Diesel Polishing

[sailah]

I built my own from a Carter P4070 fuel pump and 2 Shelco FOSBN78 filter housings. I paid $14 for the SS filter housings on eBay, the pump was $60 and the 5-10 micron filters (which are WAY bigger than a Racor) are $5. Everything else is random plumbing parts.

It all worked great except 1 major issue I caught early on. You cannot pull fuel from the engine pickup tube as it will starve the engine. I wired it up with a 2 way switch to run either when engine is running or manually. I always run it when the engine is on. Pump is rated for 72 GPH but clearly it can't do that with all the plumbing and filters. I have the pump in between Filter 1 and 2. Filter 1 is 10 micron, Filter 2 is 5 micron. The 2 filters are way overkill.

I used to have a dirty Racor at the end of every season, now they look like new after a season.

[Knock-on]

So, basic design is attached. Going to do two benchmark tests with the separator filters using a CAV296 and a RACOR 120 and a cheap inline fuel filter for primary. Fuel pump is low flow (60l/h) which matches both secondary filters.

For Tests will be using 2x20l Jerry cans one filled with new fuel and a controlled amount of contaminates and sea-water and will report back in a few weeks with the results.

[svspirited]

Pretty much what a64 said, the engine will polish the fuel over time. Better than having a separate polishing system is to have a dual filter setup on a manifold so you can switch between the filters, one gets gunked up you can switch over to the other without missing a beat. I have this setup along with a polishing pump that I sometimes run while sailing in rough seas when all that gunk is getting kicked up in the tank. Then when I go to switch the engine on I switch to the "clean" side of the manifold so I know, at least in theory, that clean fuel should be going to the engine without concern for things getting fouled up at exactly the wrong time.


This is accomplished through a Racor dual filter manifold connected to a three way valve which connects to a Jabsco Vane Puppy pump to push the fuel through. This has worked well for me for the past two years though it may be a bit of overkill for your situation.

[sailah]

A couple other benefits to standalone polishing systems:

-Mine can operate as a backup fuel pump. I valved in such a way that I can bypass the stock Racor and deliver 5 micron filtered fuel to engine secondary. Covers me for a clogged Racor or failed lift pump. And since it has a separate standpipe for pickup, a clogged pickup tube too.
-Allows me to pump out all fuel of the tank in case of contamination

[a64pilot]

Curious, how many of you have ever gotten even a single drop of water in the bowl of your Racor?
I did once, on my Brothers boat, in fact we got a lot of water, had it professionally polished and later we got more water again, turned out to be the o-ring in the filler cap, I don’t remember if it was missing or just bad, but when it rained a lot of water would flow down the deck, and a LOT got in through that cap. We first thought it was the vent positioning, that water got in there in a rough seaway, but that wasn’t it.

But in I guess the five years we have owned this boat, I have never, ever gotten even a single drop of water.

When I bought the boat there had obviously been a “bug” infestation that had been killed, on delivery several times the fuel line right in the 90 degree elbow at the top of the dip tube, where the shutoff valve is located would clog what looked like Tofu, this happened several times, but of course has since gone away. Interestingly the filter stayed clean. It was in chunks.
I never add fuel without Biobor JF, even if I buy Valvtec fuel, which has a different but pretty effective biocide in it already, they are the only US distributor that I know of that adds a biocide.

I have the dual Racor set-up, and have never needed it, the only time my engine has had fuel starvation from a filter it was the engine mounted one, which I now change with the Racor to keep that from happening again, but anyway we motor most likely at least as much as most, and I change the Racor every other year and have never clogged one.

If I were clogging filters then I guess I’d see the need fo fuel polishing, but I don’t so I don’t.
But then in a sort of fleet of farm tractors and trucks though out my life, we never, not even once had a fuel problem.
Assuming .4l per min, my engine recirculates my whole fuel tank ever 5 hours, assuming it’s completely full, so .4L a min isn’t trivial. If you only carry 50ish gl of fuel.

As far as a fuel pickup, there are two schools of thought there, have it a bit off the bottom so it doesn’t pick up trash, and have it right on the bottom so it picks up any trash that is there.
I’m in the school that says have it right on the bottom, that way it never builds up, but is sucked into the filter right away.

[Bill O]

Originally Posted by Knock-on

So, basic design is attached. Going to do two benchmark tests with the separator filters using a CAV296 and a RACOR 120 and a cheap inline fuel filter for primary. Fuel pump is low flow (60l/h) which matches both secondary filters.

