Understanding Diesel Fuel

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marinetrader

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Us trawler owners enjoy the sound of our diesels; like sweet music to our ears.* The diesel power plants are the heart of any boat.

Problems can take place with diesel fuel stored in your trawlers fuel tanks, affecting those diesels?

It is important to know what diesel fuel is to start with.* Diesel fuel is refined from crude oil. In petroleum refineries, petroleum is heated, and different hydrocarbon molecules are removed to create the fuel. Diesel is much thicker than gasoline and vaporizes much more slowly. It's often referred to as "fuel oil" because of its consistency.* Oftentimes forgotten, diesel fuel is an organic matter.

"Give a diesel engine clean fuel and it will run forever and a day." This past saying is less of an exaggeration than you might believe.* Repair statistics record that ninety percent of trawler diesel engine problems result from contaminated fuel. The hope of doing away with 9 out of 10 potential failures should put fuel-system upkeep at the top of your list.

The most frequent signals of fuel contamination in a vessel are blocked fuel filters, and decreased engine performance. Nonetheless, the absence of these conditions does not inevitably imply that your fuel is not contaminated. As a matter of fact, it is likely that every trawlers fuel is somewhat contaminated.* Fuel pick-up tubes, where the diesel engine pulls fuel from the fuel tank, generally sit about three-quarters of an inch off the bottom of your fuel tank floor. This location is intended to protect the engine from contamination that has settled to the bottom of the fuel tank. Therefore, you may never realize that you have a diesel fuel contamination problem until the fuel is disturbed in some way - such as when you are in rough seas in your trawler.

Moisture can get into trawler fuel tanks in different ways by condensation of wet outside air, during transportation from refineries to distributors, by leakage through broken fill hoses or vents and by careless handling. Water can create injector nozzle and pump corrosion, microorganism growth and fuel filter blockage with organic matter resulting from the corrosion or microbial growth. Your trawlers fuel/water separators should be inspected frequently for water and drained as necessary. In cold northern climates, ice formation in fuels containing water produces severe fuel line and filter plugging problems. Routinely getting rid of the water is the most effective way of preventing this problem; still, small amounts of alcohol may be used on an emergency basis to preclude fuel line and filter freeze-ups.

Regular diesel fuel filter changes and the expensive and time consuming project of cleaning diesel fuel tanks have become acceptable routine maintenance instead of looking for a warning signal for diesel engine failure. Fuel filter elements should last several hundred hours or more and injectors some 15,000 hours. Even so, since diesel fuel is inherently unstable, solid matters begin to form and the accumulating storage tank sludge will finally clog your diesel fuel filters, possibly ruin your injectors and cause diesel engines to smoke.

Diesel stored in trawler tanks for long periods (six months and more) demands specific care. This fuel suffers from multiple issues that affect its quality. The presence of free water supplies the medium for microbiological development that result in the formation of slime and acids inducing corrosion of metal surfaces such as storage tanks, pumps, injectors, etc. Left unattended this water layer will entrap sludge and become the breeding ground for microbes, fungus, yeast and more. This toxic mix produces acids that compromise the integrity of your storage tank, lines, pumps, fittings and worse, diesel machinery.

Another crucial agent leading to diesel fuel deterioration, is mechanical stress caused by heat and pressure of pumps. Since most diesel engines return considerable amounts of fuel back to the tank, it is easy to see that the engine itself adds to fuel deterioration.

Germs in the form of bacterium and fungus are present in all diesel fuels. Extended periods of fuel storage can make ideal opportunities for germs to grow in fuel tanks. The first suggestion of microbic contamination is mucous-like collections on fuel-filters. Bugs can only be removed from the fuel system by polishing or by preventing their occurrences by use of a diesel fuel biocide such as BioBor. I highly recommend it.

Should you use diesel fuel additives?* There are many of additives on the market today that are designed to improve the performance and efficiency of diesel fuel.* I prefer to use Marvel Mystery Oil.* However, if you use the right additives, you can reach peak performance from your fuel every time.

