Most SUV or 4×4 owners’ skill levels are compromised by their lack of actual 4×4 experiences and this is reflected in the ever-present level of fear when going off-road. Fear of damaging the vehicle, fear of getting stuck and fear of getting lost. In our fifth advanced driving article on Fieldcraft Mobility, we take a look at deep water crossing which is potentially one of the most rewarding off-road driving techniques to master but can often end up costing the owner dearly, if done incorrectly. Water is physically incompressible in an engine cylinder, which simply means that should any enter your vehicle’s engine, the resultant damage could be spectacularly expensive. Normally I recommend the fitment of a proper snorkel to the vehicle’s air-intake and extending your differential breathers higher up the chassis of your vehicle by means of inexpensive plastic tubing, before venturing through deeper water obstacles.
It is imperative to check the depth of a water obstacle properly, before attempting to cross it with your 4×4. The rule of thumb is: If you cannot walk it, you cannot wade it.
This rule also applies to fast-flowing rivers, which are impossible to safely walk across. Always do a check for hidden rocks and potholes and remember that previous vehicles that started wheel spinning when they encountered a submerged or hidden rock sometimes create potholes. Place stick markers where you find these in order to avoid them during the actual crossing.
It is vital to bear in mind that petrol engines that have ingested water will stall in most cases, before damage occurs. In cases such as this, do not attempt to restart the vehicle as the engine’s connecting rod (conrod), pistons or valves will bend and/or break. Rather have the vehicle recovered with outside assistance. Should the depth of the water be more than the bumper height of your vehicle, additional preparations may be necessary, before entering the water, such as fitting wading plugs to your clutch housing and/or differential axles.
In addition to this, you can also remove or slacken your fan belt to prevent water being splashed around the engine compartment. If your vehicle is equipped with a viscous coupling type of fan, it will slow down by itself when encountering water.
Ensure recovery equipment in the vehicle is accessible at all times! If you vehicle is not diesel powered, spray the ignition system with a good water repellent, such as WD40 or Q20 beforehand. Place a tarp across the front of the engine to minimize water entering the engine bay. This also prevents water being splashed over the ignition system and the fan “propelling” its way through the radiator.
Driving at the correct (moderate) speed when water wading is imperative. Remember to wind down your window and take off your seat belt. Select low range, second gear and keep the revs around 2 000 r/min. As you enter the water, accelerate gently and do not create a splash that can wet electrical systems. Drive at a steady speed, as this will create a small bow wave in front of the vehicle.
Should the vehicle start wheel spinning, gently ease off the accelerator to regain grip. Do not change gear or momentum will be lost and water may enter the clutch housing and cause clutch slip. Once you have successfully crossed to the other side, some additional maintenance is essential for your 4×4 vehicle. Allow the vehicle to cool down and gently loosen the drain bolt of your differentials.
The last two pointers should be an absolute must for drivers who plan to do regular water crossings. Remember, when a hot axle hits the water, the cold water rapidly cools it and as a resultant the air pressure inside the axle and differential housing lowers. This sudden reduction in air pressure can actually suck water in via the axle seals if the differential breathers do not equalise the pressure fast enough. This in itself is another reason to allow the vehicle to cool down first before attempting a water crossing.
Remember, water is heavier than oil, and thus will collect at the lowest point of the differential. Drain off about 20ml and check to see if the differential oil appears milky in colour. This would indicate water contamination, which means that the differential needs to be flushed and the oil needs to be replaced immediately! You may also want to check the gearbox, transfer case and engine oil for good measure.
If your 4×4 is equipped with an electric winch, it is advisable to strip it and grease it accordingly. Your winch may not be utilised for an extended period and you may find that it has seized up when called upon one day!
Finally, bear in mind that your brakes (especially drum brakes) may be wet and thus useless until they have dried out. This is especially important when a steep ascent or descent is planned immediately after the water crossing. In our next Fieldcraft Mobility advanced driving article, we will cover snatch strap recovery techniques. In the mean time, safe 4×4’ing and remember that the environment comes first. So tread lightly!
About the author: Johan de Villiers
After originally trained by the 1994 West German Camel Trophy team, Johan has extensively traversed a number of Central and East African countries, including Tanzania, Zambia, Madagascar, Malawi, Mozambique, Botswana, Namibia, Swaziland, Zimbabwe, Uganda, Rwanda, Kenya and Zanzibar. On his return to corporate life, Johan has continued to enjoy the outdoor lifestyle and has since led numerous expeditions through Southern Africa. In addition to being a qualified Land Rover recovery expert, Johan is a qualified helicopter pilot, high altitude mountaineer and a regular contributor to various 4×4 publications. His personal vehicle is a highly modified Land Rover Defender 110 TD5.