Yanmar water pump question

Ted

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Oct 30, 2011

On a Yanmar 2GM (raw water cooled) and 2GMF (fresh water cooled) are the raw water cooling pumps identical for these two motors? They look the same from the outside but I haven't compared the internals yet. I seem to remember reading somewhere that they were different but can't recall where. I know that there is a completely different pump for the fresh water side of a fresh water cooled motor, but that's not the pump I'm talking about. Thanks.

kloudie1

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Oct 31, 2011

Ted, the parts book says they are different pumps.. The GM pump is smaller.. impeller specified is 40mm diameter and 19mm wide and the GMF impeller is specified as 50.8mm diameter and 22.1mm wide.. So it seems like you could use the GMF pump on a GM but not vice-versa.. part numbers in my old book are for the GM pump assembly, 128270-4200 and for the GMF pump assembly, 121575-4200.. Check with a Yanmar guy because the numbers may have beeen superceeded and they may have started using the GMF pump for both..

Ted

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Oct 31, 2011

Kloudie1, Thanks for your response. You were absolutely right. I pulled the pumps apart today and confirmed that the fresh water pump impeller is indeed slightly larger than the raw water pump impeller. I didn't realize that they were two entirely different pumps until comparing them side by side. Thanks for the heads up.