chlorox to clean diesel tank?

[renmihalov]

The algae got in the 12 gallon, 31 year old aluminum diesel tank of my CD27. I got the tank out--that's another story--and it's here at the house. Looking inside, there's a thin black coating on the bottom of the tank. If you scrape it with a long screw driver it scrapes off easily. I was thinking of putting a gallon of Chlorox in there and letting it soak for a while. But then I'm wondering whether the bleach might react with the aluminum and harm the welds on the tank--which appears to be in remarkable condition for its age.
I'm looking for suggestions on what to do now to clean this tank properly. I've got a power washer, but I am concerned about damaging the tube that carries the fuel to the engine.
Someone mentioned that EComponents provided them with a replacement fuel gauge. I'll try ordering one of those tomorrow. The cork on my original gauge is pretty blackenend, but it wipes off. New hoses and filters are on the way. But how do I get this tank clean without damaging it?

[Jim Davis]

I wouldn't use bleach or ammonia to clean aluminum. You could use acetone and slosh it around. Also many people will suggest a length of chain - it works, but will also leave metal particles in the tank that can lead to worse problems (electrolysis) when they react with the tank walls. There is no reason you can't use the pressure washer through the gauge sending unit hole and blast as much as you can loose. It is what I have done on mine. Then rinse with lots of water, let the tank dry in the sun for a couple days. After it is dried put some acetone in it, slosh and drain once more. Give it another day in the sun and reinstall it.

[John Stevenson]

Our CD36 had both a very dirty tank and dirty fuel when we bought it. We used Star-Tron Diesel Tank cleaner with very good results.

We added the cleaner to the tank (with the dirty fuel) and let it set for a couple of days. We then used a fuel cycling or polishing setup (borrowed from our boat yard) which allowed pumping the fuel through a large Racor filter and then back into the tank using a length of copper tubing - which allowed washing the sides of the tank (through the fuel gauge opening). We repeated this process 2 or 3 times and only had to change the filter.

We finally discarded the "dirty fuel" although it was looking a lot better.

Two seasons later the tank still seems pretty clean.

[tartansailor]

Looking at the MSDS (Material Safety Data Sheet) you will find that Startron is made up by combining VMP Naphtha and Isopropyl alcohol.

VMP Naphtha (any paint store) is an excellent solvent, and IPA can be purchased at any auto parts store under "Iso Heat"
A substantial savings.

I don't see harm in the CLEAN chain tank scrub. If one can abrade steel by swirling in a tank, than that is some powerful swirling!

Dick

[Ron M.]

since you have the tank out and determined to be in good shape consider installing an access port. It will make inspecting and cleaning easier in the future. There is a company that has them available,(can't think of their name-google it) or one can be fabricated as I did.

[renmihalov]

The access port idea is solid. It would be great to get your arm and rag inside the tank to wipe it down. But cost could be a factor. I would have to get somebody to cut the 6 inch hole, and that might not be big enough, and then I'd have to buy the port, and here's a good looking one with a good reputation, but about $160:
http://www.seabuilt.com/8plates.php

Is it a big deal to unscrew the fitting that carries the fuel out of the tank to the first Racor filter? I would think there's a 7 inch tube beneath it that should be cleaned? If I pressure wash the inside of the tank, that tube would be a casualty.

[Oswego John]

Steam works pretty good.

O J

[renmihalov]

After a few rinses with a hose, I'm seeing a fair amount of bare aluminum at the bottom of the tank. I put in some denatured alcohol which seems to be dissolving some of the black crud. I ordered 30 inch long tube brushes from justmanbrush.com in Omaha (prices seemed reasonable). I'm figuring I can get alot of the crud out with the denatured alcohol and the brushes. Then I'd probably finish off with a treatment of acetone and the brushes.

Now that I've been seeing in my web searches the troubles others are having with contaminated fuel, I guess my issues are not that bad. I could've probably gotten away for a few months with just a new filter.

I'd like to try the steam, but I really don't have access to anything like that. The Startron with the naptha seems like an additive to use while the tank is still in place. Believe me I will be using algae fighting additives. Biobor JF looks like a front runner for that job. But that might be for another thread--I'll search that.

[jcmacleod]

I took my tank (from a cape dory 27) to a automobile radiator shop and had it boiled out. Came out spotless and used a diesel additive ,biobor for algae for all fill ups and have had no problems for 10 years. Tank was very dirty when I originally pulled it out of the boat. While reinstalling tank , I added a fuel shutoff at the tank,replaced all hoses and added a racor filter to supplement the existing filter on the engine.

[renmihalov]

What a great idea to use a radiator shop! OJ was sending me in the right direction.
Anybody need some 30 inch long tube brushes? I can use the rest of the denatured alcohol in the on board stove that I've never used. (That coffee brewing thread really had me yearning to brew some coffee on board.)
Thanks for these wonderful solutions.
What would I need a tank cut-of valve for? When the filters get all clogged with algae waste, the diesel fuel isn't going anywhere.
Knock on wood that it's not a fuel pump problem behind all this. And if this works and the engine runs 30 minutes without stalling, I might even get my wife to come back on board for another sail and then I get to keep the boat for another year.