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Old 10-05-2014, 08:59 AM   #41
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I think outboards and some I/O models have seawater pressure guages installed..may work..they aren't too much money and are pretty easy to install.
Hmm. Now that might just work, thanks! My last boat actually had a water pressure display on the engine computer monitor, but I never really know what it was telling me.

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Why not just change the impeller every 200 hours or annially like your manual says and don't worry about it?
A good point to include here for the record. But I've actually changed them FOUR times in the past two seasons, so that's not really the answer. Only once did it make any difference. The overpriced aftermarket "run dry" high-tech impeller I bought, thinking I wouldn't have to worry about it all season, turned out to be a dud and actually CAUSED a near-overheat once.

As with the other times (not related to impeller failure), I detected the problem by climbing down on the swim platform to check the coolant flow visually. Very effective but not very convenient.
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Old 10-05-2014, 09:16 AM   #42
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Needing to change an impeller often, i.e. short hours or time, is an indication something is wrong. Is the sea water draining out of the pump between uses? Is the flow to the pump restricted? Is the pump itself out of whack (technical term)?
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Old 10-05-2014, 10:39 AM   #43
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Needing to change an impeller often, i.e. short hours or time, is an indication something is wrong. Is the sea water draining out of the pump between uses? Is the flow to the pump restricted? Is the pump itself out of whack (technical term)?
I never said I needed to change it often. Every time I had to diagnose a problem, I checked the impeller first. Once apart, I figured I'd change it just so I don't have to worry the rest of the season. I actually introduced a problem one time because I installed what was advertised as a "better" impeller. It wasn't.
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Old 10-05-2014, 12:04 PM   #44
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I changed a couple of impellers for a friend a couple weeks back and even though he double checked with the replacement provider, he looked it over and compared it with the old one, I looked it over and we installed it.

Of course it smoked and a second time we looked it over and tried it again.....

The only difference in the old and new impellers...was the inner cutout right around the shaft....it was just a 1/8 of an inch or so different...hard to see without knowing it, but it was hanging up and making the plate just a little too snug which was what was the real alert....but it wasn't so snug that it was way different from other impellers I replaced.

The real problem was that the tiny gap on the inside was enough that it wouldn't self prime....

The funny thing was the owner was just replacing these as a precaution to his upcoming sea trial. The original impeller for this genset had a few chewed up ends of fins and one totally missing. He was like wow....but it actually was pumping and cooling fine. We put it back in and the boat passed the sea trial...but he did mention the old impeller to the new owner.
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Old 10-15-2014, 11:55 AM   #45
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I didn't see any obvious signs of impeller wear. But one good sign that the genny was getting warm was the exhaust starting to steam. It would run for an hour or two and then shut down. Obviously due to overheating. I did check it with a pyrometer but I really didn't see anything hot. All in the 150-160 range. But clearly the new impeller does pump more water.
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Old 10-15-2014, 03:07 PM   #46
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I didn't see any obvious signs of impeller wear. But one good sign that the genny was getting warm was the exhaust starting to steam. It would run for an hour or two and then shut down. Obviously due to overheating. I did check it with a pyrometer but I really didn't see anything hot. All in the 150-160 range. But clearly the new impeller does pump more water.
I'm not familiar with your model, but you may consider checking your heat exchanger for buildup.
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Old 10-15-2014, 04:53 PM   #47
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7KW Gas 3 banger Westerbeak
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Old 10-15-2014, 05:54 PM   #48
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7KW Gas 3 banger Westerbeak
Like I said, I am unfamiliar with your westebeke, but I removed my heat exchanger a few months ago and lots of the cooling tubes were clogged restricting flow and subsequently cooling of the antifreeze. If you are unaware of the last time it was cleaned, its time to do it. Your manual should say where it is and how to access it. Hopefully they made it easy to access.
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