Do I need fuel polishing?

[Wayfarer]

That's filtering, not polishing. May do what you need still.

I'll be showing my ignorance here, but what is the difference? I always thought polishing was just an expensive way to say 'filtered.'

 

[BandB]

I'll be showing my ignorance here, but what is the difference? I always thought polishing was just an expensive way to say 'filtered.'

No, polishing involves the use of centrifuges or coalescers in addition to filters. It's designed to remove non-combustible contaminants while keeping the combustible ones so as not to degrade the fuel. The combustimble contaminants are then broken down and re-suspended. Here is one description of the process.

https://www.fuelpurification.com/

Most people will never need polishing. However, if your issue is fuel which has deteriorated then filtering will not do the job for you. You may get restarted but the fuel you're then using will not meet standards.

The most well known polishing system on boats is Alfa Laval but there are now other systems available.

 

[syjos]

I'll be showing my ignorance here, but what is the difference? I always thought polishing was just an expensive way to say 'filtered.'

True polishing is accessing the fuel tank via opening, sucking the diesel fuel out with a high capacity gear pump, or some other means, filtering it and spraying the fuel back into the tank via wand through the openings. The gear pump produces pressure that is used to spray the diesel out of the wand at high pressure, directed at the tank walls, washing any debris off the walls. The debris and the diesel gets sucked up at the lowest point and back to the filter and back to the pump.

Any stubborn debris is scrubbed with a brush or plastic scraper and washed to the pick up point.

The built in manufactured polishing systems picks up fuel from a port, filters it and puts it back into the tank via a port on the top of the tank. With high volume pumps, these polishing systems will keep your tank clean as long as you start with a clean tank and used frequently. I don't think these systems could remove debris stuck to the sides and top of the tank. There just is not enough agitation to unstick gunk from tank walls.

Some of the manufactured systems employ a "magnetic" device that supposedly explodes cells of living organisms. Voodoo magic?

Many of the owner installed systems are plumbed to pick up tubes that don't go to the bottom of the tank so questionable effectiveness. They are basically high volume circulation systems.

High end manufacturers will either offer a built in polishing system or will at least have ports on the tank in the correct locations to facilitate installation.

 

[Harlen]

Yes. All marine diesels that I’m aware of (which is few because I’m pretty ignorant) return fuel to the tank. Some like the engines that OldDan and I have, return a LOT of fuel to the tank.

Regardless, the unturned fuel that returns to the tank went through your primary and secondary filters. So over time,you will be filtering your fuel. So unless it is truly bad, it should be fine.

I’m still curious as to how many hours on the Racor filter that seemed black?

84 hours.

 

[angus99]

Note that there are numerous “commercial websites” that come up when you search for asphaltenes. They are trying to sell you something. Good and properly maintained fuel filters are all you really need. I opened one of my fuel tanks and while I found a few small back deposits, there was no water in the tank and no water in the Racor.

While we were on the loop but away from the boat, a diesel “expert” inspecting our Lehmans said we had fuel starvation problems due to clogged Racors and he would polish our fuel and flush our two saddle tanks for $1K. He presented a bill for close to $500 just for his assessment. Below was his evidence.

I told him where he could put his bill, changed the filter elements and we went on our merry way without problems.

 

[syjos]

Two fellow YC members had engines quit while crossing the Strait of Juan de Fuca. The wave action loosened the black yuck from the bottom and on one boat clogged the Racor. The other had the yuck clog at the tank outlet.

Both received expensive, emergency fuel scrubbing, requiring inspection plate installation.

Neither boat had selectable dual Racors. One boat lost both engines requiring a tow and the other one lost one and limped to port on one engine.

 

[dhays]

84 hours.

Thanks.

 

[dhays]

Two fellow YC members had engines quit while crossing the Strait of Juan de Fuca. The wave action loosened the black yuck from the bottom and on one boat clogged the Racor. The other had the yuck clog at the tank outlet.

Both received expensive, emergency fuel scrubbing, requiring inspection plate installation.

Neither boat had selectable dual Racors. One boat lost both engines requiring a tow and the other one lost one and limped to port on one engine.

