Water Crossing Techniques

There are 3 main things that stop an engine working: no spark, no air and no fuel.

Water crossing can affect the first 2: water shorting out the ignition system or water in the air cleaner.

Ignition Systems

In older vehicles there is a coil, a distributor and spark plugs. Water can enter the distributor and cause shorts inside the distributor cap and under the caps of spark plugs. Water can also short out the spark plug leads if there are cracks in the insulation.

Newer vehicles don’t have a distributor, but still have spark plugs and leads. In some cases the spark plugs are inside the heads and are protected from water. But if the leads are perished, water can still short them out. In newer vehicles there are also computers controlling the motor, gearbox, etc, which can also be affected by water.

In older vehicles silastic was used to seal the distributor cap and spark plugs. The same can be done on newer vehicles.

Air Cleaners

Water can enter the air cleaner and stop the air flow or be sucked in and stop the engine.

Older vehicles' air intakes were usually in the centre of the engine bay above the carburettor. It was easy to fit a piece of pipe that could be run to the back of the engine bay where there was less chance to suck in water. Newer vehicles have air intakes either behind the headlight or between the top of the grille and the bonnet. These air intakes are designed to ram air into the air cleaner, the trouble is that they also ram water into the air filter. The better designed air inlet systems have water traps, which remove the water before it can enter the air filter. The safest system is to have a snorkel fitted.

Before Crossing

Do you really need to drive through the water? Is there another way or a shallower crossing? Anything above doorsill height deserves caution. Vehicles can float and water can enter the cabin.

Deep water crossings should never be attempted alone, except in an emergency.

Before you enter any water, you must check the path you plan to take to find any big rocks or deep holes hidden under the water and to check the firmness of the bottom and the current flow.

A radiator blind prevents water being forced through the front grille, then through the radiator core resulting in flooding of the engine bay. Removing or loosening the fan belt will prevent the fan blade from being driven into the radiator and splashing water all over the engine. If you have electric fans, turn them off. Also turn off the air conditioner. If the engine and transmission are very hot consider letting them cool down before entering the water; especially engines fitted with turbo chargers.

The Crossing

Enter the water slowly, then increase your speed to build a bow wave and maintain the momentum, which effectively lowers the water level around the engine and behind the vehicle. Driving too fast could cause water to surge over the bonnet and flood the engine bay. Don’t change gear while in the water. Travel diagonally to the current flow. If you start floating, open a door and fill the vehicle with water.

After Crossing

On leaving the water, always drive a short distance with the foot brake lightly depressed to dry out the brake linings.

Upon returning home after water crossings, check the diff and gearbox oils for water contamination, especially after long or deep water immersions.

Ron Penfold SC002