Water Crossings – Serious Business

If you took any notice of the TV ads selling four-wheel-drives, you might think you could plunge into water without concern. Don’t believe it. 4WDs aren’t boats, and water can get into vital components very easily. Damage can range from water-contaminated wheel bearings to a complete write-off.

Driving a 4WD through water that is deeper than its hubs should be done with extreme caution. Above that depth – about 300mm – you start to dip oil and grease-filled components into the water. Of course, if you drive at high speed through shallow water like the lunatics on TV, you’ll spray water up inside the engine bay and into body and chassis cavities, where it can cause corrosion.

Another more serious consequence of high-speed crossings is water spraying into the engine air inlet where it can, at best, put the fire out and, at worst, cause the engine to “hydraulic” (destroy itself as the pistons slam into water that was sucked
into the cylinders).

Forget all the advertising when you have to cross a stretch of water. Stop the vehicle, get out and have a look. If you can’t see the depth of the water and the nature of the bottom from the shore, you’ll have to walk through the water. Walk in one direction, where you plan to run the left-side wheels, and return by walking where the right-side wheels will run.

Rapidly flowing water is dangerous if it is more than knee-deep. Knee-deep water over a firm bottom shouldn’t cause problems for most “real” 4WDs – vehicles with low-range gearing and good ground clearance. Select low first or second and drive at low, steady speed, making a small “bow wave” in front of the car.

Thigh-deep water is a different matter. Many engine air inlets will take a drink in water of this depth, and engine damage can result. A snorkel with water-tight clamps will keep engine air dry, but you may still need to tie a plastic sheet in front of the radiator.

It is vital to keep the engine running during a water crossing. If the vehicle keeps moving in thigh-deep water, a radiator “blind” should keep the engine bay relatively dry. But if the engine stalls, water will rise in the engine bay and inside the vehicle. Drowned computers, sensors, fuse blocks and connectors are no fun in the bush. Axles, diffs and the transmission will be underwater, and these casings can also draw in water, even with extended breathers fitted.

No production 4WD and only a few military vehicles can handle water a metre deep. Beach driving also has a special hazard – the tide. It is unwise to drive on a beach on a rising ride because if you get stuck you mightn’t have time to get the vehicle out before the tide drowns it.

About Olmate 4x4

No one knows 4WD’s better than Troy Whitelam of Olmate 4×4. Troy doesn’t just sell 4X4 gear, he installs it and he uses it. Troy’s 4×4 training courses have a huge following in the Central Coast of NSW. He’s practical knowledge is based on thousands of hours researching and testing for himself in real off road and recovery conditions. Troy doesn’t recommend the gear he sells – he sells the gear he recommends.

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