For Tests will be using 2x20l Jerry cans one filled with new fuel and a controlled amount of contaminates and sea-water and will report back in a few weeks with the results.

Is there a reason you keep referring to the water that may be in the fuel containers as "seawater"? Would expect the water to be condensation from the atmosphere (fresh water) unless you had a deck leak or a poorly positioned vent that allows in sea water.
While not normal/very rare, have seen fuel tanks collect so much water (from unknown sources) that it fills the Racor bowl w/water.

[a64pilot]

The source of most water in fuel is not condensation, it’s actually from the fuel itself, at least for aircraft and Jet fuel and Diesel is similar.
Anyway fuel will absorb a surprising amount of water and temp changes may make this water come out of suspension.
In the Military before we could refuel aircraft we had to run an “Aqua Glow” test which determined the amount of fuel in the water, if it was too high then we would have to recirculate fuel though a trash can sized filter that contained a water absorbing material, I believe but am not sure it was the same or very similar stuff to what is in baby diapers that absorbs water and turns from a granular dry material to a gel.

Racor filters I believe have a water absorbing material and will clog up if enough water hits the filter media.

https://www.gammontechstore.com/Prod...Code=GTP%2D322

The French test fuel with a small bottle and a small amount of powder in it, they put in fuel, shake it and I assume look for a color change. I didn’t speak French so I never found out, but they would show me the bottle expecting me to know what I was looking at, which I didn’t.

Anyway I’ve never gotten any water to come out of suspension on my boat and I assume that is because the tank temp is very stable, it follows water temp closely, but when motoring it heats up quite a lot. I assume it takes colder temps to make the water come out of suspension.

[darylat8750]

I got bad fuel in Mexico once. It was UGLY. I filled up Racor 500s in less than a 1/2 hour. Fuel pick up is about 3 inches from the bottom of the 275 gallon tanks. I pulled the plug on the bottom of the tanks and the first couple of gallons that came out didn't even smell like fuel. I did the whole pump out, clean routine. A couple of years later I pulled the bottom plugs again and got a little crud out. I built a system similar to Jedi's with a Racor 900 I picked up off Ebay. I also like the ability to use the polishing pump to prime the double Racor 500s after changing them. No need to fill the bowls before putting the new filters on. Just leave them a little loose and flip the switch until full.
Running the polishing system while running into a steep 3 or 4 foot chop I think probably gets anything that is not really glued to the tank walls stirred up enough to filter.

Now I try to buy fuel where commercial fishermen or ferries fill. High probability that the fuel will be fresh and clean.

[Bill O]

Originally Posted by a64pilot

The source of most water in fuel is not condensation, it’s actually from the fuel itself, at least for aircraft and Jet fuel and Diesel is similar.
Anyway fuel will absorb a surprising amount of water and temp changes may make this water come out of suspension.

Racor filters I believe have a water absorbing material and will clog up if enough water hits the filter media.

My general term of "condensation" wasn't just what was formed on the tank walls, but included hot humid atmosphere absorbing into the fuel, then dropping the suspended water out w/cooler temps. Really just splitting hairs as it all potentially adds to water to the bottom of the tank.

Just for clarification, the Racor filters have a chemical added to the filter to repel water.

[Bill O]

Originally Posted by darylat8750

I got bad fuel in Mexico once. It was UGLY. I filled up Racor 500s in less than a 1/2 hour. Fuel pick up is about 3 inches from the bottom of the 275 gallon tanks. I pulled the plug on the bottom of the tanks and the first couple of gallons that came out didn't even smell like fuel. I did the whole pump out, clean routine. A couple of years later I pulled the bottom plugs again and got a little crud out. I built a system similar to Jedi's with a Racor 900 I picked up off Ebay. I also like the ability to use the polishing pump to prime the double Racor 500s after changing them. No need to fill the bowls before putting the new filters on. Just leave them a little loose and flip the switch until full.
Running the polishing system while running into a steep 3 or 4 foot chop I think probably gets anything that is not really glued to the tank walls stirred up enough to filter.

Now I try to buy fuel where commercial fishermen or ferries fill. High probability that the fuel will be fresh and clean.

This is exactly why I like to take a sample of the fuel and look at it in a clear glass jar before the "purchase".

