Diesel In-Line Fuel Filter

[Homer Shannon]

Nearly every year I have had at least one incident where my Yanmar SB12 diesel motor gets air in the line and the engine comes to a stop – usually at a very inconvenient time. The source of my problems is always the Yanmar fuel bowl, which is made of soft material and there is no way to properly torque the vent screw or the banjo bolts without risk of stripping the threads of the bolt holes. Last fall, while working on the motor, I finally did fully strip the threads of the line to the high pressure pump and I made a decision to change the arrangement.

The change I went with was an in-line fuel filter and a separate fuel return line to the fuel tank that completely eliminates the Yanmar fuel bowl – I have actually removed it from the motor. This change has resulted in zero fuel problems this past season and I’m quite pleased with the solution.

Recently, a friend of mine with a new-to-him boat with a Yanmar 3GN30F motor, ran into issues related to the fuel bowl, which I believe is exactly the same except for the fuel return line. The fuel return line goes to the fuel tank and the banjo bolt hole is blocked with a standard bolt. I advised him of my solution to the problem and he asked me to send along a link for the fuel filter that I am using.

The filter I installed is a WIX 33001. When I went and found a link for the product to send to my friend I noticed in the specifications that WIX states: (for use w/gasoline only – for diesel, use 33971). Whoops – what have I done? Part Details

The stock Yanmar filter is a 2 micron filter but I have read in many places that a 10 micron filter is acceptable. The 33001 is a 12 micron filter - pretty close and as good as I could find in an in-line filter. WIX’ suggested replacement is part 33971, a 140 micron filter – way too coarse. So, I have two questions:

1. What is it about the WIX 33001 filter that makes it unacceptable for use in diesel motors?

2. Is there a know in-line filter that can be used that filters to less than 10 microns?

[David M]

You will need a really large primary filter if you want to start filtering at less than 10 microns because filtering at 2 is going to clog much sooner than filtering at 10. No diesel that I know of needs finer that 10 microns. Yes, for a Diesel, 140 microns is not fine enough. I would stick with filters made for Diesel engines only for your and your friends Diesel.

[Homer Shannon]

My primary filter is a WIX 33110, which is rated at 10 microns. From what I've read, there isn't much difference between a gas and diesel fuel filter - mostly shape for water collection. The WIX inline filter does not need to do water collection as the primary filter does that. All of the inline filters that I've found for diesel are rated in the 100 to 150 micron range. It seems they are more concerned with flow than with filtering.

I'm thinking that my use of the WIX 33001 is OK.

[a64pilot]

I’m not saying your wrong, but I’ve not been able to find a micron rating for my Yanmar final filter. I doubt it’s a 2 micron though, I’ve seen 6 written, but not officially.
Yanmar recommends a 30 micron initial filter, and of course their final filter. I’ve seen where the reason to not run a very fine initial filter is restriction of fuel flow.
Many people run a 2 micron primary filter, and no harm has come of it to my knowledge.
Fuel can’t be too clean, only too dirty. Personally I run the recommended 30 micron primary filter and usually change filters every year or so. I change them mostly just to start the season with new filters, not because they clog.

Diesel fuel has different solvent qualities than gasoline, for instance an outboard primer bulb will last for years in gasoline and never fail, but eventually if used for Diesel it will split. It may take a long time, but it will eventually fail.
Presumably different materials, maybe the glue in a filter or maybe the media itself is different for Diesel and Gasoline. They would make more money having one filter used for both, so I doubt it’s some kind of marketing ploy, I believe there is a difference, just can’t speak as to what it is.

[Lepke]

If your fuel is clean, a 2 micron filter can last a long time. I use Racor 900 primaries and have 2 micron elements. I change the element at 500 hours. Besides generators, my twin Detroits draw 70 gallons/hour and return 60+ gallons/hour. So at the filter change the element has filtered or refiltered more than 35,000 gallons.

[Nicholson58]

I lost the first stage 1500 psi boost pump on my Westerbeke due to silting in of the vanes. While it was getting repaired I researched and installed a polishing filter, 1 micron. The loop circulates fuel at 45 gph from the day tank. The clean diesel return line to the tank is the supply to the usual Racor and other filters for the main engine and generator. I change the large polisher element annually and have not changed any other filter for four years. The Racor bowls are spotless.

[Homer Shannon]

I did some more searching on this topic and found that the Yanmar 104500-55710 fuel bowl filter is sold by a bunch of other manufactures, some of which list the filtering capability. None of them are 2 micron filters and even the Yanmar part is not listed at 2 microns. I'm not sure where the 2 micron specification originated, but I know I didn't make it up. Here's what I found:

Yanmar - Hamilton Marine, 19 micron
Yanmar - TOAD, 10-15 micron
AC Delco C7516 26 micron
WIX 33262 19 micron
Donaldson P502134 16 micron

So, what I am looking for is a 5/16" inlet/outlet, diesel approved, in-line filter with around 10 micron filtering. I've looked at dozens of in-line filters and none of them meet this specification; most of the 5/16" diesel approved filters do not have a micron rating at all.

