THE AGE-OLD saying Ďyou only get out what you put iní couldnít be truer than it is with four-wheel drives. Want more capability? Put the parts in. Want more talent? Put the work in. Want to find yourself standing at the start of endless dirt roads and a thousand possible adventures? Flip your boss off, slap the credit card to the dash and head off into the sunset.

On occasion, however, the saying Ďyou only get out what you put iní can be a little too literal, and itís nowhere near as fun when that happens.

You see, like us specimens of male health here at 4X4 Australia, your 4x4 is a finely tuned machine. And just like we require a very specific diet of Friday beers and burnt campfire snags, your 4x4 needs an exact diet to stay fighting fit so itís able to take you on those previously mentioned adventures. In most cases the complicated engine control unit will keep everything metered spot on. The right amount of air, the right amount of fuel, the right amount of combustion - itís the perfect recipe to get you on the tracks. However, much like a peace-keeping mission in the Middle East, things donít always go to plan.

Over the next few pages weíll be taking a look at the three vital ingredients required to make your diesel or petrol 4x4 live a healthy life, and what kind of preventative measures you can take to ensure it stays firing on all cylinders.


WHEN IT comes to foreign bodies killing your 4x4, dirty fuel is right up there, especially when travelling to the more remote corners of Australia.

While all internal combustion engines are susceptible to damage, none of them are quite so much as the common-rail diesel engine. Older mechanical injection systems like Nissanís trusty TD42 typically ran around 1500psi of pressure in their injectors. Current generation common-rail diesels bump that figure up 2300 per cent to a whopping 36,000psi, which is enough to cut through a grown manís hands. The result is that every component in the fuel system is running that fine a tolerance, and that fast, that even the most minute spec of dirt can slice the fuel pump and injectors to shreds. The resulting poor spray patterns can cause your engine to burn excess fuel, billow soot and, if the injector dribbles fuel, create hotspots on the piston leading to a hole and the need for an engine rebuild.

While particles in your fuel are a serious issue, the main factor most people will come across is water contamination. There are three different ways this typically occurs, and theyíll need three very different methods to combat them. The first and biggest one to keep an eye out for in a 4x4 are river crossings. Sinking your 4x4 to the belly pan in deep water is an expensive way to test your fuel systemís weather sealing. Split low-pressure lines, breathers or improperly sealing fuel caps will all allow water to enter the fuel system. A new cap and a few metres of hose in an older rig are enough to prevent these issues.

Because of science, diesel fuel tanks are far more likely than their petrol counterparts to suffer from excessive condensation build-up, especially in colder areas. Over time this condensation can build up, leaving a layer of water in the bottom of the tank waiting patiently to be sucked into your fuel pick-up. Luckily itís a relatively small volume of water, and keeping your tanks as full as possible will reduce the air volume and potential condensation build-up.


Water is heavier than diesel, so squirting contaminated fuel into a clear container should quickly reveal hidden contaminants.


In dust, every inch of your 4x4 is put to the test, and something as simple as a poorly fitting fuel cap can result in contamination.


If youíve picked up contaminated fuel from an outback service station, youíll need to drain the system and replace filters.

Finally, the horror stories we all hear: dirty fuel from outback service stations. Just like your 4x4ís fuel tank, low turnover (and low tank quality) can lead to water contamination sitting in the bottom of fuel tanks. Itís also present in urban servos, though less likely. Itís typically a major issue after a fresh batch of fuel has been poured in and the water is stirred up with the fuel.

If youíre suspect of the fuel youíre getting, squirt a little in a dry water bottle before filling your tanks. A quick swirl will push the heavier water to the bottom clearly showing any contamination.

The last line of defence, and it really should be considered the last line, is a pre-filter and water-separator kit. There are pros and cons for pre- and post-filter setups, which weíll go into on another day, but a water-separator kit is a no-brainer. They typically work as a centrifuge, spinning the fuel and forcing the heavier water to the bottom. Kits will either run a glass bowl requiring inspection or an internal sensor thatíll sound a buzzer, alerting you to the presence of water in your fuel, hopefully in time to shut the engine down and drain the fuel system.


IF FUEL contamination has turned your brain to goo, donít stress, air contamination is a much simpler problem and one pretty easily solved.

Like your fuel system, your engineís internals are machined to fine tolerances for a variety of reasons. The first is to maintain compression. Without that, the pistons cycling wonít be able to properly form compression, so the air and fuel mixture will simply slip past the gaps rather than push the piston down giving you drive.

