Water Crossing How To

Crossing Over Water in a 4X4

Many off-road drivers have found out the hard way that water crossings in real life isn’t as easy as those we see in the movies or in television. In fact, attempting to do a water crossing can be one of the most expensive mistakes you can make regarding your 4x4. The damage can be as simple as a wet carpet or floor or as complicated as a damaged engine and radiator.

A rule of thumb when making water crossings is not to attempt one when the water level is higher than the top of the wheels. All that rubber weather stripping you see on the edges of your car’s doors are there to lessen wear and tear and not to make your car waterproof. Moreover, it is also a recommended practice to keep the recovery gear above your things before making a water crossing. This is so that you won’t have to snorkel in order to retrieve it when you get stuck in the middle of the crossing.

Walking the Path

One of the most obvious things you should do before making a water crossing is to get out of the vehicle and walk the path that your vehicle is going to take. This may take the glamour out of using a 4x4 in crossing over water and it may require you to cross the same stream twice but keep in mind that this could be the only thing that would prevent you from having to pay a hefty sum in order to get your vehicle repaired.

Traverse the path where the wheels themselves are going to take. Make sure you bring along markers to mark dangerous or deep areas that you must avoid when doing the actual crossing. Check the currents too. If the current is too strong for you to cross the river, chances are, your 4x4 won’t be able to make it too. Check for potholes or hidden rocks and mark them accordingly. Keep in mind that a single pothole may cause your hood to be submerged under water and thus cause hydro locking and engine damage.

Lastly, walking the path that your car is going to take and marking dangerous spots along the crossing gives your gearbox, axles and differentials time to cool down before you do the actual crossing. The benefit of this will be explained further in this article.

Diff Breathing and Air Pressure

Directly plunging into the water without giving the axles time to cool down can cause water to permeate the diffs. This is because a hot axle will cool down very rapidly when exposed to water and thus result in the lowering of pressure along the axle and diff housing. This reduction in air pressure then forces air to be drawn from the breathers. This can be avoided somewhat by elevating the diff breathers further up the chassis using plastic tubing. Sudden drops in pressure by sudden cooling of the axles may still cause water to enter via the axle seals if the pressure is not equalized quickly so it is a good practice to allow the vehicle to cool down before attempting a water crossing.

Air Intakes and your Engine

Air intakes are direct paths to your car’s engine and while they may serve to cool down your engine, they can also become convenient pathways for water to directly enter the engine. Water plus engines in a water crossing may result in hydro-locking or in other words, damaged crankshafts, valves and pistons. A good rule of thumb when it comes to air intakes and crossings is never to attempt water crossings when the water level is higher than the air intake.

If you plan to do water crossing in a regular basis, then it will be a good investment to fit a snorkel in your 4x4’s roofline to serve as the air intake. But although this may serve to prevent water from entering the engine through the air intake, it doesn’t mean that you can drive over any body of water with a depth lower than the snorkel! A 4X4 is after all still a car and not a sub.

Protecting the Engine

To further protect the engine, a tarp across the front of your 4x4 as well as sufficient crossing speed is needed. For one, the tarp will minimize the water entering the engine bay by creating a bow wave in front of the vehicle. This bow wave however can only exist as long as the car is traveling at a certain speed. Fail to maintain the needed speed for the bow wave and the radiator fan will spray water all over the ignition system and this may result in a stalled vehicle. Moreover, with enough water in the engine compartment, the radiator fan may act more like a propeller and cut a nice hole in your radiator.

To prevent a stalled engine and a wet ignition system, you can spray water repellent over it before doing the water crossing. If bad luck still finds you stuck in the middle of the crossing with a stalled engine, check the water level outside the car first and see if you can open the door without flooding the carpet. If the water level is above the door bottom, use the window instead in getting out of the car.

Radiator Fans and Propeller Blades

If you stop to think about it, your car’s radiator fan is not much that different from a speed boat’s propeller blade. In fact, if you don’t take this into account when doing a water crossing, your car’s radiator fan will indeed turn into a propeller and cut its way forward into the radiator.

To prevent this from happening, check the type of radiator fan installed in your car before doing a water crossing. Turn off the engine and check if the fan still turns easily. If yes then it is probably safe to keep the fan belt on. If it’s locked, then you will have to take the fan belt off.

Crossing Over

When the time comes to do the actual crossing, don’t forget to un-strap your seatbelt and roll down the windows. The second gear usually provides the best speed needed to create and maintain the bow wave in front of your vehicle. Keep the RPM within the range of 1500-2000 as too high will scatter water everywhere and too low will flood the engine bay. Follow the markers you have set as best as you can and keep your foot off the clutch as much as possible while driving across as this may introduce water between the flywheel and friction plate.

Remember not to use the accelerator too much when the wheels start slipping as this will only aggravate the problem. Ease off on the accelerator instead and hope the wheels regain traction. If the car sputters and dies in the middle of the crossing, put the gear in neutral without using the clutch, cross your fingers and hope the engine restarts. If it does, then luck is on your side and, hopefully, you will reach the other side without any other incidents. If not, then its time to scramble outside through the window and break out the recovery gear.

After the Crossing

Upon successfully doing a water crossing, don’t forget to check the diff oil for water contamination. This can be easily done since water is heavier than oil and thus will settle near the drain plug. Cool off the engine first then let some of the oil drain into a clear glass. If there’s water present or if the oil is milky, then you would have to drain enough to ensure that most of the water is drained. Change the oil too at the earliest opportunity.

Second, recheck every part of your 4x4 that has been submerged under water like the gearbox, engine oil, and transfer case, bar mounts or electric winches. Strip them and grease them accordingly. This prevents them from seizing up and getting rusty and saves you a lot of money for repairs in the long run.

With all these tips and more, you should be able to do water crossings safely and without incurring expensive damage on your car. Remember, while water crossings may be fun, if you don’t want to invest in the small preparations and after crossing maintenance, you may end up paying more than you’re ready to spend.