How to handle water crossings

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.

Walk through a water crossing before you drive through.
Walk through a water crossing before you drive through to check the depth of the water as well as for holes and rocks.

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.

The water should not be deeper than your front wheel arches.
The water should not be deeper than your front wheel arches. (Photo: Peter Levey)

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.

6 thoughts on “How to handle water crossings”

  1. Either do not cross deep water, or if you absolutely must cross and there is the risk of crocs & hippos, use the SWIF method.
    (Send Wife In First.)

  2. Good tips. Thanks.

    I will keep that front wheel arch water level in mind. As well as the sheet of plastic over the radiator. As well as cooling the gearbox first before going for it. As well as ….(;-)
    About those gearbox breathers. They will no doubt submerge. Will not inevitably water penetrate the gearbox at all circumstances? What would keep the water out, even when cooled down first?

    How about diesels? No sparkplugs to take out. Glowplugs? How do they look like, and what is generally their location ?

    Concerning oil: you write: …the filler plug is on the side of the rear.
    The rear of what?
    As far as I know there is always a oil filler cap somewhere in the engine compartment.


    1. Frank, re breathers, some vehicles have these fitted and they extend to a point somewhere high in the engine compartment. For instance the Toyota Hilux has them for the gearbox and transmission box but not the rear differential. Pete fitted a pipe to the rear dif breather. He led this pipe up to a height above the rear wheel arch and stuffed some loose cotton wool in the end to keep dust out. I suggest you google or ask your mechanic to find out where yours are situated.
      These transmission boxes shouldn’t suck in water if they have the breathers fitted and the seals are intact. However, it is best to keep your vehicle out of the water!
      I suggest you ask your mechanic to show you where all the different plugs are situated as they vary from vehicle to vehicle.

      1. Hi Karin, thanks.
        I know where in my 1995 Troopie the breathers are. Which is not extended to the engine compartment, but to the highest point possible under the bottom plate. Which at a troopie is rather high, but (reconsidering it after reading your blog) not high enough.
        I will consult my mechanic what makes sense. There ís s valve on top.

  3. Best always to send in Jeeves The Butler first. It it’s above his waist then think twice about another route. If it’s above his head then think twice about another butler.

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