The second is to keep your engine properly lubricated by cutting a crosshatched pattern into the cylinder walls, giving the engine oil something to stick to.

Introducing airborne contaminants into this mix acts like a sandblaster, eating up and smoothing down anything in its path, smoothing out the cross hatching and removing your engineís ability to properly lubricate itself, resulting in catastrophic internal failure. Issues can also rear their ugly heads in the form of worn valve stem seals and piston rings causing excessive oil consumption, low power output and hard starts.


Air contamination in your engine acts like a sand blaster on internals, so blowing out your filter should be a daily routine in remote country.

Engine ancillaries are in the line of fire, too; dust contamination before the turbo can eat it to pieces, while air-intake sensors can also get confused and cause problems such as the widely reported Mass Air Flow meter problem with some Toyota 1GD-FTV Hiluxes, causing engines to go into limp mode.

Unlike fuel, youíre not likely to pick up bad air at a service station, so solving these issues is more a case of minimising the amount of dirty air going into your air-intake and making sure none makes its way into your engine.

First things first: run a snorkel. Dust is heavy and likes to stick as low to the ground as possible. By raising the airintake up a metre or so above the spinning wheels youíre already doing your engine a favour. Likewise, running a rearwardfacing snorkel, or spinning your snorkel head backwards, can reduce the amount of dust ingress. Snorkel pre-filters can be used to further cut down dust ingress.

From here youíll need to address the air filter. In most cases the OEM air filter element is fine enough to remove any particles in the air. A cleaner air filter isnít always better, though, as a build-up of contaminants on the atmosphere side can help improve filtration levels. Youíll want to pay close attention to the sealing of the air filter, though; any dust on the engine side of the air filter is a sign thereís a problem with the filter itself, or the filter isnít sealing properly. A light smear of grease on the edges can fix this.


When travelling in convoy, space yourself apart from other vehicles in order to minimise the potential for dust ingress.

Finally, and one people often forget, is that after the air filter thereís still a long system of potentially vulnerable pipework to the engine.

Modern sensor-laden engines are less susceptible to undiagnosed intake leaks, but itís still worth checking the intake plumbing. Petrol engines can be checked by starting the engine and then spraying Start Ya Bastard along the length of pipework between the filter housing and engine intake, and listening for any rise in idle speed. Diesel engines will typically need to be checked over by a mechanic to detect any leaks in the intake system.


IF YOU thought contaminant issues were only caused by things you accidentally allow into your 4x4, youíre unfortunately mistaken, and possibly in an expensive way. Just like your engine needs its air and fuel to be in tip-top shape, the oil keeping the whole shebang together is just as susceptible to contaminants.


Regular servicing will keep most internal contaminants to safe levels, although oil sample analysis can help diagnose issues before they cause problems.


Aftermarket filters and breathers can be a cause of contamination so should be checked regularly for a dusttight seal.

In perfect working order your oil should be thick enough to properly lubricate all the moving parts inside your drivetrain, yet thin enough to make its way through the engine from top to bottom, even in the dead of winter. And soapy enough to prevent carbon build-up in the oil galleys, carrying contaminants to the oil filter ready to be physically removed when you next have your vehicle serviced.

Over time diesel soot from engine blowby and metal particles from bearing and ring wear cannot only affect your oil viscosity, reducing cold-start lubrication, but can also increase wear on internal components, drastically reducing your engineís working life. Luckily, regular oil and filter changes are enough to prevent these issues.

When you next drain the oil from your engine, set some aside for an oil analysis. This is one of the most powerful diagnostic tools at your disposal and will help identify any underlying issues such as slow coolant leaks through seal degradation.


AS SOON as you talk popping-the-bonnet, many 4x4 owners fall back into the typical argument of ďthe manufacturer designed it that wayĒÖ and that is true. After all, vehicle manufacturers spend millions on research and development to put these vehicles on the road. The problem is, and itís a doozy, this argument tends to forget about capitalism.

These manufacturers arenít doing the world any greater good by producing the very best 4x4 they can; theyíre doing it to make money. Itís the reason new 4x4s donít roll off the factory floor with lightweight alloy wheels, high-end bypass shock absorbers and 1000Nm V8 diesel engines.

Letís do the maths. Over a 12-month period Ford Australia sells around 40,000 4x4 Rangers. At a typical retail cost of $50,000, that equates to a $2 billion turnover a year in Rangers alone, just in Australia. By not installing a $100 filter that most city-dwellers wonít even need, Ford can save roughly $40 million over the typical 10-year sales life of the model. Kinda makes sense now why they might save money on gear most customers wonít really need.