Most trawler fuel systems have primary and secondary filtering systems installed; Racor is a good example of primary filters.* Every time the engine is operated, the diesel is polished by filtering and returning fuel back to the tanks.* A separate polishing system can also be installed that polishes the fuel independently of the engine operating.
 
Bugs can only be removed from the fuel system by polishing or by preventing their occurrences by use of a diesel fuel biocide such as BioBor. I highly recommend it.

Practical Sailor would tend to disagree with your choice.

And polishing to be effective is a hugely expensive system to retrofit as the pressure and volumes moved are very large, if its to work.

The biggest hassle is most diesel boats are delivered with very poor ,impossible to maintain fuel tanks.

The TANK is the problem as the water interface is where the bugs grow , and most tanks are stuck with no way to clean them frequently.

This is because great maintainable tanks are 1% more costly , and owners dont demand them before accepting a new boat.

A "proper " diesel fuel tank has been in use* * since before the 1950's.

Ashphalting , the fuel clumping as it sits in a tank is easy to filter with the primary filter.

-- Edited by FF on Tuesday 23rd of March 2010 04:52:44 AM
 
I have customers asking for their fuel to be "polished' or "just pump it out and I'll replace it with fresh fuel". Both concepts I do not agree with; while both suggections are better than none, the real problem is what lies at the bottom of the tank. This is where the water gathers, then the bugs develop their little colonies and all heck begans.

If I cannot get to the bottom of the tank or behind baffles*with both my pump suction and pump discharge, then a proper tank cleaning will not take place. Most boaters will show me the deck fills when I come on board, this will 95% of the time not be feasible, we have to get our pipes into the tank.

After cleaning, I recommend a fuel additive that will address the water and lubricity. When you remove the water, you remove the food source for the bugs. The legal definition given is 'the fuel additive makes the bugs dead', by removing their food source. Last winter I had the pleasure of cleaning a 40 gallon tank on a 45 foot sailboat, very well maintained*and having a prood owner. He had been adding bio-cid for years and years, fuel was just as clean and healthy but at the bottom of the tank rested a layer of 'dead bugs', from the bio-cid.* I told him that to get rid of the moles in your yard you have to remove their food source, grub worms and the like. Therefore to get rid of ''bugs', remove their food source, water. Adding some bio-cids will treat, but not cure.

The lubricity in todays fuel is so lacking, to the point I add a treatment to all of my vehicles, both gas and diesels. The newer engines have fuel systems operating at such high pressures and close toleraces and by adding lubricity to them you are reducing downtime and costly repairs. As mentioned in an earlier post the older engines need addition lubricity to reducing downtime and costly repairs.

Sorry to rant on and on, but one more time, remove the water.


El Sea/L.C.

Suckin Sludge & Havin a Gas
 
the real problem is what lies at the bottom of the tank. This is where the water gathers, then the bugs develop their little colonies and all heck begans.

Yes , and a properly built tank , solves this problem!
 
"Yes , and a properly built tank , solves this problem!"

__________________
FF



And when was the last time we saw a 'properly built tank'? My Thompson has fiberglass tanks, one port one stb'd, with fuel feed connections as close as possible to the bottom at the lowest point - However there is still water, crud, micros and whatever else that goes on at night while we are asleep laying in there. Most tank builders will build a*rectangle or square tank, but not a properly built tank.

Somewhere way up high on the pecking order of life a group has determined what is best for us, so now we have no 'properly built tanks'.

So FF, when you heading* to northern latitudes?

El Sea/L.C.

Suckin Sludge & Havin a Gas
 
And when was the last time we saw a 'properly built tank'?

The last time you were onboard ant Navy boat ,

or on board a boat created by a NA that read Skeene's and looked at the Sparkman and Stephens tank setup from the 50's.

The ENTIRE hassle with fuel is from unknowledgable owners not demanding an extra $50.00 be spent on the new boat before accepting it from the builder!

FF
 

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