Fuel filter questions

[sailingharry]

Originally Posted by capt jgw

If the fuel or tank is dirty a 2m filter will plug up quickly and at the worse possible time, probably in heavy weather. Rough water will stir the tank and raise the crud off the bottom.

This is often stated, and it makes intuitive sense. I'm not 100% convinced.


For this to be true, a 15 micron first filter would presumably let bunches of smaller stuff through, so it won't clog up -- which would overwhelm the second filter (which rarely has a vacuum gauge, so you have no idea what's happening there). A 2 micron first filter would stop all the big stuff, but also the small stuff. So it will clog faster than a free standing 15 micron, but I'm not sure that it will clog significantly faster than the 15 micron followed by a small 2 micron engine mounted filter.



I'm not even convinced that a 15 micron Racor followed by a 2 micron Racor would last longer than two 2 micron Racors in parallel (same number/cost/space as two in series)


Is there any research/test/controlled studies on this?


For sure, if you run two filters, you absolutely ought to have two vacuum gauges so you know what's doing what.

[Bowdrie]

I too use a filtration type funnel to fill the tank with the primary being a 2-micron Racor.
Also got rid of the engine mounted secondary and use a remote secondary.
All has worked well over the years.
A Carter electric pump is between the two filters with an assortment of valves to allow for different pumping scenarios.

[Cheechako]

I think the smallest I ever used was 5 micron. I would worry about 2 mic blocking too fast if fuel is not good. What did the engine maker put on the stock engine mounted filter? I assume they determined that was good enough for the injection pump.
My fuel was kept clean and eventually I used 10 mic in the Racor.

On one boat I had dual filters in parallel with 3 way valves. If one clogs you just turn the valve to a fresh filter. You can then keep running and put a fresh filter in the clogged one.

[Bowdrie]

Originally Posted by Cheechako

What did the engine maker put on the stock engine mounted filter? I assume they determined that was good enough for the injection pump.

It's not a question of "How good or how fine is the filtration on an engine mounted filter".
The primary design criteria of engine mounted filters, (oil or fuel,) invariably seems to be;
"How can we incorporate/mount the filters in such a way as to guarantee difficult access in a cramped engine space as well as spillage when the elements are changed".

[sailingharry]

Originally Posted by Cheechako

What did the engine maker put on the stock engine mounted filter? I assume they determined that was good enough for the injection pump.
one.

That is an exceptionally difficult question to answer, and I'm not been able to find a definitive source. For sure, unlike a Racor filter, the micron rating is not on the box or the filter anywhere.
Toad Marine says that Yanmar states the filter is 10 to 15 micron. Read here:
https://shop.toadmarinesupply.com/sh...u=104500-55710

Over on the trawler forum, a poster with over 5,555 posts states the filter is most assuredly a 2 micron filter.
https://www.trawlerforum.com/forums/...cor-56624.html

Yanmar themselves, without providing it in the form of a specification, states in the description that it will trap particles as small as 1 micron. Frankly, I find that somewhat hard to believe.
https://www.yanmar.com/eu/industrial.../fuel-filters/

[newhaul]

Originally Posted by skipperpete

Recently a friend of mine had a serious diesel injector pump failure (seized hydraulic head on Perkins 4-108 DPA injector pump)and after she’d finished the repair asked if there was any way to stop this happening again and leaving her adrift at sea waiting for a favorable breeze. Now, I know the general opinion on this forum regarding fuel filters is that there should be a 10-15 micron primary and a 2 micron secondary but I unrepentantly told her that the best way was to only use 2 micron for both primary and secondary........ok, put down the pitchforks and hold off for a moment with the google search until I state my case.
1. This boat is in a region not well known for clean fuel availability
2. Usually no reliable dockside refueling
3. Fuel transported to the boat in 20litre jugs.
4. Many folks have very old fuel of dubious quality in their tanks.

I maintain that the ONLY goal is to make sure that fuel cleaned to 2 micron ever reaches the injector pump and I don’t mind changing a lot of primaries to make sure that the secondary remains pristinely clean and not semi blocked by all the all the 14 micron crap that the primary lets pass. I suggest that the primary filter be a big one to avoid high negative pressure in the suction line and that it be an easy filter to replace and bleed. If you have a common rail engine it’s even more imperative that only ultra clean fuel makes it to the HP pump.
Racor and most of the popular filter manufacturers recommend the 15-30 micron primary and 2 micron secondary so I’m swimming against the tide here but I definitely think a big ol Caterpillar 2 micron spin on as a primary beats a little 15-30 micron Racor hands down for both price and efficiency.
Interested to hear the views of cruisers who have actually thought about this and if anyone on the planet agrees with me. [ATTACH].
Here’s what 2 micron looks like.

My 2 cents worth is use a baja filter .

https://harborshoppers.com/baja-dies...diesel-filter/

For the rest a 10 micron racor centrifugal primary is plenty for me but my mitsubishi has a 5 micron onboard combined in the electric pump housing which then goes to a 2 micron that feeds the injection pump.

Main is the Baja stops the dock crud and water from questionable sources .