A Baha filter or even the WM type water repellent fuel filters are very good at removing the xs amount of water and junk before it goes into the tank. It does slow down the fueling process, but IMO saves time in the long run.

[artisanmach]

Won't a UV light in the polishing system kill the bugs? at least the ones that pass thru it?

[artisanmach]

Like this one

https://www.cleanwaterstore.com/mm5/...WS/PC-6_UV.jpg

[Group9]

When I took our diesel tank out to fix a leak (aluminum, 20 years old) and pressure washed it, I was suprised to see lots of stuff that looked like cooked spinach coming out of the tank, that had been stuck to the walls and bottom. I mean, a lot. And, we really weren't having a lot of fuel problems. Polishing sure would not have got that out, and we were using biocide.

[noelex 77]

Originally Posted by Group9

Polishing sure would not have got that out, and we were using biocide.

A boat installed fuel polishing system will not clean a very dirty tank, but I think it can at least help prevent the tank becoming dirty in the first place.

A boat diesel tank that only needs cleaning out every 20 years is doing well and indicates good fuel practices and probably is indicative of cruising areas where good quality fuel is typical. The interval for full time cruising boats is more commonly 10-15 years and this time seems to be becoming shorter, perhaps due to a combination of more bio diesel and modern engine designs that demand cleaner fuel for reliable performance. Occasionally there are reports of relatively new boats that develop severe tank contamination from presumably taking on fuel with a diesel bug problem where the added biocide was not effective or the resulting dead biomass causes significant problems.

Cleaning the tank is a messy job and unfortunately the current practice of only a small number of access hatches can prevent reaching large areas of the tank. Areas hidden behind baffles cannot be cleaned. This makes it impossible to do a satisfactory job without major surgery.

There have been no controlled studies, but my feeling after talking to many cruising sailors is that a regularly used polishing system combined with other sound fuel practices eliminates or at least greatly increases the time between the need to perform routine tank cleaning and significant improves the chances of controlling a diesel bug problem.

Keep in mind that the ultimate aim is not just to have the cleanest fuel tank, but to keep the engine running reliably in rough offshore conditions when any debris will be stirred up.

We have six large access ports (4 are shown in photo below) for our fuel tanks, which will make cleaning of the tanks relatively straightforward , but I would still rather delay or preferably permanently postpone the task.

[a64pilot]

Originally Posted by artisanmach

Won't a UV light in the polishing system kill the bugs? at least the ones that pass thru it?

No, and even if it did you still have the dead bodies that will clog filters etc., plus they are still growing in the tank, and that’s the problem.
They don’t often live out in free fuel so to speak, but form a bio-film and attach themselves to the surfaces of the tank. Eventually of course some break off or die and fall off the tanks surfaces and clog the filters.
It’s really exactly like the slime that will grow in your fresh water tank and lines, it grows on the walls of the lines and tank, you only see what breaks off.
Mu opinion from dealing with the exact same thing from aircraft is prevention, not cleaning up, but preventing, and that means a good biocide and maybe twice a year shock levels, shock it if you know you will be dock sitting for a while.
Realize 32 oz of Biobor JF will treat 2560 gls of fuel, half that at shock levels. So one quart per 2,0000 gls of fuel say. How long does it take you to burn 2,000 gls of fuel?
I keep a baby bottle to measure the Startron and add the Biobor. PS says Startron helps stop fuel tank corrosion, I don’t know, but trust them. I know it has almost stopped my smoky Yanmar and greasy stern, which a Cetane improver also did, so I believe it is a Cetane booster.
I found out my Yanmar requires a min of 50 Cetane, and not much US fuel meets that spec, the higher the Cetane the easier it is for the fuel to combust and it burns cleaner too.

I don’t believe I have ever gotten any BioDiesel, I don’t think it’s common for Marine fuel, not in the US, or I don’t think so anyway, I believe they have to label it?
But it’s coming, and depending on what the Bio is, it can be bad about growing bugs, there are several very different forms of Bio-Diesel, the stuff from filters French fry grease is very different from the stuff from plants as the French fry grease may be animal fat, or maybe not.

Only thing I have ever seen in my Diesel tanks before is called Asphaltanes, which is exactly what it sounds like and it will often be dissolved into some fuel and deposited by other fuel, so it can sort of come and go.
Fuel is of course a solvent and can dissolve asphalt. Pour some on your asphalt drive way if you don’t believe me.