If anyone knows a solid candidate, please pass the part number along.

[a64pilot]

Why do you want an in-line filter?
They are usually pretty much just rock catchers, as due to their small size they can’t filter down to a fine level and still flow much fuel.
If price is the reason, get one of the knock off Racor 500’s, the reason to get a 500 is it’s so common filter cartridges are available just about everywhere, and they are very often less expensive than the smaller less expensive Racor filters.
So not only will the 500 hold a lot more dirt before it needs changing, it’s often much less expensive.

Look at the prices of the cartridges to see what I mean.
Save the inline for your outboard
https://search.defender.com/?express...20elements&s=1

[a64pilot]

2 micron is the finest commonly available fuel filter, people who desire to filter to the finest level will chose a 2 micron.
So many believe a 2 micron is what is called for. So long as your filter is large enough that a 2 micron element doesn’t cause undue restriction there is no harm in filtering to 2 micron, fuel can’t be too clean.

[Cheechako]

I avoided gas filters as I was worried that whatever they are glued, or saturated with, was susceptible to deterioration in diesel. I couldn't think of any other reason they would not rate them for diesel, but... who knows...?
I also found using squeeze bulbs in line for priming the diesel on a couple different boats that one brand got mushy and swelled up, while others didn't. Obviously effected by diesel when meant for gas.

IIRC my 3GM30's Yanmar primary came as 2 micron, but can't remember any details. 5 micron is fine for me. But if you have a nice clean system 2 micron is fine too.

[Homer Shannon]

It would be nice if manufactures would state these reason so we could be a bit more educated about our choices. I've had a squeeze bulb in the fuel line for at least 15 years and it seems fine - though I think I'm going to give it a good check up! The fuel filter has been installed since June and everything has worked perfectly this year. It's hard to argue with long term success, but knowing is better.

[Midnight Son]

After conversations with diesel engineers (automotive) about final fuel filtration. If you have a type of common rail system, filter to less than 8 microns (4 microns is preferable). Old school injection, 10 micron is sufficient.
Cheers all

[Nicholson58]

We have Franz. I have one each bypass type on each engine crankcase. These are 1 micron absolute. They are changed every 4-6 months. I do not change the oil unless I see a viscosity drop as evidenced by oil pressure. This saves 3.5 gallons per change, disposal and very expensive Caribbean purchase. Over the road truckers have been using these on crankcase oil or centrifugal cleaners and regularly go over 100,000 miles without oil change. Measured wear at rebuild is negligible. The Franz bypass filter has an orifice that can be removed for in line operation. They will easily pass enough diesel to run our typical small marine engine. If you don’t have a primer pump it may be necessary to add one.

I have a 6” dia X 12” long in line Franz 1 micron on my fuel polisher. Read my post above somewhere. This element is a seasonal change. I haven’t changed the regular, now backup, filters in three years. See photo. Cardboard tube is a new element.

Here are two makers of similar filters. They also sell assembled systems. These are what is referred to as a ‘toilet paper filter’. The element is a tight roll of paper. Oil enters one end and travels along the roll lengthwise.




Gulf Coast Filters, Inc. Specializing in Bypass Oil filters, Fuel filters, Hydraulic filters and Custom filtering

https://www.frantzfilters.com/?gclid...RoCUZwQAvD_BwE

[Compass790]

Originally Posted by Homer Shannon

I did some more searching on this topic and found that the Yanmar 104500-55710 fuel bowl filter is sold by a bunch of other manufactures, some of which list the filtering capability. None of them are 2 micron filters and even the Yanmar part is not listed at 2 microns. I'm not sure where the 2 micron specification originated, but I know I didn't make it up. Here's what I found:

Yanmar - Hamilton Marine, 19 micron
Yanmar - TOAD, 10-15 micron
AC Delco C7516 26 micron
WIX 33262 19 micron
Donaldson P502134 16 micron

So, what I am looking for is a 5/16" inlet/outlet, diesel approved, in-line filter with around 10 micron filtering. I've looked at dozens of in-line filters and none of them meet this specification; most of the 5/16" diesel approved filters do not have a micron rating at all.

If anyone knows a solid candidate, please pass the part number along.

that's interesting Homer, Yanmar part salesman told me they were 10micron but wether he made it up i don't know.
I have a Napa gold 3166 fuel filter that is 10 micron to fit CAV type filter mount. You can get 8mm or 5/16" hosetail fittings for the filter mount easy
Here is an example of what I'm talking about.
https://www.ebay.com/itm/C5NE9165C-D.../123286299633?
Some people don't like CAV type filter mounts but if you don't over tighten the wrong bolt & break the glass bowl
they are ok. You'll only do it once.
What A64 pilot said re those little inline things.

[oleman]

Throw the cheap filter set away and go to the WIX catalog and chose a commercial spin-on filter and base and never look back! We use one that is used on a Cummings engine so filter canister is available world wide. One issue is the filters are mostly large so space must be available.