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raw water circulation

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05 V ride with a 340 monsoon.    I changed the impeller the same as most years, put the exhaust back together and started it with a garden hose shoved into the intake line as always.  after about ten minutes of running, it stopped circulating water and the exhaust was only spitting a little water.  I checked the transmission cooler and nothing blocking it.  started it again and it worked fine, ran up to temp and the thermostat opened.  I changed the oil and filter and started it again, and the water wasnt circulating again.  the impeller is pushing water through the "out line" of the pump.  something is stopping the water from flowing through the engine.  I took it to the lake and tried in the water, same thing, impeller was getting hot and not pumping water through the engine, but plenty of water pressure at the trans oil cooler.  

my last ditch effort, i hooked the garden hose upto the transmission oil cooler line and clamped it.  when i turned the water on, it ran freely and took a minute to fill the engine (it sounded empty) then started flowing out the exhaust (without the engine running).  after this i put the lines back together and put the hose back at the lake inlet line and it is flowing fine now.  

Sorry for the long post but i cant figure out what happened.  what stops the water from flowing through the engine?  I have pulled off the thermostat yet but it seemed to be working.  the thermostat is about 4 years old.

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This is why I hate fake-a-lake adapters and other home grown ways to supply the engine with water.  Not saying that' the issue, but I've never heard of an issue when using a proper flush valve when running on land.  Since you said you "shoved it in" my guess is the hose was also taking in air with the water and losing prime on the pump.  

Food for thought: your last step when you bypassed the raw water pump with the water you could have toasted the impeller by running it dry.  I'd at least pull it and inspect it, but if not for sure keep an eye on temps next time on the lake.  An overheat is far more costly than a new impeller.


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the engine wasnt running when i bypassed the impeller, but it did run dry for about a minute in the lake before i could verify it wasnt pumping.  I will check it.  the indmar manual says there are two water pumps on the engine, but only goes into detail on the raw water pump.  

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ill bet it was taking air, my pressure at this house isnt as good as other locations and it may not be feeding enough water - i like the looks of that adapter, i have to get one.  

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