Driving into water without checking if it is safe to cross can get you into deep water AND deep trouble. It can leave you stranded and may even write off your vehicle’s engine. It’s prudent to avoid exposing your vehicle to all water as far as possible, but what do you do if you have to cross a river and then get stranded in the middle?
When you get to a water crossing, first look for any fresh tyre tracks exiting the crossing point as these will give you some indication that someone else made it across. Check them to try to assess if they belong to a vehicle similar to yours and not a tractor or Unimog!
If there are none then remember the golden rule about water crossings: if you can’t walk it, don’t drive it. So you should walk one way where you think the left tyre track will be and back in the right tyre track whilst you check for depth, rocks and holes.
This procedure obviously poses a problem when you are in a wilderness area where crocodiles, hippos and predators prevail. At the very least before you get out of your vehicle look around carefully for dangerous land mammals. Then if you have decided to wade, stamp on the ground and wait for a few minutes while you survey the area for dangerous animals in the water. Watch for ‘logs’ that move and heads that slowly rise out of the water. Remember that wading an African river is extremely risky.
If you have to cross, but don’t wish to wade and are in doubt of the safety of the water level, then engage low range and diff lock and drive your vehicle very slowly into the water. Two passengers each with a pole marked to the top of the wheel height, sitting on the bonnet above each wheel, will be able to sound the depth in front of the front wheels and warn the driver of an increase in depth before the front wheels plunge in. However, like wading, that is obviously also a dangerous practice but may prevent you from driving into a hole and flooding the engine.
Otherwise, watch the water level through open windows and reverse when the water level gets to the top of your front wheel arches. If in doubt, set up camp on the river bank, hope for someone else to come along that can pull you out if you do get stuck, or wait for the river to drop. Otherwise find an alternative route. Even if it costs you a few hours or a whole day, it will be much better than trying to salvage a drowned vehicle.
When crossing, keep your speed low enough to prevent water from coming over the bonnet but high enough so that it is discouraged from flooding the engine compartment. Going that fast, however, can mean that the vehicle will go too deep into a sudden drop before you can react. Sticking a large sheet of plastic over the front of the vehicle might minimise water entering the engine compartment.
What to do if your vehicle stalled in the water
If your vehicle stalled in deep water, do NOT restart it, even if you have a snorkel fitted, as any water in the pistons will mean the con rods could be bent. Tow or winch the vehicle out of the water as soon as possible. Once on dry ground, the very first thing you have to do is to ensure that there is no water in the engine by removing the air filter and checking to see if it is wet.
If it is, you have to remove the glow plugs or spark plugs. Then crank the engine to squirt out any water in the cylinders. Reassemble the plugs and try to start the engine with the air filter off, as a wet filter won’t allow air through. You will have to dry the filter before reinstalling it, or install a new one.
If the vehicle won’t start after flooding, then check the fuses. If that doesn’t solve the problem then it’s likely that the electrics are wet and you will either need to give them a chance to dry out or will need a tow to the nearest mechanical workshop. If you successfully started your vehicle, you should also check the drive train oils for water contamination the next morning.
Immersing a hot transmission without raised transmission breathers fitted will most likely cause water to be sucked in as the internal air and fluids cool. If you have to cross water and don’t have breathers fitted, then wait for everything to cool down completely before you make the attempt. Once you are through you should let any possible water settle and then check.
To do this get a clear plastic bottle and cut the bottom third off to catch the fluid. Then crack open the drain plug and allow a little fluid to flow into the bottle. You will be able to see if water is present as any oil will float on top. If there is water present and if you have enough oil to replace all of it, then before draining any oil, first make sure that the filler plug can be undone to permit you to re-fill the system. The drain plug is underneath the transmission box and the filler plug is on the side of the rear. When you refill, make sure you use the correct grade of oil for each transmission box.
Depending on what you have done and how confident you are about the work, you should maybe get your vehicle to a workshop as soon as possible for a complete check-up, oil and hydraulic fluid changes and an all round flush and clean of fuel and hydraulic lines.