Cleaning Diesel Tanks

Hi I was wondering if any one could give me some advice as to the best way to clean 2No. 100 gallon diesel tanks.
The reason I ask is I’m looking into purchasing a 52ft ex-navy Pinnace which has been at her mooring in a harbour for 7 years with 1/2 the diesel left in the tanks. I have been informed that if I don’t clean the tanks, as soon as I put to sea the waves will stir up a sediment which will clog the filters, I was also told that diesel goes "off" if left for a long time.
I was wondering if the fuel leaves a "scum" on the inside of the tanks which will need scrubbing off or if I could just stir it up and drain the fuel out of the condensation taps? And if the old fuel could just be filtered and re-used?
I appreciate any help
Thanks Ed

 

If there has become anny water in the fuel it will soon become a place for bacteria to grow. They will create sediments and organic acids, sediments will clog your filters and the acids will harm your components.

Stir up the old diesel and drain it befour you use high preshure water.

I Would sugest after filling new diesel you should put in some tecnical alcohol and two-stroke oil. The alcohol will solve problems with wather that might be left in the tank and the two-stroke oil will add lubrication effect that the alcohol removed.
Condence remover can be used, but is aparetly not good for diesels.

I would higly recomend to take contact with drew marine or unitor to buy cemical's to add to the diesel witch will kill anny bacteria on your first filling in case there should be anny ******** left in the tank.

 

Ok smoke --did you get that. Actually if you google something like, diesel bug "cladesporium resinea" there is a lot of info on this. If you have inspection hatches then get the diesel out and scrub the tanks out the best you can with what ever you can. Clean the diesel before putting it back with a fuel polisher.
Again loads of info on these on google. Its just a pump that runs fuel through a suitable filter,- say 20 microns would be well good enough, especially when at the petrol station its only filtered to 50 microns. Or you might be able to get a pour in filter that does the job.

 

Unlike MR.Frost I will not recomend to reuse the diesel since bactereia(diselbug) will create organic acids. This is something you don't want in your diesel pump.

And after the tank is cleaned du yourself the fawour to poor in some cemcals from unitor or drew marine witch is poison that kill the microorganisms that is feeding on your diesel.

You can get the thank 100% clean by scrubing it, but why take the chance? Just spend a few extra dolar on some camicals.

If you know a engineer on a larger vesel he can probartly get you a litle in a botle.

 

Cladesporim resinae does not live in diesel --or water it lives in the membrain in between the two. Unless you are a ferry and burn the stuff every day its unlikely you will escape contamination of the dreaded bug.

Throw away 200 gallons of diesel?? Thats Eeerr,-- well whats that in uk now 1000 quid?

For 2 years I have a ton and a half on my boat . I am not going to drive around just to burn it off and I aint going to throw it away because it got some black bits in it!!

I am told ( web sites) that fuel addative is methonol alcahol ( methylated spirits in uk) and I am told that it is a corrosive for alluminium?

If you dont go very far, very often, you have no choice but to fit a fuel scrubber. Funnily enough I just fitted one this week. I believe in America it costs almost as much to dispose of the stuff than it does to buy it.

 

That sound exstremly strange to me. They have used methanol in racing and with those temperatures corroding would be acelerated and mathanol is closely related to ethanol with sweden now us as a 85% ethenol- 15% gasoline mix in there cars.

Are you shure about this???

I have experienced dieselbug first hand. We found out when we had to start to clean our fuel oil seperator more often and the filters.

Nasty stuff. We bought several cans off poison we pored into the diesel tanks.

I was motorman so I was charge off cleaning the seperators and the 1 engineer made me use rubber glowes after we started to use the cemicals since the stuff was not only harmfull to the microorganisms, but also to young motormens hands.

When we inspected the tanks some time later we found smal holes in the steel the tank was weelded out off. Corotion from acids that is a product from the proces that hapends when the fuel become bug food.

 

I have never heard that 'the bug " leaves acidic waste --residue or anything damaging. Are you not sure that it isnt the chemicals you are using to kill the bug that is damaging the tanks.

You say that cladesprium resinae is damaging to the pump even after a 50 micron filtration. I on the other hand dont like the idea of passing chemicals through it

 

50 micron filtration don't remove acids.

If you mix oil and watrer and let it stand for some time you will feel a horible smell from it.

Oil is only hydro carbones and h20

I would suspect that one off the acids forming in it would be H2CO3 (carbonic acid I think it's called) you have HC and H2O witch can form into CO2 and Hyrdogen witch smell nasty and from there CO2 + H2O ⇌H2CO3
I only learned that they can create acids, but I have no idea witch ones, but this one is my gues.

I would feel more comfertable about burning the diesel in a diesel burner instead off a engine.

