How To Water Crossings, Part 1 – Vehicle Preparation.
Most smart four-wheel drivers will only attempt water crossings if they have to because, if it all goes wrong, it’ll likely be a very expensive lesson learnt. But sometimes you’ve just got to get to the other side, so check out Unsealed 4X4’s How To Water Crossings Part 1, which covers everything you need to do to make sure your vehicle is up to the task before dipping a toe into the water.
The first thing you’ll want to do is make sure your engine doesn’t ingest any water, and the best way to do this is to fit a good-quality snorkel, not some cheapo thing you found on eBay. If your engine does take a big gulp of water, there can be catastrophic consequences. If you’re lucky the engine will just stall, leaving you stranded in the water; if you’re not so lucky the engine can suffer from hydraulic lock, which is what happens when the pistons moving up and down in the cylinders try to compress non-compressible water, leaving you both stranded in the water and with a very expensive repair bill.
If your vehicle doesn’t have a snorkel fitted, you’ll want to check under the bonnet to see where the air intake is, and have a look in the owner’s manual to see what the maximum wading depth is. Try not to exceed it.
Water crossing cover
A water crossing cover, sometimes referred to as a bra, is designed to keep water out of your engine bay as you drive through a body of water. It is only effective with forward momentum; if you stop in the middle of the water it will be of no benefit.
For vehicles not equipped with a snorkel a water crossing cover is vitally important; and for vehicles with a snorkel fitted it’s still extremely beneficial. There are many purpose designed water crossing covers on the market that are easy to fit to vehicles, or you could use a tarpaulin and attach it to your vehicle with rope.
As well as lowering the chance of the engine ingesting water, a water crossing cover can help keep water away from electrical components such as the ECU, fuse boxes and alternator etc. as it will divert water around the front of the vehicle instead of letting it flood straight into the engine bay.
A water crossing cover also keeps water away from the radiator’s cooling fan. Modern vehicle cooling fans are usually made from a flexible material such as nylon, and when water hits a spinning fan it can bend the blades enough that they will make contact with, and even cause irreparable damage to, the radiator.
It’s also a good idea to spray a water dispersant such as WD-40 around vital electrical components before driving through water.
A set of good quality diff, gearbox and transfer case breathers will minimise the chance of water getting into these mechanical components.
Pressure builds up inside diffs, gearboxes and transfer cases as the heat up while you’re driving, so these components are equipped with a one-way valve (breather) that allows this pressure to be alleviated. When the diffs, gearbox and transfer case are plunged into icy cold water, they cool rapidly and the pressure inside is reduced, creating a vacuum, so they will want to suck in water. The breather is designed to prevent this, but is not always effective, and even if it is, the vacuum inside the diff can result in water being sucked in through oil seals.
Good quality aftermarket breather kits replace the OE one-way valves with diff-breather extension tubes, the open ends of which are affixed high up in the vehicle’s engine bay where they won’t be submerged in a water crossing. Unlike OE one-way valves, they will also be fitted with a special filter that lets air in and out but prevents water ingress.
If you drive an old Defender like me, any water crossing will see the wet stuff sloshing around at your feet, so make sure valuables like Canon G12 cameras (don’t ask) are not left on the floor. If you drive any other kind of 4×4, water should be kept out by door seals and the like (so long as you don’t stop… or go too deep), so make sure they’re in good condition and not loose.
If you drive a ute, remember there usually isn’t a seal around the tailgate, so if the water is deep the tub can fill up.
* Keep an eye out for ‘How To Water Crossings Part 2 – Checking the Water’. In this instalment we’ll look at how to check the water crossing itself to ensure you get safely to the other side.