Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting?

   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting? #1  

LanceH

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Location
West Central Ohio
Hey everyone.
I'm having a guy at work build me a diesel fuel transfer tank. Its 1/8" or .125 mill finish aluminum. Got three 4'x4' sheets at a scrap yard for $103. Its going to be 44" x 48" x 9" so it will fit below my crossover toolbox in the back of the Dodge. I sold my "L-shaped" 105 gallon tank because between my headache rack, fuel tank, and 27" wide toolbox, i just didnt have a lot of bed (its a long bed) left nor room for the gooseneck hitch.

So i thought that if I got rid of the L tank, scooted the toolbox back (giving me another foot of bed) and utilized the space under the toolbox, that things would be better. And I can only lose a little fuel capacity.

Anyway, my question is on the fuel 'fill/vent' port. Because the tank is shallow at 9" and i'm always driving on the construction site or fields or up/down steep hills, I need to have the fill port raised off the tank. At first I thought I'd put two 2" bungs welded in at opposites sided of the part of the tank that protrudes from under the toolbox. One would be for the pump and the other would have a 6 or 8" nipple extending up for the vent/fill cap. The only two options i've found are the copper colored cap that TSC sells or the older style cap that are on farm ground storage tanks. The latter of which isnt the best keeping sloshing fuel from getting out while the TSC cap is spring activiated.

I've noticed that RDS tanks have a plastic cap: RDS Auxiliary Fuel Tank/Toolbox Combo — 91 Gallon, Model# 72647 | Auxiliary-Transfer Tank + Toolbox Combos | Northern Tool + Equipment
Similar to one on your car or truck. My question is why can't I get a short 2" NPT nipple and a nipple with female "gas cap threads" on-then just weld the two together, thread the NPT end into the tank coupling and put the vented gas cap into the other? I guess my real question is what kind of threads are associated with gas caps, are they mostly the same, and where the heck can i get one?

I'd like everything to be aluminum to keep the materials the same. If i went with the TSC cap, it'd be steel and i'd have dissimilar metals. I dont want stuff sticking above the bed rails to keep the tank 'out of plain sight' by passers by.

Let me know if you all know of other caps or better ways i could build this thing. Thanks for any advice or help.
 
   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting? #2  
Cheap way out would be to go to a junkyard and pull the filler neck from an existing gas tank. Cut it to lenght you want to add, use two stainless steel hose clamps and a short aluminum nipple welded to your new tank. Connect the two pipes with a rubber hose. The disemilar metals won't be touching, due to the hose clamp and rubber hose. Another more expensive method would be to find a tractor trailer reefer tank and cut the aluminum neck off of one of them. However, they have a different thread than a standard gas cap. There are a lot of those tanks around, but will usually cost you around $50.
David from jax

Baffles? That sort of distance with a side to side turn can be hard on the welds of an aluminum tank with flat sides. Shouldn't take much, but I would add at least some. Might also consider dropping the filler neck below the surface an inch or so for stability, especially if you can weld it inside and outside of the tank (before it is assembled).
D.O.T regulations require tanks to be certified, so you might look into that before you get too far along(I see that tank cert on tanks of tractor trailers)
 
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   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting? #3  
I did a google search for 'aluminum fuel filler neck' and got dizzy from the results, your answer is likely somewhere in all that reading.... How tall a neck do you want?

I see some steel with a gasket at the bottom with the 6l small bolts to clamp the flange on so metal would not be touching, one even has a aluminum cap on it.

Others like are all aluminum. Many are from the racing world, specalty sizes, but see some standard stuff too.

--->Paul
 
   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting? #4  
I've bought brass before that have the four lead heat plugs in them and they're 2"NPT.
D.O.T regulations require tanks to be certified, so you might look into that before you get too far along(I see that tank cert on tanks of tractor trailers
)
Ditto here, the Vehicle Enforcement guys will pull you off the road unless it's a certified tank. We used to build our own (DOT mechanical shop) for different applications and had to quit......Mike
 
   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting?
  • Thread Starter
#5  
Cheap way out would be to go to a junkyard and pull the filler neck from an existing gas tank.... Another more expensive method would be to find a tractor trailer reefer tank and cut the aluminum neck off of one of them. However, they have a different thread than a standard gas cap. There are a lot of those tanks around, but will usually cost you around $50.
David from jax

Baffles? That sort of distance with a side to side turn can be hard on the welds of an aluminum tank with flat sides. Shouldn't take much, but I would add at least some. Might also consider dropping the filler neck below the surface an inch or so for stability, especially if you can weld it inside and outside of the tank (before it is assembled).
D.O.T regulations require tanks to be certified, so you might look into that before you get too far along(I see that tank cert on tanks of tractor trailers)

David-I thought about going to a junkyard buy the ones local to me only sell whole parts and no pieces-so i'd have to buy the whole gas tank. Which might not be that costly.
I did think about and looked on ebay for a 4" semi truck cap and fitting but think thats too expensive and too big.
I do have baffles going into it...8' worth.
DOT? heck, thats why i'm trying to half way conceal it!
 
   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting? #6  
7 or 8 years ago I built an aluminum farm gas tank. Posted the project on a welding forum, one of the members posted a link to a marine site that sold aluminum filler necks with caps. I didn't need it because I just went with a 1 1/2-inch aluminum pipe nipple and cap. I went back to that welding forum, but could not find the link. Maybe do a search for marine / boat fuel tank sites. I know they're out there, it's just using the correct terminology so a search engine will pick it up.
 
   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting? #7  
Try PVC fittings in hardware store. I would bolt 2" threaded flage to the tank and screw in threaded plug.
 
   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting?
  • Thread Starter
#8  
Try PVC fittings in hardware store. I would bolt 2" threaded flage to the tank and screw in threaded plug.

I dont want to use PVC due to being brittle in the cold temperatures.

Does anyone know if there are any metals i can mix with aluminum? :confused: Such as i may have an aluminum coupling for a tank fitting and wondering if i can use a bronze or brass plug without worry about dissimilar metals. I want a socket/hex style (female) plug and not the square (male) head.
 
   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting? #9  
I really have no idea, but I would think stainless might work, it is quite unreactive. I know gold would, but you wouldnt want to use that.
 
   / Homemade Aluminum Diesel Fuel Transfer Tank-Fuel Cap/Weld-in Fitting? #10  
I built a gas tank for a Greyhound bus turned camper, for the guy that owned the house where I now live. After he passed away, everything went up for sale at auction. I couldn't get the wife to let me bid on that bus (went for $7K). I asked the guy that bought it what he was going to do about that gas tank and he said it looked like it was store bought, so it would be ok. The cert plate was probably on the bottom... I told him it wasn't and he wanted to argue with me till I told him that I knew it wasn't store bought, cause I knew who built it.
Never saw the bus again, nor the owner so it must not have leaked (or maybe it did and all perished in the fire?)
David from jax
 
 
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