Diesel Fuel Tank " Sludge "

[SimonV]

Tomorrow I will be cutting a hole in the sole and then the tank, needing to clean out a 30+ year deisel tank.

[mrohr]

I have always wondered why all the diesel cars and trucks don't seem to be plagued with this issue anywhere near as much as yachts.Any ideas?

FWIW: I change out primary filter at begining of each season,use a baha filter,keep threads of fuel fill lubed (sealed) with petroleum jelly EVERY time it's opened.I wish I had access to the interior of my tank,but that is not an option on my boat,I just monitor fuel bowl and carry spare filters.

I'd like to hear from others as to what their experience has been.

Problems seem to be a fuction of violent motion when in a seaway where sludge breaks free from tank walls due to sloshing . I suspect this sludge coats the interior of most tanks after a few years.

[SabreKai]

Originally Posted by mrohr

I have always wondered why all the diesel cars and trucks don't seem to be plagued with this issue anywhere near as much as yachts.Any ideas?

Think about it. A car or truck will drain its tank in a day or a week. Fresh fuel all the time. Our tanks may be filled in the spring, and still be half full in the fall. Lots of time for the grungies to grow and multiply. Plus we bounce around pretty good in a rough sea where as a car or truck may hit a patch of bad road once or twice a year.

[DeepFrz]

What I will do is come to you once your tank is full. The tank has to be full regardless of how much fuel is bad and how much is new, in order for all the baffles to be cleaned. I use a very good additive that breaks up the sludge which is actually algae and what this additive does is break the sludge from the walls of your tank as well as all around and breaks it down into smaller clumps of algae. We then proceed to run our system pulling fuel from your tank into our unique, one of a kind filtration system. The fuel then circulates through three separate filters and back into your fuel tank. Our machines picks up all the sludge and bad fuel, cleans the fuel of all contaminants, and returns it to your tank. After going over your tanks capacity several times, the fuel as well as the tank will be cleaned. And that's it. Simple yet 100% effective.

The above quote is from Ocean Side Fuel. It was sent to me as a PM but I am posting it here because the question was asked in the open forum and should be answered in the open forum.

Personally I don't believe that there are any chemicals that are safe for your engine that will clean a fuel tank, even those sections behind baffles. I guess I'll just have to be shown before I become a believer. That stuff needs to be scraped out or steam cleaned. It adheres tenaciously to the bottom and sides of a tank. I'm one of these guys that says "show me" if something sounds to good or seems to easy.

Sediment in fuel tanks is not all biological, possibly the majority of it is not biological growth. Lots of the sediment is tar like precipitates that form as a natural process as the fuel ages. You can tell if the gunk in your tank is biological growth or tar precipitate by putting a drop or two of household bleach on the gunk. If it turn white it is biological growth, if it stays black it is a tar like precipitate.

[Matt sachs]

This is the plan for my build. (and feel free to tell me its a crazy idea). I'm building 2-40 gallon day tanks. They will be in the salon somewhere. They have easy acess and polishers built in. However my primary tanks are in the keel and very unfun to gain acess to. The built in polishing system draws out of the very bottom of the lowest part of the tanks. Since they are in the keel and 100% underwater the daily temp change will be very little so I would expect condensation to be minimal. For long term storage I'm thinking about applying a slight vacume to the tank and closing off the valves. This should eliminate, or at least greaty reduce, condensation and alge growth. Am I crazy?? I plan on doing this to empty, or almost empty, tanks as they will hold a combined volume of 260 gallons and I don't think I will need them full very often.

[Freerider]

I filled my fuel tank with biodiesel, let it sit in there for a week, then pump it out into my furnace tank. The biodiesel dissolved the vast majority of the sludge build up. I plan on burning B5 - B20 in my engine when possible, that will keep the tank clean, plus keep my fuel lubricated.

I tried this originally in my 15 year old furnace tank and it worked great. I stayed on top of the filter changes and after 2 dirty filters, they always come out clean. The inside of my tank is now spotless.

[steve77]

I recently cleaned the fuel tanks in our 20+ year old Amazon prior to a trip from La Paz, Mexico to Houston. For all the obvious reasons, I did not want sludge fouling the filters. We bought the boat about 2 years ago from the original owner. She had not gotten much attention the last 10 years, and from the condition of the gaskets on the inspection ports, I don't think they had ever been removed.

My tanks are also baffled, and the inspection port only allowed access to the lowest point of the tank for cleaning. In my case, I was astounded when I removed the covers and found zero sludge in the tanks, and only a little grit. I had bought a case of paper towels to clean my four stainless tanks (total of 300 gallons tankage). I used a roll and a half cleaning out three of the tanks. The fourth was under the water heater, and based on the condition of the first three, I elected to forgo the process of removing the water heater to clean the last one.

I had a question on an earlier post. Why would you think 50 year old stainless fuel tanks would be at the end of their life? After 20+ years, mine still look new.

Also, I noticed the original poster made a statement about aligning his fuel return to a different tank than he was drawing from. In my opinion, this is a risky practice that can lead to overfilling a tank and a fuel spill (in my case) into the bilge. I had a mess to clean up after I found I had pumped about a quart of diesel into the boat. The smell of diesel alerted me before I pumped any more.

If you are going to return fuel to a different tank, I would be extremely watchful of fuel levels. I certainly would not do it as a standard practice when running the auxiliary.