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Cleaning out fuel tank

4K views 16 replies 12 participants last post by  bwindrope 
#1 ·
My primary fuel filter recently clogged after less than 10 gals of diesel fuel passed through it, making me suspicious of the state of the fuel tank.

I have been scrupulous about where I buy my fuel, keeping the tank topped up, especially during the winter layup, and adding biocide with each fuel addition. But the POs of this boat may not (this is a charitable view of the POs :D ) have been so careful, so who knows what crud is at the bottom of the tank.

Is there a way to clean a diesel tank without removing it? I would REALLY like to avoid removing it. It is a real PITA job.

Thanks for any suggestions.
 
#3 ·
Unfortunately, fuel polishing will only get rid of the stuff floating in the fuel. It generally won't get the stuff that is adhered/growing on the sides of the tank. It is often that stuff that dies off or gets shaken loose in heavy weather and causes the fuel problems. Steam cleaning the tank is really the best idea if you've got fuel contamination issues.
 
#6 ·
steam cleaning



Can steam cleaning be done with the tank on the boat?

What access is required to the inside of the tank? There are no inspection ports on my tank. Just the fill, the two connections to/from the engine, the gauge, and the vent.
 
#4 ·
If you have inspection ports on the tanks and physical access, you can also empty the tank, remove the ports, and scrub it by hand.

Get it as clean as you possibly can, THEN do the fuel polishing thing. Properly done, fuel polishing nozzles are moved around the tank, squirting fuel on the tank walls during the polishing process. This helps to clean the tank walls, as diesel fuel itself is a fairly decent cleanser.

Thereafter, the biocide or other additive is a good idea, but the real solution is to install a fuel polishing system integral to the boat. Not hard to do, and it makes light work of keeping the fuel clean.

Bill
 
#5 ·
If it's an old tank all the money you spend on polishing, filters, and more it would be cheaper to change out the tank. (imho) REALLY! Been there done that! After agonizing over my tank that had pinholes weeping it came out in less then a hour! The new one is smaller and I can actually remove it myself without help now. 20mins.
 
#9 ·
most of those older tanks were aluminum I think.. mine was. thank you Sailor 50. I just don't understand how strongly people think they can "save" old tanks. New, off the shelf tanks are really quite cheap
 
#10 ·
You are right Denise, most of the tanks were made from aluminum, much less noble than stainless. We had a new one custom made out of stainless. When we pulled the old aluminum one out - it looked like swiss cheese! We can now visibly see the tank as we relocated it to a better site.
 
#11 ·
Last year I replaced a 32 year old steel tank that did not leak but was rusty on top from a leak around the deck fill - what idiot would put the fill in the middle of the cockpit well anyway? I replaced it with a stainless tank I had custom made to fit. And relocated the fill to the side deck with all new hoses.
Amazingly the old tank was not that bad inside but it's days were numbered.
 
#12 ·
I don't know why you'd want to remove it. I bought a 5" diameter high carbon hole saw and cut some inspection ports in mine. There were fistfulls of gunk. Polished it out with some elbow length chemical gloves and a toilet brush. If I had to do it over again I would buy hole saws that are the same size as pre-made inspection ports instead of fabricating my own from pieces of plastic HDPE and drilling and tapping new holes.

MedSailor
 
#15 ·
And don't forget a new o-ring on the fill. Far more common.

I think you'll find factory is generally silicone, if not a nitrile rubber gasket.
 
#14 ·
I had the same fears as you and so I recently had my tank cleaned. We have a fellow in my marina who's been doing it since 1976. He pumped out the fuel, cut 2 BIGA$$ inspection plates on the top on either side of the baffle and then hand-scrubbed the tank to a sparkling finish. I also had him put in a small screw-in plug so I can check the fuel level with a dipstick. Mine was all done in place, but the access to my fuel tank is absolutely superb. It's all going to depend on your tank location I think.

Mike
 
#17 ·
Since I did not recall the original post saying anything about leaking, and only about gunk, I agree with MedSailor that there are far cheaper and easier options to replacing the tank. I replaced the tank on my old Ericson 28 and so know of what I speak.

Another idea in addition to the cleaning ports mentioned above, is to purchase some B99 biodiesel and run that through. Make sure you have a good Racor primary filter (which you should anyway) and prepare to change it out a few times in the beginning. Also, make sure your diesel runs on the hot side, if it is fresh water cooled. A common problem is to have a thermostat that has her running at 160 or so, when the combustion temperature of diesel, especially biodiesel is higher and benefits from higher operating temperatures. I replaced the 160 stock thermostat on my Gulf with a 185 and greatly reduced the soot on the transom and did wonders for my engine.

Anyway, I ran biodiesel a while, replace a few filters, did a self polishing of opening my tank and agitating it while running the fuel pump through the filter and back to the tank, and now my tank and fuel system is so damn clean I replace my filters every year just for the formality of doing it. They are pristine after a long hard season.
 
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