Aux tank for tow vehicle


I redid my aux tank solution a couple months ago. The solution I installed in 2014 was kinda lame. Was time to do it better.

You can find the same 20gal tank all over Amazon and ebay. Criticisms.

  1. The AL is pretty thin so you certainly wouldn’t want things to bang on it.
  2. I read some complaints re. the interior foam dissolving into gook. The complaints weren’t directed at my seller, but I figured that it was likely that everyone was getting the tanks from the same Chinese outfit. Maybe the problem with foam was just usage with gasoline, not diesel. Maybe the mfr had since fixed the foam problem. Since I couldn’t be sure I pulled the foam out.

I did a couple different plumbing ideas before settling on a solution. I’ve a mechanical valve and an electric valve in series. I worried about a scenario where the electric valve wouldn’t shut off, or I needed to replace the electric valve. So I put in a mechanical valve too. At one point I had quick disconnects both before before and after the valves, but I ultimately deleted those. The pic shows early plumbing so electrical valve not visible.

RDS has a kit that taps the aux tank hose into your filler hose. I put that in place 4yrs ago to support the previous aux tank solution.

The boards the tank sits on aren’t wood. They’re some kind of plastic “faux wood” from Home Depot. I wanted something that would stand up to water and diesel better than wood.

The fittings came from a local hydraulic repair shop. -10AN is the same as 10JIC. I adapted that to a 3/8" barb.

12V valve.

I wired it to an illuminated switch just under the cigarette lighter in the storage console.

On the rear left of the tank is the vent. I used a 10JIC cap, drilled a small hole, tapped it for a 1/4" NPT barb, and then used a short piece of rigid hose to attach a small checkvalve valve vent.

If I had a do-over, I’d look for a tank made of thicker AL.

Be advised that the laws for aux tanks are different for gas and diesel. I think for gas aux tanks you’re supposed to have a pump feeding fuel from the aux tank. Diesel aux tanks can be gravity fed.