Fuel Filtration 101 & Racor fuel filter numbers

Stu Jackson · December 08, 2009, 10:51:17 AM

For the same reason Maine Sail and others have warned against putting a 2 micron on the Racor primary, I would caution against even considering doing so on the secondary. Didn't someone (like, everybody!) say the secondary filter is 10 micron?

Mike and Joanne Stimmler · December 08, 2009, 11:42:45 AM

Stu, you're right about Mainsail warning about putting on a 2 micron filter, but he was talking about a delivery he was doing on a unfamiliar boat.

My point is that if you've been using a 2 micron filter for years with no problems, you can feel all warm and fuzzy inside knowing that your fuel system and tank is in good shape.

THEN, if you start having problems with clogged filters, you know something is wrong and should be checked.

I'm pretty sure that the spin on filter that I'm using is 30 micron but I thought that was all that's available in the spin on type.

Stu Jackson · December 08, 2009, 12:48:45 PM

I hear ya, Mike, but I think the issue is not clogged filterS, it's which filter gets clogged and is easy to get to, plus what's available on the market. If all they make are 30 micron filters for the spin on secondary filters, issue is over. But I'd never put a smaller micron filter on the engine anyway.

I understand Maine Sail's story, but if you've ever traveled with your boat, you have NO CLUE of the condition of the fuel in a new-to-you harbor. I know "MY" fuel guy is cool and has fine fuel, but I do not know what Bodega Bay or Monterey may be like when I visit there.

So, as you say, the choices are pretty easy:

--- Keep the 10 on the secondary

--- Decide what you want to do with the primary

2 micron catches everything, been working for us for years
keeps the secondary cleaner
downside: may plug up quicker on poor dirty fuel

10 micron primary matches the secondary, why bother?

Your boat, your choice.

Mike and Joanne Stimmler · December 08, 2009, 01:46:56 PM

Very good points,Stu.
Bottom line I guess is, know what's available and use what works for you and what you feel comfortable with.

DaveM · December 08, 2009, 03:19:07 PM

Well Mike good question on finding a 2 micron for an M25-xp. I got a Wix 33390 spin on two years ago from an auto parts store being told that it matched another brand I had that was supposed to be a 2 micron. Well when I looked it up on Wix site a 33390 is a 10 micron. Oh well. While on Wix site I looked for the recommended fuel filter for a Kubota D950 (the base of the M25-xp) and low and behold the recommendation was a Wix 33390. There you go.

Goodwinds
DaveM

Juan · December 08, 2009, 03:42:35 PM

Just, a more general question about fuel filters: has anybody written detailed instructions on how to change both (primary and secondary) fuel filters?

Thanks a lot!

Juan

Ron Hill · December 08, 2009, 05:34:39 PM

Guys, Susan and D.Gill : On this topic - WOW! Here are some of the facts of life:

1. The engine filter is about 10 to 15 micron filtration - you can't change that (that I know of) !

2. The Racor filter which is the first filter that the fuel reaches from the tank, can be change to either
a 2 or 10 or 30 micron size! All of the Racor "spin-on" filters have a water seperator bowl on the bottom.

3. The ideal system would have the courser filter first and you can do that. I placed an inline 10 to 15 micron filter between the fuel tank and the Racor. Wrote an article on how to do it. The problem is that it got TOOO messy trying to change the inline filter in the space that I had under the C34 sink!! & gave up

4. If you have a separate fuel polishing system with a 10 micron Racor, the 2 micron Racor before the engine fuel filter works just fine.

5. If you use the 2 micron Racor then you seldom have to change the 10/15 micron engine filter (maybe every 3/5 years). For those of you that have not changed the engine filter - you're in for a treat!!

6. I use the 2 micron Racor, but use the Starbrite enzyme additive, and now do not have a problem

A few thoughts

DaveM · December 08, 2009, 06:25:48 PM

I wanted to answer a question on the engine filter that has been bugging me for a while and that is what does the engine OEM call for. This tread prompted me to search for the the M-25xp Kubota engine fuel filter which I understand from this site is a B7200 tractor. I found the Kubota filter which is a Wiz 33389, 10 micron. The spin on equivalent is of course the Wix 33390, 10 micron. That answers that question for me.

