sailorman said:
take it out & re install @180 deg so in effect is runs the other way
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Can't do that with all impellers some have a half keyway, some are splined, but, I would be dubious, as bending it the other way, may weaken it, then you just end up sending broken vanes into the heat exchanger. The same may apply with the hot water method, but not sure...

Jon
 
jon711 said:
I have heard in the past, that a neoprene impeller if soaked in hot water for a few months will lose the vane set, but have no proof that it works. I would guess that that would not work with nitrile. The difference in the Jabsco part numbers, Neoprene is xxxx-0001b and nitrile is xxxx-0003b.

Good luck

Jon
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Hi .. Thanks good information - didn't realise there were different material available. I changed my impeller after 5 years and the replacement failed after 6 months. I put the original back in and still running. I suspect the original was neoprene as it is softer and a little more flexible. The failed one was a lot more "brittle" with 4 splines having failed. Still have 2 new spares that I will check. Any opinions or preference on which is better??
 
The Jabsco neoprene impellers are black, the nitrile ones are brownish...The nitrile ones are really designed for bilge pumping, as they are more resistant to diesel infected water. But, if you are in. Polluted water, you may find nitrile a better bet....

Jon
 
If you use the engine quite a lot it's prudent to replace after 2 years. But when removing it check the base of each blade that there are no fine cracks indicating impending failure - if still good, stick it in the spares locker. Even if one blade is looking dodgy, you can take it out with a knife and retain the impeller for that rainy day, but not rely on it long term, I suggest


PWG
 
jon711 said:
I have heard in the past, that a neoprene impeller if soaked in hot water for a few months will lose the vane set, but have no proof that it works.
Jon
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They mean a few minutes. I take out mine at the end of the season and pop it into boiling water, when it immediately springs back to shape. After thorough inspection I've not yet seen a fault in 8 years of alternating between two impellers, but we only motor for a few 100 hours a year. With a previous engine I had an impeller fail while motoring in heavy weather and fitting the spare was very fiddly. I've fitted a Speedseal pump cover to make it quick and easy to replace - http://www.speedseal.com/saferboatindex.html
 
dutyhog said:
They mean a few minutes. I take out mine at the end of the season and pop it into boiling water, when it immediately springs back to shape. After thorough inspection I've not yet seen a fault in 8 years of alternating between two impellers, but we only motor for a few 100 hours a year. With a previous engine I had an impeller fail while motoring in heavy weather and fitting the spare was very fiddly. I've fitted a Speedseal pump cover to make it quick and easy to replace - http://www.speedseal.com/saferboatindex.html
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We too have a Speedseal. (Although I tend to tighten the so called 'hand tighten screws' up with a pair of pliers.)

I used to replace the impeller every year. Nowadays I usually just remove it and inspect it and stick it back in. We carry several spare ones though. I get generous so engines and give it a new impeller. Otherwise I ended up with lots of 'old' impellers that were perfectly ok.

I've only had one fail a couple of times on the dozens of boats I have sailed or owned. My feeling is that it would be a very poor heat exchanger that was blocked up to the point of making the engine overheat with a couple of impeller blades. You shouldn't leave them there of course but in an emergency I would probably be leaving the dismantling of the heat exchanger and hoiking out the bits of impellor blade until the emergency was over or it proved necessary because the engine was actually overheating. Having said that its only three jubilee clips to gain access to the end of the heat exchanger stack on our engine.
 
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john_morris_uk said:
We too have a Speedseal....My feeling is that it would be a very poor heat exchanger that was blocked up to the point of making the engine overheat with a couple of impeller blades...
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Just about to order a SpeedSeal Life, thanks all for the reminder.

I have a vague memory of losing a blade in the past, would back-flushing remove it?
 
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