Adding a side tank to a 110

The reasoning behind fitting a side tank was to remove the need to carry jerry cans when on safari in Africa. Fuel wasnıt a huge problem in Morocco but when venturing into the Sahara the extra range/ emergency reserve is very important. Fuel on the roof rack overloads it and can make the truck unstable and cans of diesel in the vehicle are smelly and inconvenient.

I opted to go for a 90 tank mounted under the drivers seat (right hand side). They hold 65 litres of fuel giving a total capacity of 145 litres and an on road range in excess of 800 miles. I wanted to use as many standard parts as possible, preferably good condition second hand parts, theyıre plentiful in GB.

After much thought I decided to cut a hole in the side of the body and use a 90 style filler as opposed to a series style filler cap. There is less cutting of the body with a 90 style filler, one hole in the side on a flat section as opposed to a hole on a curved section and a second hole through the wheel box which would need a cover fabricating to protect the filler hose on the inside of the vehicle.

The 110 has a small storage box under the driverıs seat, this would have to be removed to fit the tank. I found a second hand 90 seat box for £10 which turned out to be a real bargain as the battery box was badly rusted on the 110. This saved having to remove the storage box from the 110 seat box assembly and repair the rusted battery box. All pictures of the fitting show the seat box removed for this reason.

The first task was to collect all the parts: 90 fuel tank with fuel suction, return and fuel sender units attached (second hand) 90 front tank mounting bracket 90 seat box (second hand) Facet fuel pump (second hand, left over from converting my petrol 90 to tdi power) fuel cap and filler tubes (second hand) assorted fuel lines (second hand from various scrapped 90s and 110s) a fuel gauge a second pair of fuel tank suction and return lines. Sorry there are no part numbers as everything was second hand.

The method I chose to transfer the fuel involved running the main tank to at least three quarters empty and then pumping fuel from the second tank into the main tank. This seemed the simplest method, avoided change over taps and didnıt compromise the main fuel system. The fuel is drawn from the side tank and fed into the main tank with a fuel return from the main tank to the side tank to hopefully avoid overflow as diesel can return to this side tank incase of the main tank being overfilled. The return pickup pipe in the main tank was cut short to avoid any siphoning between the two tanks.

The first task was to fold up the body recess to locate the fuel filler out of a sheet of aluminum. Then there was nothing else for it , major disassembly would have to start. The seat box was removed without problem. The gearbox and transfer box were removed for overhaul at this point. The first bodywork to be cut was to allow the tank filler and vent to pass through the bodywork below the seat box. The tank could then be offered up and two holes drilled in the cross member at the back of the tank to allow the tank to bolt up at the back, visible in the previous picture. Two 5mm spacers were needed between the rear of the tank and the cross member The front of the tank is supported by a bracket, the holes were already in existence on my chassis and simply bolted up with 3 M8 nuts, bolts and washers. That was the tank mounted.

The fuel pump was mounted under the seat box close to the side tank to keep the length of fuel line under suction to a minimum. A small bracket was fabricated from 16 gauge sheet steel to mount the fuel pump on existing holes in the chassis.

Fuel lines were runback to the main tank. The main tank then had to be drained and dropped out to allow the fitting of the fuel in and return lines to a pre-existing blanked off hole. The hole accepted a standard 90 fuel pickup pipe (shortened) with a fuel return to the side tank mounted on top of that.

The next step was to cut a large hole in the side of the body for the fuel filler. I luckily had a 90 to measure carefully. The hole needs to be as close as possible the top of the wheel box and rear bulk head allowing space to rivet the recess into position.

Finally wires were run for the fuel gauge and fuel pump. An illuminated switch was used to operate the fuel pump. The pump canıt be heard running while the engine is running despite not being rubber mounted.

All that remained was to refit the gearbox, transfer box, overdrive, seat box, floor and seats, that was about a weekıs work.