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DESTINATIONS - OUTDOORS HEALTH & SAFETY

PREVENTING AND DEALING WITH 4WD FIRES
A fire is your worst bush-travel nightmare.

 

It seems that there’s a 4WD incident involving fire every day of the week and most of these incidents are preventable.

 

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Directly or indirectly, we’re all paying for the damage caused by 4WD fires, in higher insurance premiums, but much more difficult to evaluate is the cost to the health system of trauma experienced by drivers, their families, other road users and first responders.

Insurance company reports suggest that more than half of 4WD fires are caused by electrical failure and many of those are the result of non-factory wiring work.

 

 

Causes of 4WD fires

 

Arcs in battery cables cause sparks, mainly due to poor electrical installation and poor design practices with alternator cables or positive feed wires into the cabin. Any wiring passing through sheet metal needs to be well protected against chafing and the circuit needs fuse protection. Heavily loaded circuits overheat terminals, causing insulation to burn. Other heat creators are aftermarket fuse holders and minor electrical components. 

Fuel line rubs or failures, or the location of lubrication oil lines too close to the exhaust system result in leaks or sprays of fuel onto the exhaust. Engine-metal operating temperatures aren’t high enough to ignite hydrocarbon liquids, but they are easily ignited by exhaust pipe or turbocharger temperatures.

Turbocharger failures cause excessive temperatures in the air intake. Typically, the turbo centre bearing fails, causing a lubricating oil fire to start and spread towards the boost side, where the fire burns through the boost-side tubes or elbows.

Flammable material, often dry grass and other vegetation, collects beside the turbocharger or the exhaust system. Modern exhaust systems with DOCs and DPFs get very hot.

Tyres catch fire because they are flat or poorly inflated, or they are rubbing on hard mudguard surfaces. Tyres can catch fire after a vehicle stops.

Vehicle-behaviour issues leading up to a fire-causing failure may also occur. For example, a fuel leak can result in rough running and under-fueling the engine, because fuel is escaping elsewhere. Electrical fires are often considered silent, because they don’t create any noise before the fire has started, but a clue could be sudden electrical disturbance noise in the radio or CB.

 

Causes of trailer fires

 

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Trailing equipment causes fewer electrical-fire incidents, mainly because of trailers’ much lower-powered electrical circuits. Trailer fires are caused mainly by wheel-related issues.

Wheel bearing failure results in bearing grease catching fire. Wheel bearing failure also occurs on 4WDs, but less commonly. 

‘Dragging’ brakes are often caused by over-adjustment or damage to the electric-brake system. If there’s a short-circuit in the brake power supply, the shoes or pads can ‘drag’. If a brake friction surface becomes red hot, a fire at the tyre rim can result.

Tyres also catch fire because they are under-inflated or rubbing on hard mudguard surfaces.

Electrical system failures are another cause of trailer fires, particularly where DIY trailer wiring has been done without sufficient knowledge or care.

The other bogey with camper trailers is the LPG system and we’ve covered that separately. Obviously, there should be no electrical wiring passing through the LPG bottle storage compartment.

 

 

‘In case of fire’

 

Assess the situation, making sure you, the vehicle passengers and others around you are safe;

Shut down the vehicle and disconnect the batteries, if possible;

If practical and safe to do so, attempt to fight the fire. (If using a fire extinguisher, it should be used with controlled release, with short movements from the bottom of the fire to the top.)

If practical and safe to do so, uncouple the 4WD, to separate it from the trailer;

Call 000 if in phone range for fire brigade or SES assistance.

 

 

Post-fire report

 

Don’t rely only on your memory of events, because an insurance investigation can take several months to conduct. A driver may not be contacted for a long period of time and investigators rarely inspect the burnt vehicle at the scene. Therefore, you should record all observations. 

As most phones are equipped with cameras, photos should be taken as soon as practical, after all fire fighting efforts have finished and authorities have been notified.

A driver should record observations that include any abnormal smells, noises, vibrations or visual observations prior to and during the fire. Each observation should be recorded against an approximate time of day or night, so that a chronological order of events can be established.

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