Which Micron filter to use in Racor?

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jefndeb

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Indigo Star
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2006 Mainship 400
Hello,

Its time for me to replace both the primary and secondary fuel filters on our Maniship 400 Yanmar 6LY2AN-STP diesel. I have never replaced them so far but I need to soon.

The issue I have is I am not sure what "Micron level" the element is that is currently in the Racor 900MA Filter assembly and I am not sure what the basic standard is used for a primary and secondary filters, as far as Microns go...

The Parker/Racor spec shows 2, 10 & 30 Micron as my options for the primary.

Which one should I use? Wouldn't you want a really good filter in the first filter?

The second filter, being on the engine itself is a Yanmar Fuel Filter (41650-502330-12). I cant seem to find its micron spec either.

I have a spare Racor 2040N-10 (10 Micron) and 1 of the Yanmar filters as well.

Are those ok to use?

Thanks for your comments.
 

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Your secondary filter on the Yanmar is almost assuredly a 2 micron. Recommendation for the Racor is most likely 10 micron. Many DIY owners will strongly recommend running 2 micron on the racor to avoid changing the secondary. I personally defer to the experts who recommend staged filtration and therefore recommend 10 micron in the racor.

Good luck

Peter
 
I run 10 microns in my Racors but I don’t have a high pressure injection system either. To me it would depend on how difficult it is to change the secondaries. If they are easy to change then go with the 10s. If the secondaries are hard to change then maybe go with 2s. And you will change the 2s more often and the secondaries less often. Some will say that you need a 30 as the first, then 10 and then 2. I only have 2 filters, primary and secondary on the engine. Most will say I need to use 30s in the primaries since the secondaries are about 7 micron. I use 10s and they stay clean and the secondaries never need changing. Each to their own.
 
All filters create resistance to flow. If you have too many fine filters in series the total resistance to flow may make your pumps work harder and/or less flow and/or lower pressure. As the filters filter each ones resistance to flow increases with a resultant decrease in circulation of whatever fluid is being filtered. So resistance varies with use. I change my racors depending on how they look, pressure reading and fixed intervals. Engines are expensive. Filters are cheap.
The manufacturer has figured out at which micron of filtering used for how long in which place in the series is appropriate. So for any fluid (oil, water, fuel) it’s wise to just follow their instructions in their manual if the note it. Believe Peter is correct a 10u then a 2u but would check your manual or ask a yanmar wrench to confirm.
 
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10 mic, except a lot of guys use 30's with Detroits because they pump and return a lot of fuel.
 
10 micron in my 900 tacit and 2 micron on the engine. Cummins 6.7 L common rail.
 
I don't think it matters much. Most of the stuff we want to filter out of the tank fuel is much larger than 2, 10 and 30 mic. And it is mostly gooey and soft, not likely to damage injection equipment. On my personal boat, I generally use a Racor 10mic, and I am pretty sure the secondary is 20mic. Seems backwards, but no harm comes from it. If I have a 30mic on hand, I will use that without a second thought.

If you have a common rail engine, most spec a 10mic primary and use a 2mic secondary. CR engines very sensitive to clean fuel, so if that is the rec, follow it.

Detroits flow a LOT, and 30mic is recommended. Other old skool mechanical injected diesels use what you want. Does not really matter.

I have heard the Racor 2mic reported to clog faster, but that was via anecdotes. I tend not to use those unless customer requests.
 
I can't speak to your specific engine, but on my Yanmar 4JH4-HTE I spoke to Mack Boring (the east coast distributer for my engine) and they said the on-engine filter is measured differently than Racor, but if using the same measurement standard, the on-engine filter would be about 3 to 5 microns. He indicated it wasn't advised to use a 2 micron as the primary Racor. He recommended 30 micron but said he understands people who want to use a 10 micron as primary and he didn't have any real issue with that. He said it would need to be replace more frequently - but if you don't care about the inconsequential cost of that then go for 10 micron as a primary Racor.

So that's what I ran.
 
My old F.L. which will eat about anything and has almost 0 return. The fuel in my tanks is pristine. (the tanks have been renewed)

30's in the Raycors, 10's in the secondaries.

pete
 
I would go with whatever Yanmar recommends for that specific engine. Might be timely to get a manual for it while you are at it. Mack Boring is an excellent source of info for all things Yanmar, and they also give training classes aimed at the recreational boater. They list a variety of service and dealer companies in the general Savannah area.

https://mackboring.com/
 
Just go up in size until they plug up too fast.

I use 30m
 
I have the manual thank you but it does not specify any type of micron filter
 
I use a 2 micron, but my max fuel flow is only 1 gph so it's hard to plug it. Last year I had a wot issue that reducing my throttle to half cleared up so I knew my filter was clogging. I had 700 hours on that filter, the first one I have ever had slow the fuel flow since I have owned the boat. Recommended to change at 500 hours, I will just start every season with a new filter. The secondary is a 1 micron Yanmar filter, and I believe fuel flow has as much to do with the filtration as anything. More fuel flowing, the larger filter you should probably be using.
 
