Thread: TD5 Defender sill tanks

The following is a brief outline of the installation of a pair of sill tanks into a Defender, using the original fill point for both tanks. There is a pump on each tank to transfer diesel to the main tank. Total fuel capacity is now 187 litres (assuming 70l for the main tank) giving a comfortable range of in excess of 1200kms towing our boat. We have used these for quite a few kms and all works well.


I purchased the right tank on Ebay - I believe it is out of a TDi Defender. I had to relocate the fill point about 20mm lower to clear the TD5 chassis outrigger. Also replaced the breathers, fuel gauge and outlet. Finally the tank was coated internally with POR15 tank sealer. This tank holds 65 litres usable.

Right tank


The left tank was manufactured using the right tank as a template (thanks to Andrew) The top was adapted to clear the battery box. Finally the tank was coated internally with POR15 tank sealer. This tank holds 42 litres usable.

Left tank


I replaced the original TD5 plastic fuel filler with an earlier metal fuel filler. This required the enlarging of the hole through the body as the filler is slightly larger. The filler was modified to accept another fill point for the front tanks, also 2 breather positions and 2 fuel points to transfer fuel from the sill tanks. On the left in the photo below, is a standard filler. On the right is the modified filler.

It is possible to fill the front tanks separately to the rear tanks - by inserting the fuel bowser nozzle into the forward facing pipe. All the breathing from the tank is outside this area

Fuel filler


This flexible line was used in a number of places - it was quite difficult and expensive to source.

50mm flexible fuel line


The fuel filler after connecting - all good quality fuel grade lines. Breather 1/2 inch, pressure 8mm and fill 50mm

Connected fuel filler


The left tank is accessed through a pipe just above the chassis with a home made TEE piece. All rigid pipe is exhaust pipe, mig welded as required. There are 2 breather points at the high point of each tank. A breather from each tank is run all the way back to the fill point.

TEE piece across the car


The outlets are facing forward tucked up above and protected by the chassis out riggers. These were kept as low as possible to maximise the available fuel in the tank

Tank fuel outlet prior to pump


The fuel pumps are probably the wrong type for the application but they work well. They are actually pressure pumps. I have connected the suction line with 12mm (1/2 inch) line and the outlet with 8mm line

Fuel pump


Fuel transfer is done from the dash by the 2 switches at the upper left of the dash. The left switch transfers fuel from the left tank and the right from the right tank. A have yet to install a digital readout for the 2 tanks . This will be located immediately under the radio. I am currently working on the fuel gauge display. It takes about 30 minutes to empty each front tank.

Dash switches

Originally Posted by Bundalene

This flexible line was used in a number of places - it was quite difficult and expensive to source.

50mm flexible fuel line


The fuel filler after connecting - all good quality fuel grade lines. Breather 1/2 inch, pressure 8mm and fill 50mm

Connected fuel filler


The left tank is accessed through a pipe just above the chassis with a home made TEE piece. All rigid pipe is exhaust pipe, mig welded as required. There are 2 breather points at the high point of each tank. A breather from each tank is run all the way back to the fill point.

Bundalene

Great post.

The flexible fuel line would you mind letting me know where you sourced it.

Also the two red hoses am I correct that these are the breathers in which case I’m curious as to where you plumbed in the lines from the belly tanks to the main