Impeller for 4 cyl Yanmar on my Kohler genset

[RickyD]

So I'm about to service my 1990 Yanmar diesel driven Kohler 16kw genset. So I have two used servicable impellers in a kit left by the old owner each with 9 fins. Then I have a new in the box impeller with 10 fins. So my buddy has the same unit and he brought over a spare he had on his boat and it has 12 fins. Which one will pump the most water? Diameter and height and splines are all the same. So I wasn't sure what to do, so I called a Yanmar dealer and asked him to look at the one specified for my engine. He did and it had 9 fins. So then I pull out my impeller which was 6 years old (I know, deferred maintenance) and it had 12 fins. Yes it was a B!tch to take out. What the heck? The 12 fin was working fine. So, I'm going to put the 10 fin unit in and see what the output looks like. My question is a brain teaser. Does pumping a smaller amout of water more often work better than a larger amount less often? I think the 12 will pump less but I want to know what some of you think.

 

[Comodave]

How old is the “new” impeller? They do age just sitting in the box.

 

[Bendit]

Probably won't make much difference. I just changed out a 10 fin impeller on my Kubota genset engine for a 5 fin - all I could get at the time - and the water volume appears to be pretty much the same. Unscientific I know!

 

[RickyD]

Probably won't make much difference. I just changed out a 10 fin impeller on my Kubota genset engine for a 5 fin - all I could get at the time - and the water volume appears to be pretty much the same. Unscientific I know!

I ended up putting a ten fin in and it pumps more water. Than the 12