Cleaning Diesel Fuel Tanks

[Charlie]

I've decided to cut access ports into my aluminum fuel tanks. From there I am going to clean my fuel tanks. Once I have access ports to each of the chambers what is the best way to clean the tanks. Ovioulsy we want to get the existing fuel out but from there what is the next step: My thought would be to scrub the tanks with a brush of some sort, then to sop up whatever I can with paper towels, then to vaccum the tanks out, and finally to use something like simple green to clean the tanks and finally to let the tanks dry out for a few days.
Questions I have are:
1)Is it Ok to use a nylon bush or will the diesel destroy it?
2) Do you think the shop vac will be ruined by vaccuming up diesel?
3) Is it ok to use a solvent like simple green or would you recommend something different.
4) Does anyone else have experience with this and/or can they reccommend a different way to clean the tanks?

[CSY Man]

I have cleaned my aluminium fuel tank 3 times the last 8 years.

The first time there was some sludge on the bottom.
I used paper towels, then windex and more paper towels.

No need for scrubbing or vacuming.
To pump the fuel out I used a hand pump one time and a hand drill with a $10.00 pump-attacment the next time.

Pretty easy operation if the tank is not too old or have been ignored for 20 or 30 years.

Some commerical services come around and suck up your fuel, run it thorugh a big filter, then use the filtered fuel to pressure wash the inside of your tank, then suck it up again, filter it again, and finally pump the fuel back in the tank.

The end result is clean fuel and a clean tank. I did that once and it cost $90.00 eight years ago. Figure $125.00 these days..(50 gallons tank)

Nowadays I save the money and do it myself with paper towels.

[hellosailor]

Charlie, can you physically remove the tank from the boat?

This makes the work MUCH simpler, and it means you can use a hose and detergent to clean out the tank, as well as the aluminum bits that may fall in while you are cutting the access ports.

I'm not sure about the shop vac, I suspect ignition danger (from the diesel fumes through the motor's brushes/sparks) if nothing else. We used Liquid Tide, which even dissolves Cosmoline, and warm water because we didn't have access to hot water. The nylon brushes are fine. If there are baffles in the tank--you may not be able to work around them. Removing the tank from the boat means at least you can roll/tumble the tank to get some action all the way around in it, repeat and rinse until clean. Then we gave it an alcohol wash (to help the water evaporate) and left it in the sun to thoroughly dry.

Would have taken it to a shop for steam cleaning with a "steam genny" but that would have meant a long trip and high price--the waste is hazmat. Working at the boatyard, it just went in the "used oil waste" tank. If you can rent a steam genny or hot water pressure washer, that's a good tool for the job.

[Charlie]

CSY Man:

I don't know if the tank has been cleaned since it was installed in 1985. The other thing I'm thinking about is that at the age of the tanks it might be a good idea to just replace the tanks. I'll be very curious to see what kind of sludge comes out of the tank. I did have the fuel polished previous to buying the boat.

HS:

Thanks for the good idea. I will take them out when I get home. Question is whether to replace them or not. Since I am planning on taking the boat to mexico and possibly beyond I might be better off replacing them. At the very least I can pressure test them to see if there are any leaks when I take them out. I have one of those tankless hotwater heaters in the house and a Sears pressure washer so I hot water wash won't be a problem.

[CSY Man]

Question is whether to replace them or not.

Nah, if the tank is good, don't replace it..

Spend yer money on rigging wire or steering cables or something.

[hellosailor]

Charlie, if there is no extensive pinholing, no corrosion on the welds outside, keep 'em. If you want to take extra steps to protect them, put some good epoxy paint on the exterior to prevent any more corrosion. There are interior treatments you can use as well--but unless those are applied perfectly, they can create problems too. Just keeping your fuel clean and dry will keep the interiors in good shape.

I've gotten a jones about not putting diesel in the fill spout until and unless I see it going in with my own two eyes, using a baja funnel or at least a big funnel with paper towels in it. I never want to argue with a diesel engine about whether it wants to eat what I'm serving for dinner again. Never. I'd rather stoke coal!

[gonesail]

if you are cutting new ports ... I recommend you take a look at the access plate product from seabuilt.com

[Charlie]

I looked at those Seaclear ports and they are expensive. Especially for what they are. The 6" ones are $138 each and I need 4 of them. I'm guessing for less than $100 and an hour or two of work I could make a square models of the same thing.

[DeepFrz]

Charlie, you are probably right about making your own ports (maybe an hour or two for each port). Just make sure that you use gaskets on both sides of the tank and that the bolts are welded to the inside piece. Diesel fuel will find the smallest gap to get out of the tank. With a square port you don't need to make them in two pieces as you can fit them in corner wise, but you probably already knew that. <gr>

[chuck711]

I've done quite a few Aluminum tanks lately and I cut typically 2 openings
in the top ( 4 X 4 ) hoping I miss the baffle plates (if it turns out it has one). Just enough to get my arm in. scrape and wipe the tar like stuff out.
rinse with mineral spirits a few times. Then with 1/8 thick aluminum stock I
cut 2 pieces 6 1/2 Square. Drill and Tap 10-24 threads ( 18 places )into the Tank and use a 6 3/4 X 6 3/4 Square Neoprene Gasket. Works very well. A good shop-Vac will be OK for diesel,holding tank stuff etc......