Diesel Filters

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Aug 16, 2009
1,000
Hunter 1986 H31 California Yacht Marina, Chula Vista, CA
Was thinking of adding a second stage or possibly an alternate diesel fuel filter. Then I began to wonder what the difference between a marine filter/separator such as racor, and something from a land based engine. Besides the price differential, that is.
 

capta

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Jun 4, 2009
5,074
Pearson 530 Admiralty Bay, Bequia SVG
Racor filters (500 & up) are accessible from the top, lessening any chance for spilling fuel. The clear bowl below the element is nice to see what's in there (water or sediment). Best of all there are three filter elements available; 5, 10 or 20 microns.
I wouldn't use any other filter for a primary.
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
Not much difference between land based and marine based for Racors, etc.

Let me offer these thoughts:

A second pre-filter should be to prolong the service life of the immediate downstream final filter and should be approx. 5 times larger in retention µM size than the one that its 'protecting'. .... and this discussion does not include the engine mounted 'guard filter' which should be ignored when it come to filtration selection.

Typically when a filter is prematurely plugging, the best 'bang for the buck' .... is to double the surface area of that filter which in turn usually nearly always triples the on-stream service life of the all important final filter. You can do this by using 'double length' spin on cartridges or using two filters + housings in parallel with both filters always 'on-line'; if youre using a canister type you can simple buy a longer 'bowl'.
However when looking at a plugged filter element, if one SEES a lot of loose crud on the surface of the pleats, then adding a prefilter is usually then the first choice before 'doubling up' on the SURFACE AREA of the final filter (that engine mounted 'guard' or 'last chance' filter still being ignored).

Ultimately, the best course of action in any premature filter plugging on a boat is: get inside and CLEAN OUT THE TANK.

;-)
 
Last edited:
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
Our H'31 came with a Fram primary filter. Are you considering adding additional filters or replacing it?
 

trasel

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Dec 26, 2011
56
Endeavour 32 Middle River, Md.
cleaning out the tank

Not much difference between land based and marine based for Racors, etc.

Let me offer these thoughts:

A second pre-filter should be to prolong the service life of the immediate downstream final filter and should be approx. 5 times larger in retention µM size than the one that its 'protecting'. .... and this discussion does not include the engine mounted 'guard filter' which should be ignored when it come to filtration selection.

Typically when a filter is prematurely plugging, the best 'bang for the buck' .... is to double the surface area of that filter which in turn usually nearly always triples the on-stream service life of the all important final filter. You can do this by using 'double length' spin on cartridges or using two filters + housings in parallel with both filters always 'on-line'; if youre using a canister type you can simple buy a longer 'bowl'.
However when looking at a plugged filter element, if one SEES a lot of loose crud on the surface of the pleats, then adding a prefilter is usually then the first choice before 'doubling up' on the SURFACE AREA of the final filter (that engine mounted 'guard' or 'last chance' filter still being ignored).

Ultimately, the best course of action in any premature filter plugging on a boat is: get inside and CLEAN OUT THE TANK.

;-)
How does one "clean out the tank"?
 
Jan 22, 2008
551
NorSea 27 Az., Doing the To-Do list
If your tank does not have one, they make clean-out plates that you can retrofit into your tank. Not a lot of cost, but it does take cutting the tank.

One tank I did, I dropped a chunk of dry ice in it to remove all the O2 before cutting. Worked very well for me.

Greg
 
Oct 17, 2011
2,809
Ericson 29 Southport..
Clean tanks..

If you elect to pull the tank out and clean it, I can save you some time and bucks. Being the diesel fanatic that I am, and knowing clean fuel is of the Lord, out came the tank on this boat IMMEDIATELY! And as usual, bought a couple of absolutely USELESS products on the shelf that "cleans fuel", better milage, regrows hair, and ends world hunger. Junk. I would have had better results peeing on the gelcoat to shine it. Carburetor dip cleaner in a gallon can, baby. It was less than 20 bucks, and I poured about half of it in a 20 gallon tank. (I saved the other half for a "final" rinse that proved to be entirely unnecessary). The inside of the tank the next morning was immaculate. Truly looked as clean as the day it was made. Never once reached inside to wipe anything, just sloshed it around a couple of times. In retrospect I could have just as easily done this inframe, sucking out the residue, but I was truly amazed. Highly recommend it.
And I tote my own fuel from from busy truckstops. I realize the only difference is red dye and cost, but I don't want that nasty looking red stuff on my boat. And my filters and fuel stay looking pristine. This road fuel is more than likely overkill, and just a stupid obsession, but I like paying taxes to a poor government. God bless them, they need it.
And I hate red fuel.
But surprisingly, I've never had a fuel issue. Don't anticipate it. The fuel is the lifesblood of the diesel, and the money I spend on this sailing madness, I'm gonna get cheap here?
Riiiiiiight..
 
Jan 27, 2008
3,092
ODay 35 Beaufort, NC
I didn't try this myself, I installed a Racor, but you can also get diesel filters at Tractor Supply stores that are a heck of a lot less costly. They sell them to farmers for their various diesel motors out on the farms. What I saw were cartridge type spin on filters but would likely work just fine.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
The Racor 120 is about $70-80. I mounted two of the in a bypass setup so I can swithch from one to the other within a minute.
 
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