Show me

Take care when crossing water in that 4WD

We’ve all seen the ads on TV: Mr Rugged Outdoor-type heroically crossing a river in his Mitsuyota V6 Vandal, or whatever it is, water splashing off wheels, smiling kids in the back, admiring wife gazing longingly at his steel-jawed manliness while the 4WD motors onward. Climb every mountain, ford every stream and all that stuff.

For many 4WD owners crossing water is something of an off-road rite of passage. Well it’s one rite of passage that requires a good deal of thought and preparation, because unlike those TV fantasies it’s not just a matter of plunging in and boldly going where no 4WD has gone before. There are many ways to get it wrong and the consequences can be costly and embarrassing at best and fatal at worst. People have died in river crossings gone wrong.

Be prepared

Safe and successful water crossings start well before the water’s edge. The first thing to know is your vehicle’s wading depth. That’s the maximum depth your vehicle can safely cross still water with a flat bottom. That figure can vary quite a bit between 4WDs and it’s determined by things such as the height of the air intake and electronics. Those wading depths are an excellent indication of what you can safely and successfully cross.

Anything deeper than that and it gets potentially hazardous, so I’ll preface what I’m about to say with this stern warning: cars float. Yes, even big, heavy 4WDs become unstable in as little as 45cm of flowing water and can float away completely in less than a metre of water. One cubic metre of water weighs about a tonne and packs a lot of force when it’s moving. You have been warned.

If you still insist on wading in then a well-designed and properly installed snorkel is vital if you’re to avoid wrecking your engine when it sucks in water. It’s also a good idea to extend the air breather tubes on the various sections of your vehicle’s driveline. You don’t want cold water being sucked into them, so extend them into higher parts of the vehicle, tie them with cable ties and make sure they have enough slack to move along with the axles moving. You’ll find commercial breather kits that will do the job well.

A well-designed water blind in the front of your vehicle will stop a lot of water from getting under your bonnet and causing mayhem. Yes, you could make it yourself but a good commercial one is less likely to come off halfway across that river.

Finally it’s let us spray. A good precaution is to spray your electrical components with WD40 before entering the water to help disperse moisture.

Ford every stream

Alright, so you’re all prepared and ready to go. It’s the ford every stream moment. Well before you do that sit down and have a nice cup of tea and a think about it. For starters that will give your engine a chance to cool down, reducing the chance of damage when those hot components hit that cold water.

While you’re there figure out exactly where you’re going to come out on the other side. Half way across is really not the time to think about that.

There’s really only one way to find out how deep and hazardous the water is and that’s to wade in and walk across. This is not a good idea if you’re in Northern Australia where today’s intrepid 4WD adventurer is potentially tomorrow’s crocodile crap. If the water’s flowing so strongly that you’re having trouble standing then just forget it unless it’s also very shallow.

In fact if there’s one golden rule of water crossings it’s never cross flood water. Don’t even think about it! It’s full of hidden dangers, that water is bound to be flowing very fast and it’s highly likely you’re going to be washed downstream with potentially lethal consequences.

Alright, so with that in mind it’s time to go. Select 2nd gear low range or drive and low range if you’re in an automatic (select 2nd gear if that’s possible). If you’ve got air suspension raise it. Drive at a steady smooth momentum at a fast walking pace and don’t use the clutch. Press the accelerator if needed to overcome the resistance of the water. A bit of a bow wave in front prevents water from going in your engine bay. Have your recovery equipment, like snatch straps and winch extensions, ready in case it all goes pear-shaped mid-stream.

Exit checks

So you’ve reached the other side. You hero, you! But before driving off with an air of smug superiority, park up near your exit point for a few minutes and allow the water to drain away. That will help minimise erosion on the river bank while clearing water from your undercarriage. Next check for any debris that might be lurking beneath the vehicle or in the engine bay before heading off again into the great beyond.

Leave a comment

Your email is required, but will not be published.

Submit