I do like the dual Racors for that reason. I operate on one and leave the other as a “just in case” filter.

 

[ksanders]

What you need to do is drive your boat.

Burn some fuel, have some spare filters onboard of course, but run the boat more.

 

[dhays]

What you need to do is drive your boat.



Burn some fuel, have some spare filters onboard of course, but run the boat more.

+1

Harlem, I would also recommend that you get comfortable with changing the filters in the Racors yourself. Buy a half dozen of the filters and, assuming you have a dual filter setup, run on just one of them. Make sure you have a vacuum gauge on your fuel system so you can spot increases in vacuum (great thread on that recently).

 

[Simi 60]

No, polishing involves the use of centrifuges or coalescers in addition to filters. .

So 500 or 1000 series racors or their equivelants.

Stage 1 -
Separation: As fuel enters the filter assembly, it moves through the centrifuge and spins off large solids and water droplets which fall to the bottom of the collection bowl.

Stage 2 -
Coalescing: Small water droplets bead-up on the surface of the conical baffle and cartridge element. When heavy enough, they too fall to the bottom of the bowl.

Stage 3 -
Filtration: Water rejecting cartridge elements repel water and remove contaminants from fuel down to two micron (nominal). They are waterproof and effective longer then water absorbing elements.

The 1000FH takes 2020 elements, SM for 2 Micron, TM for 10 Micron & PM for 30 Micron.

The 500FG takes 2010 elements, SM for 2 Micron, TM for 10 Micron & PM for 30 Micron.

 

[FF]

"The other had the yuck clog at the tank outlet."

A common hassle, usually bug bodies and waste.

IF the pickup is removable it is sometimes possible to create a bag with lots of area out of metal and hose clamp it on the fuel pickup .

Recently the bride bought a fat splatter screen at IKEA , a couple of bucks , that has the finest SS mesh I have ever seen.

 

[OldDan1943]

Here is an example of a fuel polishing system.

Fuel Polishing System - 150 GPH - Separ - Marine

They make larger systems too.

 

[Wayfarer]

I'm told my new vessel has a fuel polishing system aboard, but I don't know anything about it yet. I'll add it to the very, very long list of things I need to learn more about.

 

[dhays]

I'm told my new vessel has a fuel polishing system aboard, but I don't know anything about it yet. I'll add it to the very, very long list of things I need to learn more about.

My guess it is a separate filter circuit run by a separate pump. There may be a long list of things to learn about, but how exciting is that!

 

[jimdavi]

Being new to diesel- quick question...
Will primarily cruise around home in the bay so wondering if I should fill-up (400 gal) and use during the year or fill less quantity and add fuel more often?

Thanks

 

[Harlen]

+1

Harlen, I would also recommend that you get comfortable with changing the filters in the Racors yourself. Buy a half dozen of the filters and, assuming you have a dual filter setup, run on just one of them. Make sure you have a vacuum gauge on your fuel system so you can spot increases in vacuum (great thread on that recently).

I am comfortable and do change the Racors myself, but once a year have the mechanic change the secondary fuel filter mounted on the engine as I am leery of that and don't want to spill fuel. I also have the vacuum gauge. However, having twin filters makes sense and I will pursue that.

 

[Harlen]

Also, the clear bowl in my Racor has had no water in it and is crystal clear with no sediment of any kind.

And it has never had anything in it other than clear fuel as I check it often.

 

[dhays]

Also, the clear bowl in my Racor has had no water in it and is crystal clear with no sediment of any kind.

And it has never had anything in it other than clear fuel as I check it often.

Sounds like you are good to go. I know what you mean about not wanting to spill diesel. I usually can find a way to make a mess when I do anything.

 

[Harlen]

Dave,

ValvTect Marine Premium Diesel contains BioGuard micro-biocide and is formulated to keep the fuel free of bacteria, fungi and algae that plug fuel filters, cause corrosion and can shut the engine down. ValvTect Marine Premium Diesel also contains ValvTect's Diesel Guard Heavy Duty Marine Diesel Additive, which prevents and cleans up injector deposits that cause loss of power and poor fuel economy. Fuel economy tests indicate improved fuel economy up to 13.6%. ValvTect Marine Premium Diesel also contains cetane improver, fuel stabilizer, lubricity improvers and moisture dispersant that prevents wear, prevents sludge and significantly extends the life of fuel filters.

