If you are an enthusiastic 4-wheeler, crossing water - in the form of creeks, rivers or coastal areas - is probably going to be a regular occurrence. Even in some deserts, a flash flood can transform the scenery into runny stuff quicker than you can pack up your tent.
To cross, or not to cross; that is the question. Water can easily damage a 4WD if you attempt the impossible, or don’t take proper precautions. Salt water multiplies that risk a hundred-fold. Boats float on water. 4WDs drive in water. There’s a huge difference.
Unless you are crossing water that you know well (preferably, on a daily basis), always get out and check the depth, speed of the flow, and whether the bottom is firm and free of obstacles. This means you might have to get your tootsies wet. But that will be better, and a lot less expensive, than finding out by driving the vehicle in and (a) getting stuck (b) drowning the engine (c) filling the vehicle and/or its electronics with water, (d) getting washed downstream - or all of these disasters, combined.
If you are an adult and you cannot walk to the other side; forget it. If the flow is such that you can hardly stand upright, the force on a slab-sided 4WD could be enough to wash you and your pride-n-joy away. If you live in Northern Australia, don’t even think of attempting an unknown water crossing. Many of the creeks, rivers and shoreline areas there are home for man(woman)-eating saltwater crocodiles, and they won’t even wait for you to say, ”Would you like fries with that?”
If the water is ‘drivable’, these are the minimum precautions you should take:
1) In a 4WD with a part-time system, engage 4WD and low range. In a 4WD with a full-time system, engage low range and the centre diff lock. If you have manually-lockable diffs, lock these as well, but be aware that this could make the steering less effective. Some of the latest 4WDs, such as the WK Grand Cherokee, are available with electronic, automatically-locking front, rear and centre diffs. Too easy!
2) In an automatic, select Drive. In a manual, second gear is usually ideal.
3) If the bottom is rocky, you will need to drive slowly to avoid impact damage. If it is muddy or sandy you will probably need to have some momentum to avoid bogging down.
4) If the water is at bumper height, it is a good idea to try and drive at a speed that will create a bow wave in front of the vehicle. This will cause the water to bank up behind the wave and (hopefully) not right up against the radiator.
5) Deep water can get you into deep trouble. You will need to fasten some sort of a shroud over the grille to try and prevent the fan blades curving forward and damaging the radiator. In the ‘old days’ you could stop the rotation of the fan blades just by removing the fan belt. Sadly, removal of the belt on modern 4WDs often requires the facilities of a workshop. The shroud will also help prevent water being sucked into the air intake. When the engine’s pistons try to compress ‘non-compressable’ water, all sorts of nasty (and very expensive!) things happen. If a snorkel is available for your make and model, get one. They are a wise investment.
6) Water can also get sucked into the differentials if the breather hoses are not mounted high enough. Check this before you start your 4WD adventuring. The modifications can usually be made for a tiny fraction of the price of a new differential. As a short term measure you could plug, or seal off, the breathers. But make sure you open them up again once you are back on dry land.
7) When you exit the water crossing, keep in mind that the vehicle’s brakes will not be very effective until they dry out. Drum brakes may not dry out for many miles, so drive cautiously. Light pressure on the brake pedal can help to speed up the drying process.
A well set-up 4WD will cope with most water crossings a sane, and reasonably intelligent, person would want to attempt. Equipment, preparation, know-how, and plenty of common-sense are the basic essentials.
By Sam Cook
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