Upon approaching water crossings with your 4x4, a few things need to be considered before barging in.
Ensure that it is safe to exit your vehicle. (Dangerous animals)
Assess the terrain and see if other vehicles have crossed recently.
Observe the water for flow rate and possible hazards.
Walk through the water if necessary by walking along the one side wheel path and returning on the other wheel path whilst also measuring the height of the water at the deepest point. A walking stick is handy for this.
Stand on one leg in the water to determine if the flow is too strong. If you cannot stand on one leg, then the flow is possibly too strong, and might wash your vehicle downstream.
If you are confident that you can cross, prepare your vehicle for the crossing.
If in convoy, connect your pull strap before you enter the water.
You would have ascertained the vehicles wading depth.
Tyres should be deflated for maximum traction.
Wind down windows and open sunroof, for quick escape if necessary.
Spray water repellent oil on critical electrical components in engine compartment. (latex gloves work well on old type distributors)
Select a suitable low range gear. (Normally 2nd) Don’t change gears in the water.
Remove seat belts and enter slowly following the predetermined line to your departure point.
Speed up till a bow wave is formed in front of the vehicle. The bow wave will cause a lower water level next to the vehicle and create a cavity in the engine compartment.
Be sure to exit well clear of the departure point to allow the vehicles behind you a safe exit. Vehicles dump lots of water on the exit bank, so the exit bank will become slippery and more difficult for the vehicles at the back of the convoy, if possible, exit slightly to side of the previous vehicle.
If your engine stops while in the water, assume that water has entered the cylinders. Remove keys and hand them to your co-driver. DO NOT try to start the engine, because if hydraulic lock has occurred, the engine will be severely damaged by the starter motor. Get pulled out of the water and do the following.
If the vehicle has a petrol engine, remove spark plugs and try to turn the engine by placing a spanner on the crank pulley and turn by hand. If the engine turns, use starter motor to turn engine and eject the water from the cylinders. Spray water repellent oil into cylinders and replace spark plugs. Dry out air filter in the sun while you set up camp.
In case of a diesel engine, you would remove the glow plugs. (Worst case, the injectors) This is a more complicated process than spark plug removal, but with some tools, is easily doable by the average traveller.
When you return from your trip, do an oil change on all the diffs, gearbox, transfer case and engine, as water is sometimes ingested through the breathers. Service the breathers and place as high as possible or fit extended pipes.