See, this highlights my problem. I have only used ValvTect in the 13 years I have owned my boat, bought new. I just hit 2000 engine hours so use it a lot.

Given this, I can't understand why I have this problem.

But, with the much appreciated feedback form this forum, I will follow the advice given by several to add a biocide and then use the boat with lots of spare Racors aboard.

Thanks to all!

 

[FlyWright]

I do like the dual Racors for that reason. I operate on one and leave the other as a “just in case” filter.

I have dual Racors and on my setup and it's only possible to run on one filter element at a time. Are there other Racor setups that allow simultaneous use of both filters on one engine as opposed to one at a time with the other available as a backup?

 

[dhays]

See, this highlights my problem. I have only used ValvTect in the 13 years I have owned my boat, bought new. I just hit 2000 engine hours so use it a lot.



Given this, I can't understand why I have this problem.

I was wondering, since you are in Port Ludlow and the fuel dock there is a ValvTect supplier iirc. However, that is no guarantee that you won’t have a microbe problem, just much less of a chance. It may be that FF was correct and that it may just be asphaltines. Given your usage, the idea of buying less fuel more frequently may be a good option.

 

[dhays]

I have dual Racors and on my setup and it's only possible to run on one filter element at a time. Are there other Racor setups that allow simultaneous use of both filters on one engine as opposed to one at a time with the other available as a backup?

Yes. On mine there are 4 positions on the valve, Off, Port, Starboard, and Both.

 

[goboatnow]

Yes. On mine there are 4 positions on the valve, Off, Port, Starboard, and Both.

Same with mine - 4 positions. See pic... You can kind of see ‘ALL OFF’ stamped on the top, ‘ALL ON’ is stamped on the bottom

 

[syjos]

I have a dual Racor system with valves of my own design on Sandpiper. Single Lehman.

Each Racor can draw from either tank and return to either tank with two valves.

It allows Racor #1 to engine and Racor #2 to generator

By turning two valves, Racor #1 to generator and Racor #2 to engine.

Turn one valve and both Racors can filter to engine or generator.

Element can be changed with engine running, generator off. Or gen running, engine off.

Turn two valves and a circulation pump is in line to either circulate fuel or prime the engine.

Turn two valves and fuel can be pumped from one tank to the other.

I will take a picture when I'm at the boat tomorrow.

 

[BandB]

Are we even convinced you have a problem other than a dirty Racor? I'm not. Normally in that situation, we'd replace the Racor and see how it did with a new one. It may quickly turn bad again indicating an issue or go another 84 hours just fine.

 

[dhays]

Same with mine - 4 positions. See pic... You can kind of see ‘ALL OFF’ stamped on the top, ‘ALL ON’ is stamped on the bottom

View attachment 92762

I like the idea of putting that Velcro strap there. I’m going to steal it. Accidentally moving that handle isn’t a big problem, but it has happened.

 

[FF]

"Will primarily cruise around home in the bay so wondering if I should fill-up (400 gal) and use during the year or fill less quantity and add fuel more often?"


Do you use diesel for heat during the cool season?

 

[OldDan1943]

How much did/do you use last year?

 

[Ski in NC]

Original poster has been scarce with details.

How much fuel burned since filter was new. How much calendar time. Did engine starve for fuel, or was it just a black filter on change? What size filter? 500, 900, 1000?

Need those answered to determine if there is a real problem.

On my personal boat with 450 Cummins and 900 Racor, usually 10mic. Tanks have zero water in bottom (can see bottom through fill caps, shiny aluminum, no visible crud either). And still my Racor element looks black just like the OP's at around 100hrs. I notice it when at 1900rpm cruise, rpms start wavering a little. New element and rpm is rock solid again.

I think my black gunk is asphaltenes, and I worry not.

I'm not sure this guy has an actual problem.