4WD MODIFICATIONS - STORAGE
Very few 4WDs leave the factory with sufficient fuel tank capacity for extended Outback trips. Unless you have 140-litre diesel tank capacity you won’t have sufficient fuel for long bush trips.
Today, the only 180-litre standard-tank machines are LandCruiser 70 Series Troopys and dual-cab utes, so they need no capacity enhancement. But even 180-litre tanks aren’t enough to fuel a petrol engine for hauls such as the Canning and the longer Len Beadell desert tracks.
All other 4WD utes and wagons have insufficient capacity for Australian Outback distances, where the general rule of thumb is that you need around double the capacity of the standard main tank. Even two-tank Patrols and LandCruiser 80,100 and 200 Series are a tad underdone, because their auxiliaries are around half the size of their main tanks.
The best arrangement for increasing fuel tank capacity is the way Toyota has done it, using two separate tanks and supply systems. That method means duplicated tanks and fuel lines, so if something goes wrong with one tank you can rely on its fully-functioning partner.
However, few vehicles have enough under-chassis space to accommodate twin tanks, so the next best is a replacement tank for the standard one, with up to double the original’s capacity. The other option is an auxiliary tank that pumps or drains into the main tank.
After market tanks
The standard tanks fitted at 4WD factories are formed from pressed steel or moulded plastic and are designed to be produced in their thousands and to be fitted quickly on production lines. You can look at most fuel tanks and see the amount of wasted under-floor space there is beside, above and, sometimes,
After-market tank makers look at the wasted space and endeavour to fill as much of it as they can with tank volume.
An after-market tank is quite differently made from the standard pressed or moulded types and would not be economically viable in a mass-produced vehicle plant.
Most after-market tanks are made up from pressed-steel pieces that are welded together. The most common material for after-market tanks is zinc-plated or aluminised steel plate.
When you’re shopping for an after-market fuel tank it’s important that you buy from a reputable maker who backs his products with a warranty and who has established service points around Australia.
The tank needs to have fuel-surge control – usually done by the shape of the tank and with internal baffles. For off-road use it’s essential that the fuel pick-up is in a retention chamber that prevents fuel starvation when the tank level is low.
A replacement after market tank should use the standard fuel pick-up module and be easily recalibrated at fitting time so that the standard fuel gauge indicates the new-tank level. Fuel expansion capacity needs to be inbuilt and the drain plug must be easily accessible and be protected from rock damage.
Ideally, the tank should fit without any modification to the exhaust system and it should have heat shields if it’s close to the exhaust plumbing.
Auxiliary after market tanks need the same structural qualities as replacement main tanks, but there’s the additional requirement of fuel filling and delivery to be considered.
The best auxiliary tank neck is one that’s siamesed into the original filler port, so there’s no bodywork modification needed.
If your aftermarket auxiliary replaces a smaller factory one the delivery module, lines and breather can be reused, but if it’s a new auxiliary installation you need to be sure that the fuel delivery system is reliable.
We’ve spent many uncomfortable hours repeatedly draining fuel from an auxiliary into a bucket, then tipping it into the main tank, after the failure of a transfer pump. Siphon transfers sound simpler, but can also give trouble. Make sure the auxiliary transfer system is a long term proposition before you buy.
By far the best known producer of replacement fuel tanks is Newcastle-based (NSW) LongRanger.
This company has been producing tanks for many years and uses state of the art laser cutting to ensure absolute precision in tank construction.
LongRanger tanks are available for all popular 4WDs.
AT OTA, we’ve used LongRanger tanks in all our bush expedition vehicles and have never had an issue with them.
Our latest acquisition is a 160-litre replacement for our 75 Series’ rear tank. Rather than replace the now-leaking original Toyota tank we opted for a LongRanger replacement, boasting nearly twice the capacity as the original.
Lightweight long-range tanks
In late 2014 AutoXtras launched a growing range of lightweight, long-range fuel tanks, with capacities around 145 litres. The typical weight of a polymer tank is 19kg, compared with about 45kg for a steel tank.
The makers point out that polymer is the material of choice by vehicle manufacturers for original fuel tanks, because of less weight, no corrosion issues and greater impact resistance. Each polymer tank is a one-piece moulding, so there are no welds to crack and leak.
The AutoXtras tanks are Australian-made, using a blend of polymer materials that result in High Density Polyethylene (HDPE). This polymer blend has been designed for fuel storage.
AutoXtras tanks can be fitted using the original mounting points, so no drilling or modification of the chassis is required.
Interior fuel and water storage
Flexitank has expanded its 35-litre to 75-litre bladder-storage tank range to include newly developed collapsible tanks that can stow diesel inside a wagon or dual cab/extra cab ute.
Like Flexitank water bladders the fuel tanks stow in the back seat footwell.
The diesel Flexitanks are Australian-made from European and Australian polyurethane fabric, using a unique manufacturing method that allows for an inner liquid-holding bladder and an outer protective bladder. Both materials are heavy duty 1100gsm thickness, satisfying EPA requirements.
Flexitank’s diesel bladders have a 38mm x 200mm filler hose, with non-return valve, ball valve and dust cap. A 12.7mm delivery hose comes with camlock adaptors, a hand-pump rubber bulb and a two-metre extension hose, to allow fuel to be pumped from the bladder into the vehicle fuel tank filler neck. A folding flap on the end of the bladder covers the inlet and outlet plumbing and also serves as a drip funnel to keep any spillage out of the vehicle’s footwell.
Flexitanks can be rolled up when not required and avoid the need for the time and expense of fitting rigid after-market tanks. Flexitank stowage inside wagons or utes can be safer than using the jerry-can alternative and decanting the fuel is quicker and easier.
Flexible tanks are a viable alternative to metal long-range tanks, but don’t expect to save much money using this route: top-quality flexible tanks aren’t cheap, because they’re built to military specifications, for use as auxiliaries in aircraft, for example.
Portable long range auxiliaries
Jerry cans are still the most popular form of auxiliary tank, but they’re best kept for pure emergency conditions. It’s more space efficient
and safer to store 80 litres of fuel in an under-body tank than it is in four jerries.
Fuel stowed inside a vehicle has obvious primary and secondary safety issues.
Coping with extra weight
More fuel on board means more weight. It’s likely that if you’re investing in more fuel capacity you’ll also be fitting a water tank and that’s even more pudding. If you double the standard vehicle’s fuel capacity and, typically, slot in a 60-litre water tank you’re adding around 150kg to the vehicle’s ‘wet’ tare weight.
The tanks should be located as low-down as possible and the water tank as far forward as practical. It’s not wise to put both the additional fuel and water weight out behind the rear axle. If the long range fuel tank is offset to one side of the vehicle some balance can be restored by off-setting the water tank to the other side.
In any event, a 4WD that’s kitted up for long bush trips will most likely need after-market suspension and it’s best to present the tanked-up vehicle, fully loaded, to your suspension specialist.