Good Winds
DaveM

Stu Jackson · December 08, 2009, 10:22:40 PM

Quote from: Juan on December 08, 2009, 03:42:35 PM
Just, a more general question about fuel filters: has anybody written detailed instructions on how to change both (primary and secondary) fuel filters?

Sure. When having questions about a specific subject, go to the WIKI.

http://www.c34.org/wiki/index.php?title=How_to_Change_Your_Racor_Filter

The secondary engine filter is much the same, the access is different and harder.

From an edited earlier post on fuel bleeding:

I do not fill the secondary (engine mounted) filter with fuel, since it is a bear to get back there and put a strap wrench on it, no less getting my hand in to get the threads started. If it is empty, I can't spill any fuel. It is difficult to avoid spilling fuel when I remove the old one. I bought a smaller strap wrench for that filter.

Once the new clean secondary filter is on, I just open that bolt, run the electric fuel pump by turning on the key switch at the panel, wait till the air is gone, close the bolt, and I'm done. I installed a fuel pump shutoff toggle switch in the engine compartment so that I can control the pump without having to jump up into the cockpit.

Once the filters are changed, bleeding is next, so, a very good discussion of fuel bleeding is here: Theoretical Fuel Bleeding: http://c34.org/bbs/index.php/topic,2884.0.html

Stu Jackson · December 09, 2009, 09:50:56 AM

If the secondary is a 10 micron filter, then things change in my Reply #32 above, rather than the 30 micron I used. I shoulda known better because an earlier post said it was 10 micron. My bad. [Corrected]

Following that logic, though, I'm staying with the 2 micron primary Racor, because I do NOT want that secondary clogging on me first (if I switched to an equal 10 or larger 30 micron primary). I'm willing to put up with a rough water or bad fuel primary change, a la Mike's point. I do NOT want the secondary clogging first: then the scenario would be to change the larger micron primary, but still have a mess with no fuel flow, and then have to change the secondary anyway. That's plain Nuts.

If one of the filters plugs, I want it to be the Racor not the secondary.

Here's an earlier discussion of this issue: http://c34.org/bbs/index.php/topic,4462.0.html

You can read much more if you search "secondary filter" with the quotation marks. Some fun stuff back there!

Ron Hill · December 10, 2009, 03:06:01 PM

Guys : We've about beat this topic to death and as I mentioned "if you haven't changed the fuel filter(on the engine) you're in for a real treat"
In my limited experience of 21 years here's what I've found changing the engine fuel filter :
1. You are in a cramped space just getting to the starboard side of the engine.
2. I've always changed that filter with the engine cold. I couldn't imagine what it would be like HOT !!
3. That filter never seems to seal the first time and always need to tightened some more. That makes the filter that much harder to untighten.
4 Even if you fill the filter with fuel you MUST use the bleed nut(on top of the bracket) to get the air out of the filter/line, as the fuel in the line to the injection pump comes out when you remove the old filter.
5. Don't care how careful you are with that filter change, I always still spilled fuel!!

Blows my mind just thinking of doing that job while the engine is hot and in any kind of a pitching sea.
A few thoughts

sail4dale · December 10, 2009, 05:53:46 PM

Gosh .... I guess I didn't really understand the problem. I changed the engine filter and it
was a no brainer Is the MK II different that the MKI?

DaveM · December 10, 2009, 06:04:13 PM

I sure understand the argument about changing the Primary filter is easier than the engine mounted filter especially when everything is hot.

Sail4Dale what got me started on the idea that I had to use a 30 micron to get water separator function I finally found in the page of Racor flyer, portion attached. Note the tying the water separator function with the 30 micron. I am assuming from your comment and experience that you will still get water separator function with a 2 micron filter? Thanks

Goodwinds
Davem

Ken Juul · December 11, 2009, 04:46:36 AM

I think the key to the confusion is "turbine series". From my limited research, turbine series filters rely on high volume/flow to spin the the water out of the fuel. They also have drop in filters rather than spin on. I think the standard spin on routes unfiltered fuel to the bottom and clean fuel comes out the top. Water is supposed to "fall out" of the fuel as it makes the turn to go back up.