Thread: Aux Tank Plumbing

I bought a Brown Davis Aux Tank from ebay. Its from a Tdi Defender & fits nice under the drivers floor & Electrics area. Fuel filler via a hole in floor using a marine cap thing.

Problem is I already have a Dolium 40 L sill tank that fits between the Fuel Filler Tube and existing Tank. Which means I dont have access to the Breather Pipes ect on the filler neck.

From the Top of the Dolium Tank there is a 20mm hose to the Breather on top of the original TD5 Tank

Any reason why I could not put a Tee in the 20mm hose to run my Fuel feed via a Transfer pump & Filter from the new 2nd aux tank & another Tee a little higher up to run my new breather to, basically breather & transfer filler going into the breather ontop of the TD5 tank.

idea being I'll only transfer fuel from the brown davis tank once the Dollium & main tank is getting low

Short of that I'll have to drop the Dolium Tank & weld a few barbs on.

ideas ???

sounds like about how I plumb in the aux tanks to the td5 tank which is more or less thusly

cut the breather line in 2 places as near to the filler and the tank as is achievable.


put the one that transfers the fuel from the aux tank to the main closest to the tank and in the lowest position. The breather line for the Aux tank plumbs in at the cut nearest (and highest) to the filler neck.

I like to try and use a Y pipe for the fill joiner nearest the tank. setup so that the fuel flows naturally through the Y towards the tank.