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post #1 of 5 Old 11-19-2010 Thread Starter
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Yanmar 2GM20F, raw water pump

When winterizing my Yanmar 2GM20F, I have usually detached the intake hose from the raw water pump, attached a new hose leading to a bucket of antifreeze(on the cabin sole, at approximately the same height as the pump) and winterized the raw water side. This year, however, while the pump sucked up raw water properly, it would not lift the antifreeze from its bucket. Last year the same thing happened and was easily solved with a new impeller, but that didn't work this year.
My plan now is to double check my impeller installation and try a new, extremely carefull measured intake hose.
Could this be caused by any other problems in the cooling system - clogged intercooler, exhaust elbow,etc???
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post #2 of 5 Old 11-19-2010
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Could be wear in the pump housing not allowing a tight seal on the sides of the impeller. Look for scoring on the inside of the cover. Sometimes filing the cover smooth will fix the problem. Some covers can be "flipped" to use the smooth outer surface inside.
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post #3 of 5 Old 11-19-2010
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Try putting the bucket in the cockpit and using a longer hose.

Stu Jackson, Catalina 34, 1986, M25 engine, Rocna 10 (22#), Maple Bay, BC, Canada
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post #4 of 5 Old 11-20-2010
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Along the same thoughts as Stu .... the pump may have developed a bit of 'bypass' and therefore cant develop enough 'suction' to prime itself ... this loss of 'prime' wont happen when the hose isnt removed so that air cant enter the pump.
Rx: -- So, attach the hose to the pump, hold the open end of the hose HIGHER than the pump and completely fill the hose with water, etc. when the hose is totally filled, HOLD YOUR THUMB over the open end and then QUICKLY put the open end of the hose into the bucket and then start the engine, etc. The 'priming method' as outlined above should allow you to suck in all the AF you need.
Another poster recommended for you to check the side clearances of the pump body plate vs. impeller, etc. .... do so when you get a chance.

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post #5 of 5 Old 11-20-2010 Thread Starter
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Problem Solved. Thank you.

We raised the bucket to about two feet above the intake (set it on the quarter berth), filled the hose with antifreeze, put my thumb over it and, simultaneously, started the engine and put the hose in the bucket of antifreeze. Worked perfectly. Why didn't we think of that? Thank you.
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