Micron size

Sep 7, 2011
279
Hunter 1980 37c Illinois
On a diesel Racor filter for our Yanmar engines... what micron size do you run?
Anyone run 30 microns?
3qm30h

Thanks
 
Mar 5, 2012
152
Hunter 37-cutter Saint Augustine
I run a 10 micron racor filter and there is a small filter on the eng, that I think it,s a 2 micron. but not sure.
 
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KD3PC

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Sep 25, 2008
1,069
boatless rainbow Callao, VA
I am in the 10 micron filters camp with Frankies, prior to the engine mounted one at 2 or 3 microns - can't recall. I also use the vacuum gauge on the filter housing as it gives a pretty good indication of things moving and being clear.
 
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Oct 6, 2007
1,023
Hunter H30 1982 Chicago IL
Primary filter is a Racor 30 micron, secondary engine mounted filter is the Yanmar 10 micron.
 
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Jun 8, 2004
994
C&C Frigate 36 St. Margarets Bay, Nova Scotia
Yanmar designs it engines with the filter size of 2 microns to protect the fuel system high pressure pump and injectors - this is why the small filter mounted on the engine is fitted with the 2 micron element. The Racor or other brand filters are usually added at the the time of engine installation and can be whatever you want. If you put a 2 micron element in the Racor, you will never have to change the filter on the engine, but you will change the Racor more often. 30 micron is a 'coarse' pre-filter and you will have to change both the Racor and the on-engine elements at regular intervals. Because the Racor is way over-capacity for my 30 HP at 500 GPM, I compromise and use a 10 micron filter element. I generally change the Racor element every two years and the Yanmar one at twice that interval. YMMV.
 
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Feb 6, 1998
11,665
Canadian Sailcraft 36T Casco Bay, ME
Yanmar designs it engines with the filter size of 2 microns to protect the fuel system high pressure pump and injectors - this is why the small filter mounted on the engine is fitted with the 2 micron element.
On older non common-rail Yanmar engines the on-engine Yanmar filter is not 2 micron. It is rated as a 10-15 micron element.



If one were to purchase a Yanmar branded primary fuel/water separator filter, from Yanmar, it is 30 Micron and nothing more than a re-branded Racor. The Yanmar Part number for the whole kit is 4230B and the filter cartridge only is 4230-0100.
 
Jun 8, 2004
994
C&C Frigate 36 St. Margarets Bay, Nova Scotia
I stand corrected! What is the point of diminishing return for filtering the diesel for an older Yanmar? Maybe I should go back to 2 micron in my primary Racor...
 
Jan 30, 2012
1,123
Nor'Sea 27 "Kiwanda" Portland/ Anacortes
Last edited:
Jun 8, 2004
994
C&C Frigate 36 St. Margarets Bay, Nova Scotia
Good thread Charles - thanks a lot for the link. I currently have a 10 micron Racor primary element and whatever spec the secondary, or 'guard' filter from Yanmar is, so according to the resident experts, I am good to go.