The lower the micron number, the longer fuel system components last. I run 2's in the Racors, buy clean fuel and use a diesel treatment that includes a biocide. When I rebuilt my Detroit mains, I had the injectors rebuilt. Not changed since then, about 10 years.
 
Well I changed both primary and secondary fuel filters today, and actually also used the Parker/Racor 900MA rebuild kit to replace gaskets O-rings etc. Its super clean now..

Is it normal for the bowl have this much trash in it?20210312_122726.jpeg20210312_122736.jpeg20210227_103238.jpeg
 
I use 2's in the Racors and the same on the JD 4024 engine. But then, fuel rate is usually 1.5 gallons per hour, occasionally over 2, and never more than 4.
 
Well, I have owned this boat or a little over a year and this is the first time I have replaced the fuel filters. I knew based on the bowl it was time. I am glad I did too.
 
I don't believe you are correct.

AKDoug said:
I use a 2 micron, but my max fuel flow is only 1 gph so it's hard to plug it. Last year I had a wot issue that reducing my throttle to half cleared up so I knew my filter was clogging. I had 700 hours on that filter, the first one I have ever had slow the fuel flow since I have owned the boat. Recommended to change at 500 hours, I will just start every season with a new filter. The secondary is a 1 micron Yanmar filter, and I believe fuel flow has as much to do with the filtration as anything. More fuel flowing, the larger filter you should probably be using.
Click to expand...

I think you might be confusing fuel consumption with fuel flow. There is considerably more fuel sent to high pressure pump than what the engine consumes, and all this fuel passes through both filters, before returning to fuel tank.
Yanmar recommends a 30 micron first stage filter, with the on-engine filter in the range of 6-10 microns. Note that common rail engines are more stringent in their requirements.
 
Like others here, primary Racor 900MA was found with a 10 micron filter, and the CAT filter on the engine is 2 micron. Both changed out a few months after I purchased the boat last July due to engine being starved on the occasional WOT test. I have no records of when these were last changed by the previous owner. So, I will be watching this closely to see when the primary needs to be done again, and I installed a new vacuum gauge on the top of the Racor (with recording needle!) so I can monitor (these replace the "T" handle). Currently shows 4psi. I was on the boat yesterday, but forgot to inspect the glass bowl.

IF that primary Racor clogs up sooner than I think it should I will have two choices: 1. Install a second new Racor filter upstream and put a 30 micron in it. OR 2. get both fuel tanks polished. OR both. (So far, my attempts to find someone with a portable fuel polishing system near me have failed.) May have to make my own or buy one.

Interestingly, when changing the fuel filters mechanic #1 simply filled the filter elements with fuel so he would not have to bleed the air out of the fuel lines. Talking with a mechanic #2, he said CAT recommends NOT doing that because the fuel he pours into the elements will not be filtered. So it risks a clogged injector. Mechanic #2 wins the work moving forward... and will have to teach me how to bleed my lines! LOL
 
Redsky49 said:
I think you might be confusing fuel consumption with fuel flow. There is considerably more fuel sent to high pressure pump than what the engine consumes, and all this fuel passes through both filters, before returning to fuel tank.
Yanmar recommends a 30 micron first stage filter, with the on-engine filter in the range of 6-10 microns. Note that common rail engines are more stringent in their requirements.
Click to expand...

My 4JH doesn't have a return line to the fuel tank, so it probably only filters what the engine is consuming.

Also not a common rail engine.
 
Twin 4LHA-STP

We use 30 micron Racors in our MS Pilot 34 per Mack Boring and our local Yanmar dealer. We change them every year, no issues.
 
Capt Ray said:
Interestingly, when changing the fuel filters mechanic #1 simply filled the filter elements with fuel so he would not have to bleed the air out of the fuel lines. Talking with a mechanic #2, he said CAT recommends NOT doing that because the fuel he pours into the elements will not be filtered. So it risks a clogged injector. Mechanic #2 wins the work moving forward... and will have to teach me how to bleed my lines! LOL
Click to expand...

If you have Racor 500 filter bodies, when you change your filters all you need to do is open the valve to the fuel supply before you put the lid on, wait till the fuel level rises to the top, put the lid on before overflow, tighten, start your engine. The incoming fuel is unfiltered, but is entering the housing as always, goes through the new filter element before going out to the engine. If you have the engine running, sucking fuel through the new element, no unfiltered fuel will ever go to the engine. Once running, if there is any air in the housing it will quickly be replaced by airless fuel and the engine won't even notice it.

You only need gravity fuel pressure in the feed line, so the filters should be mounted below the fuel level in your tanks. If you don't have any gravity flow, back to using the thumb lever priming pump on the engine, maybe a few hundred strokes, to pull fuel in from the tank.
 
Our Fleming 55 uses 10 micron but I'm dropping to 2 micron. Why? Two reasons. Parker Hannifin has assured me the max flow rate would not be affected (Cummins 6CTA 8.3) and I'd far prefer to change a Racor fuel filter when caught in a nasty sea rather than a hot engine filter.
 
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