The Unsealed 4×4 guide to water crossings

By Unsealed 4X4 12 Min Read

Motor vehicles are essentially just bits of tin filled with oil, fuel and air. Not even the radiator is filled with the simple old H2O anymore. So, when we decide to drive through water, and we don’t want a drop of it inside our delicate cabin or moving parts, we must be barmy!


But as treacherous as water crossings can be, they really do often make the adventure. And if we didn’t have to cross creeks and rivers, well, the adventure wouldn’t be half as much fun.

Getting set to get wet

Simply driving up to an unknown river, sticking her in low-low and heading in is a recipe for disaster. It’s tempting, and believe me, I’ve done it plenty of times. But a few times I’ve lived to regret it. Put simply, there is no way of knowing what a water crossing is like unless you walk it on foot. This is one of the few times when you realise that not everything about four-wheel driving is fun. Wading across an icy high-country stream in your undies is something akin to water torture. But it is necessary.

Some of the deepest and most treacherous crossings also boast some of the clearest water. Clear water can act like a magnifying glass. Making the bottom of the creek look a lot closer than it actually is. And a really deep crossing can look like it might only come up to your knee. Coffs Harbour’s crystal-clear mountain streams are one place that I’ve got it badly wrong by underestimating the depth.


How things can go wrong in water

Years ago I took a brand new press vehicle – a $116K Range Rover nonetheless – through what I thought was a wheel-deep crossing. It wasn’t. I drove through (or attempted to) before the Rangie engine sucked in a bellyful of water, causing what’s known as hydraulic lock. In that ’96-model Range Rover, the engine computer was under the driver’s seat, so the alarm went off, the electric windows didn’t work, and the lights promptly turned into fish tanks. It took more than $12,000 to get that Rover back on the road. Oops. So use me as an example, and don’t cross unless you’ve walked it first, no matter how clear and shallow it might look.

Walking the crossing also shouldn’t be a straight across and back affair. On your walk across, try and zigzag your way over – this way you’ve got a better chance of picking up on unexpected holes and depressions on the creek floor. Feel the bottom of the creek and try to assess what sort of traction you’ll get. Also, feel the flow of the river. If the water flows too fast to walk, then it’s almost certainly too dangerous to cross with a vehicle. If there is a strong current but you still think it’s drivable, start upstream of your exit, taking into account that the current may push you downstream while crossing.

Crocs safety and water crossings

Of course, there’s always an exception to the rule. Saltwater crocodile-infested water crossings (they also live in fresh water) can be extremely tough to walk. Given the traffic on the major 4X4 tracks, I doubt too many crocs would find them a peaceful place to live, but you can never be too sure.

The way I see it, you’ve got three options here. You can either walk the crossing using a lookout or two to make sure there are no crocs in sight. Or, you can not walk the crossing at all and chance it. Or you can be really smart, have a cup of tea, and wait for some other poor bugger to come along and either walk it or drive it – either way, you’ll soon see how deep it is!


The next step is to make sure you have all of your recovery gear at the ready and in working order. Water enters a non-moving four-wheel drive in seconds, so any time spent trying to locate straps and shackles could spell disaster for your 4X4. For particularly tricky crossings, it can even be a good idea to hook up a strap on your front and rear, so if you do get caught, it can be a 10-second recovery.

For any water crossing deeper than hub height, it’s always a good idea to fit a water blind. This can be as simple as a blue tarpaulin strapped to the front of your 4X4, or as fancy as an MSA 4X4 Accessories water bra. The latter is a great design with elasticised edges and two straps that wrap around your rear-vision mirrors to keep the blind in place. It also has a bag off the front to provide storage for shackles and straps.

Stop and wait

Another good precaution to take on any water crossing is to stop beforehand and let your vehicle cool down a little. This is for a few reasons. Firstly, hot engine parts like manifolds and turbos don’t take well to being cooled instantly in cold water. They can crack, causing you expensive damage. And secondly, differentials also get hot, and when they cool down quickly, if their breathers are submerged, they’ll suck in a gulp of water. Hence, you’ll end up with a milky mix of oil and water inside your diff, leading to rust. This, however, can be stopped by extending your differential breather hose. It’s a simple mod that most could do in their driveway over a couple of hours.

Other engine components may also be susceptible to water damage, like distributors on older vehicles. If you think that’s the case with your fourbie, give those parts a spray of water dispersant like Lanotec.

And lastly, check the position of your air intake. If in doubt, ask your mechanic. Air intakes are usually up the front of the engine bay, or tucked into the inner guard. This is the part that your engine breathes from, and it acts like a vacuum cleaner trying to suck in air. But if that air turns to water, it will kill your engine.

Fit a snorkel

You might be lucky enough to have a snorkel fitted, which increases the height of your air intake dramatically. Just check, though, that your snorkel isn’t classed as a ‘dust’ snorkel, as are fitted standard to some vehicles. While I’ve never had one fail, the original-equipment manufacturer claims these are not meant for deep water crossings, only dust (presumably to avoid warranty claims).

Speaking of warranty, if you’re driving a 4X4 that is still under new vehicle warranty, it might be wise to check your manufacturer’s handbook to see the permitted wading depth of your vehicle. Go too deep, and when your engine goes pop that $15,000 bill might need to come off your or your insurance company’s bank balance.

Dive in the water

Right, so now that you’re sure your vehicle is ready to make it across, you need to select the correct gear. With an auto, it’s easy, just select ‘Drive’. A manual vehicle is slightly more challenging, keeping in mind that you never want to stop or slow (or change gears) on your way across the river. Pick a gear that gives you plenty of torque, plus enough speed to create a bow wave. One of the most popular gears is second low range, but as always that depends on your own vehicle’s engine and gearing. Select what you feel is the best.

For the drive across, you want to create a ‘bow wave’ out front. A bow wave means you’re travelling fast enough to push a small wall of water in front of the vehicle, creating the wave effect. This creates a big air pocket under your bonnet, in theory keeping your engine bay relatively dry. Often enough, though, four-wheel drivers can get a little excited, and push a whole lot more than a bow wave. Driving too fast can push water up onto your windscreen (meaning you’re temporarily blinded), and it can also allow water to wash down between the windscreen and the bonnet, in some cases leading to water damage.

Another common occurrence for drivers that ‘punch’ the water crossing too hard is that the force of the water punches the radiator fan into the radiator, causing expensive damage. On one recent visit to Cape York, the notorious Nolan Brook claimed more than 60 vehicles in this way. Of course, none of them wore a protective water blind. At least one vehicle’s busted radiator went unnoticed, overheating the engine further up the track.

In conclusion

So, keep a steady pace across the river, trying not to stop at any time, and maintaining that bow wave. Once you reach the other side, pause and let the water drain away before driving off. Also, remember that water in your brakes can inhibit their performance (particularly drum brakes), so you might like to pump your pedal a few times on flat or uphill stretches to dry them out, before you really need them.

Incidentally, when it comes to flood waters, don’t ever attempt to cross them. It seems that the bigger the flood waters, the more people think they can drive across the raging torrent. Do yourself and your family a favour and give those ones a miss.

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