I also had recomendations to change oil in the engine twice a year if you don't have heating on it while standing still. Condence in the engine oil can create acids that aparently is harmfull to the bearings, but I would not exspect the chance for that to be big.

 

Oh youve gone all technical on me there .I am not a chemist. I have not smelt oil and water? The diesel in my tanks smell the same as they always do---diesel!!

Yes you are supposed to change the oil even though you are not using the engine I have read that too,-- but I dont. A lot of peple start the engine and run it for 10 minutes and think they are doing good --I dont agree for a start off 10 minutes will not put back the power in the battery that it took to start it and will by way of internal combustion release acids into the oil. If you didnt start the engine you wont have a problem.

I never run my engine at all. I drain out the exhaust after a fresh water flush and I dont start it till I need it.

 

Jack,

Don;t you think it's a good idea to get lube oil pumped through the engine periodically even when you have no need of the engine? Ideally not just a start but a loaded run once a week or so?

 

It is true about the bacteria in the fuel, it'll eat through metal in the matter of time. For all the trouble worth. I would remove the tank and drain it out into proper refuse container, then pour in some clean coal oil, slosh it around somehow... you only need about a gallon of coal oil in that 100 gallon tank.. Pour that yucky stuff out. You good to go. I does this with my tractor when it was sitting for 15 years before I brought from a farmer.

 

52ft ex-navy Pinnace

Navy boats (in the USA) do not hace to meet USCG rulles , and frequently are far better for that.

Our 50f Navy Utility has a very generous fuel tank sump , with a valve that allows the bottom gunk to be removed.

Taking out the fuel and installing an after market access port (if none is installed) will allow you to really clean the inside if the tank.

Old fuel will have many ashpalt clumps , but these and any water will come out in a filter.
A Baja filter will do if its a by hand operation, but a Ray core 1000 with a 2 micron element and a large pump works even better. Nicest is if you perminantly install a polishing system , to circulate the fuel as needed.

The engine type will determine the need for extra polishing.

Old engines like Detroits (6-71 et all) and new commom rail engines ,will draw 35+ gph and return 90% to the tank.
A few hours in costal cruising will clean all the fuel by the multiple pass thru the filters.

Bosch and others setups (steel pipes to the injectors from the injector pump) return very little fuel to the tank , so will need more polishing.

FAST FRED

 

thanks for all your imput
fast fred, its a 1962 UK navy pinnace, the engine is a gardener sl 6 cylinder,
any idea how much a "Ray core 1000 with a 2 micron element" is?? or even a "baja filter" i looked at installing a fuel polisher and it was to expencive for me to buy.
could i use one of the filters you mention to filter and re-use to old fuel because as jack frost said 200 gallons of deisel is getting on for £1000 these days.
thanks

 

Hi Ed,

Have a read of these.

http://www.practical-sailor.com/sample/Fuelfilter.html

I think with a supply of clean (new) 200l drums, a small mechanical fuel pump, some hose, gloves, overalls and a sence of adventure - you can make a good attempt at cleaning up your fuel.

I would decant all your fuel out into drums (via the Baja type filter) and treat it with chemicals there and let them stand. Then pump the top 190l of each drum into another clean drum again via a baja style filter, before returning it to your tanks (yes, via the cleaned filter). Discard the dregs - Nov 5th!

Whilst the boat's tanks are empty I would get in and physically clean them. Navy vessels should have been built with access ports.

Make sure you have a pair of inline filters fitted in parallel close to the engine, ideally with glass viewing bowls. This way, if one blocks you can switch over to the other whilst you clean the first. The Racors are good as has been mentioned.

It's going to be a crappy job, but it's the most important thing you can do for ensuring your engine's reliability. Just look at the reasons for RNLI call outs.

Just out of interest, marine diesel is notoriously cruddy. Always try to buy from the outlet in your area that has the biggest sales, even if it costs more (at the fish docks?). Most recreational marine places run their stocks down towards the end of summer and their tanks sit quarter full with condensation streaming into the fuel. If you don't use the boat much in the winter, top off your tanks completely at the end of summer and try not to buy any more fuel until you are certain your local fuel barge has sold all his rubbish contaminated fuel to other people in the spring.

I always recommend people with yachts who only use a small amount of diesel (racing yachts for example) to buy their fuel at a road garage in jerry cans. Clean high quality fuel for these people is worth the measly extra paid in tax.

 

A Baha filter at West marine is only about $20 , plastic but it works.

ANY good fuel filter with a 2 micron element will work.

The Marine Raycore is really pri$y the almost identical truck model is way way way cheaper.

Even the old style "sock" filter can be used with a small auto 30gph electric pump to clean the gunk.
The sock filter is a 2quart glass jar with a cotton? mesh filter screen , gunk and water settle to the bottom.

FAST FRED