[skipperpete]

Originally Posted by SY Harmony

Filtration discussions are almost as bad as oil discussions.
It’s all dependent on the fuel system of the engine. As a rule, electronic engines need more than mechanical.

While Yanmar only ships the small engine mounted filter. Their instal manual does recommend additional filtration. Same with all the brands.
As far as equipment, they usually have longer service intervals and multiple filters and/or water separators.

Good point SY Harmony, rotary injector pumps have a very low tolerance for water or dirty fuel and common rail systems have Zero tolerance but the Bosch type (plunger/helix) are very forgiving over the short term and often wear out rather than seize up.

[skipperpete]

Originally Posted by newhaul

My 2 cents worth is use a baja filter .



https://harborshoppers.com/baja-dies...diesel-filter/



For the rest a 10 micron racor centrifugal primary is plenty for me but my mitsubishi has a 5 micron onboard combined in the electric pump housing which then goes to a 2 micron that feeds the injection pump.



Main is the Baja stops the dock crud and water from questionable sources .

Your 2 cents worth is very valuable information, the Baja filter is a great help if you need to refuel from jugs and the only downside is how slowly the fuel drains into the tank. I couldn’t find the particle cutoff size of the Baja screens with a quick google search but I suspect 50-80 micron[emoji848]

[newhaul]

Originally Posted by skipperpete

Your 2 cents worth is very valuable information, the Baja filter is a great help if you need to refuel from jugs and the only downside is how slowly the fuel drains into the tank. I couldn’t find the particle cutoff size of the Baja screens with a quick google search but I suspect 50-80 micron[emoji848]

Iirc it was 30 micron and caught most of the water. But most importantly it allows you to see and smell the diesel before you pollute te tank. Fuel has to much water or bad smell stop and find a better fuel dock

[desodave]

If the fuel or tank is dirty a 2m filter will plug up quickly and at the worse possible time, probably in heavy weather. Rough water will stir the tank and raise the crud off the bottom. Not the time you want to do a filter change. In that case I'd go with the courser primary. The downside is you then have to change both filters every time.

This was my problem when (accidentally) running a 2 micron primary on our previous boat. All the crud gets caught in one filter which then plugs at a very inconvenient time. Cleaned some crud out of the bottom of the tank and switched to a 10 micron primary ... no more problems although I'm sure the cleaning also helped a lot in eliminating the problem. The loss of engine power was very unnerving ... returning to our marina in a relatively narrow channel with wind against current.

[FPNC]

Originally Posted by skipperpete

Recently a friend of mine had a serious diesel injector pump failure (seized hydraulic head on Perkins 4-108 DPA injector pump)

What was the actual cause of the injector pump failure?

[skipperpete]

Originally Posted by FPNC

What was the actual cause of the injector pump failure?

The rotor seized solid in the hydraulic head, usually this just snaps off the rotor inside the pump housing but on this occasion the splined drive snapped off in the timing gear leading to a lot more work before installing a rebuilt pump and splined drive.

[Mickeyrouse]

Filters will drive you crazy. We use a Racor 2 micron going to the engine 70 micron secondary- until our filter deale said, “throw that 70 away, it’s just a waste of time.” Which I did, 13 years ago. Still waiting for problems. But I do add Biobor, or Ward’s, anything to kill the critters.

[thinwater]

I know all about diesel storage and testing (refinery engineer). What I do NOT understand is the frequency of stories about "old fuel."


You change your oil every year. Why would anyone expect uncared for diesel to last longer without trouble? Use it. Pull it out and dispose of it. Give it away. But if you leave it in the tank for years, well, the prevention f your problem was obvious. You either need to change it by using it, or you need to care for it at a level that very few occasional boaters will (no copper fittings, very dry tank, silica gel filter on the vent, no filler leaks). Yes, copper and brass promote sludge formation and they are prohibited by ISO, API, ASTM, and all engine manufacturers for stand-by generator service ... which is what this is if it takes years to burn the fuel. Look it up.


Fuel polishing and double 2 micron filters are bad answers for what is nearly always preventable problem. Don't use old fuel.



Rant over.

[newhaul]

Originally Posted by thinwater

I know all about diesel storage and testing (refinery engineer). What I do NOT understand is the frequency of stories about "old fuel."


You change your oil every year. Why would anyone expect uncared for diesel to last longer without trouble? Use it. Pull it out and dispose of it. Give it away. But if you leave it in the tank for years, well, the prevention f your problem was obvious. You either need to change it by using it, or you need to care for it at a level that very few occasional boaters will (no copper fittings, very dry tank, silica gel filter on the vent, no filler leaks). Yes, copper and brass promote sludge formation and they are prohibited by ISO, API, ASTM, and all engine manufacturers for stand-by generator service ... which is what this is if it takes years to burn the fuel. Look it up.


Fuel polishing and double 2 micron filters are bad answers for what is nearly always preventable problem. Don't use old fuel.



Rant over.

Hence a diesel furnace it burns up the unused diesel from summer and I just refill every spring . But this year I'm watching for a short slump in the price.