There are many dangers involved when driving through, or being caught in, flood waters, despite the fact that many vehicles are able to successfully climb out of them. The engine can take on water, which can lead to a ‘hydraulic lock’, where the water locks solid inside the engine. This can cause associated pistons and rods to smash.
There is also the prospect of shorted out electrics, especially on petrol vehicles, and the added and much more concerning risk that a vehicle can easily be carried from shallow, manageable waters into deeper and more dangerous ones with people still inside.
Obviously, if you come across flood waters whilst driving the first thing you’ll want to do is avoid it entirely if possible. If there are more than four inches of moving water or six inches of stationary or standing water, the risks involve with driving through it increase notably.
Selfish though it may seem, it may be better to pull up to the side of the road or waters and see how other motorists fare as they attempt to tackle the waters, and this will also give you a better idea of the water’s depth. Look closely for any dips or changes in height that the water has otherwise disguised, and assess your chances of successfully navigating the waters accordingly.
Even those driving large 4x4s should be wary despite the extra height they enjoy. The water should be entered as slowly as possibly, approximately 1-2mph according to experts at Land Rover, before accelerating to about 3-4mph. This will create a wave in front of the vehicle, meaning the air intake remains clear, due to the creation of a depression in the engine bay. However, this technique isn’t suitable for beam-axled 4x4s and can create further problems.