Recommended microns for fuel filters?

[Tashahacker]

Hi again! Sorry to bombard with questions but I'm doing a major supply shop in Fort Lauderdale and need help...getting conflicting advice!

On our fuel system, we currently have a 10 micron primary filter on our Racor. And we have a 2 micron filter on our actual engine (secondary).

Someone recommended we use a 30 micron primary and 10 micron secondary because of frequent clogging...

Can anyone comment on that or offer a recommendation?

Thanks,

Tasha
s/v Hideaway

[Stu Jackson]

Fuel Filtration 101 (with both primary Racor and secondary engine filter identification) 
http://c34.org/bbs/index.php/topic,1124.0.html

and

http://c34.org/bbs/index.php/topic,6475.0.html

The "101 Topics" (http://c34.org/bbs/index.php/topic,6437.0.html) have a lot of the kinds of information that you're asking about, and may ask in your next question(s)! 

[Ron Hill]

Tasha : I think that you have it backwards, I know of no screw-on 2 micron canaster filters that will fit on the engine.  On the Racor YES, on the engine NO.

Most engine screw on-filters are 10 and some 15 micron in filteration size. Racor has two sizes - 2 and 10 micron.  {Note (Stu)  30 micron filters are available, too.}  The size is so noted in the part number.

I use 2 micron size on the Racor and 10 micron on the engine.

There are numerious discussions on this topic in WiKi and discussion topics on this message board.

[Stewartn]

I believe the manual for the M35 B has OEM parts that are 30 Micron on the Racor and 10 Micron on the engine. I have used this for five years and been happy. No matter what, the larger micron is the first filter from the tank (Racor) . Then the smaller . 1st catch the bigger stuff and then the smaller. Rgds.

[Ron Hill]

Guys : I know of nowhere in any of the M25, M25XP, M35 and M35BC manuals (Operators pg 19,20 & Parts pg 29) that state the filtering size(in microns) of the spin on engine fuel filter.  You have to go to the filter manufacturer to find out the degree of filtration. Usually between 10m and 15m

On the Racor filter the manufacturer has stamped the micron size filteration on each cartrage (usually 2m or 10m).

A thought

[BillG]

if you are having frequent cloggings with a 10 micron filter, you may want to look at some of the past
articles on cleaning the fuel tank, rough waters can stir up that junk in the bottom of the tank at the most
inopportune times

[Ron Hill]

Guys : Bill make a good point.

Starbrite (starbright?) makes a fuel tank enzyme cleaner.  I've used it for the past couple of years and believe that it is working.  Haven't pulled the tank of late to see if it really is.
At least you can't "overdose" and eat up your injection pump the way I suspect that Biobor Jr did!?!

[mainesail]

This was over 15 years use of Soltron / Startron treatments, including at least two "shock" doses........ Startron was Soltron before Starbrite re-labeled/licensed it for US distribution.



The only things I've found that can help keep a tank clean are an on-board dedicated polishing system and manual cleanings.

[Indian Falls]

Keep in mind that a micron is 1 millionth of a meter...   1/10,000th of a meter is about the diameter of a hair...so the difference on a "dirt scale" between 5 micron and 10 micron is really nothing.  Our systems tend to be filtering bio-mass rather than sand and dirt.  In my mind, if stuff does get past the filter it ought not be too harmful to the moving parts.  The real concern is premature clogging of filters when you're trying to get somewhere. 
IF there is a 15 micron filter on the engine, then a 25 micron filter in the racor, and you have clogging issues I'd put a 50 micron pre-filter on the input to the Racor.  I think 50 millionths is still only 20% of the size of a hair...

Or you can pull your tank and wash it out.  I was amazed at how clean my tank actually was.  I also had the "original" filter on the engine 20 years 1400 plus hours.  Yes I did change that filter.
My cleaning method was to put two gals of simple green and 2 gals of water in the tank, put it in the back of my truck and drive everywhere with it until the temps got down so low the stuff might freeze.  A rinse with boiling water three times and..... clean enough.

[Ralph Masters]

Great cleaning method.