Waterproofing Your Vehicle

Before we get into this article, it should start with a disclaimer. For all intents and purposes, there is no way to actually waterproof your vehicle. Unless you have a basic diesel motor with minimal electronics, the best you can hope for is to make your 4×4 water resistant. Even then, water will get into your vehicle during extended trips in deep water. Extensive deep water fording causes increased maintenance, wear and tear, and decreased vehicle longevity. This article consists of modifications which minimize vehicle risk and damage from water crossings. Also, this article applies to fresh water. We STRONGLY discourage anyone from doing water crossings in salt water unless absolutely necessary. The corrosive nature of salt water is absolutely devastating to the metal and electronics on vehicles.

Wear and Tear
Deep water conditions are some of the most punishing conditions to which you can subject your vehicle. Using proper fording techniques, most 4x4s are capable of handling water crossings that exceed manufacturers recommendations. However, exceeding that recomended fording depth will greatly increase the wear and tear on your vehicle. If you do deep or frequent water crossings, the time between service intervals on the vehicle should be shortened. These changes need to be done as frequent as daily in extreme 4×4 environments.

High school chemistry taught us that oil and water don’t mix. This is especially critical in 4×4 expedition conditions, where your vehicle is the lifeblood of your expedition. After deep water crossings you should inspect all of the fluids in your vehicle for signs of water contamination. This includes the engine oil, transmission fluid, transfer case oil, wheel hubs and especially the differentials. Contaminated oil will have a telltale milky look to it, and should be changed immediately.

Electrical components are the most susceptable to immediate failure as a result of water contamination. Petrol or gasoline powered vehicles rely on electrical spark from the ignition system to combust fuel in the cylinder. When performing a water crossing, it is easy to get spark plugs, wires or distributor wet, incapacitating the vehicle.

By contrast, diesel engines ignite fuel by means of compression. This means that diesel motors do not rely on an ignition system to run. Due to this increased simplicity, diesel-powered vehicles are typically better candidates for deep water usage. This added simplicity can also mean less on maintenance and less opportunity for mechanical failures, making diesel-powered vehicles ideal candidates for most expeditions and overland trips.

Here in North America, however, diesel technology is just beginning to catch on in non-industrial applications. With only a handful of exceptions (e.g. CRD Jeep Liberty, V10 VW Touareg) most overland vehicle candidates available stateside are petrol (gasoline) powered.


Proper water crossing techniques are absolutely critical, and easily the most important part of a successful water crossing. Prior to attempting the water crossing, one should carefully evaluate the conditions. Assess the water for both depth, river bottom conditions and water current. The easiest way to assess depth and river bottom conditions is to scout the crossing on foot. Find a long stick and wade into the water on foot. Using the stick as a probe, search for sudden drop offs, hidden boulders, tree stumps or the like which could impede progress of your vehicle.

Water conditions can frequently change even from hour to hour. In alpine environments, a water crossing that is easily fordable in the morning, may become significantly deeper as the day progresses due to warming conditions and melting snow.

Using proper water crossing technique is critical to maximizing your vehicles fording ability. While it might look “cool” and impressive to drive your truck into the water at full speed, the accompanying big splash is one of the worst things you can do during a water crossing.

In fact, using the wrong technique can cause serious damage to your vehicle even in water far shallower than the factory recommended maximum depths. Below is a video of a brand new Jeep JK Rubicon attempting a water crossing shallower the factory depth of 20 inches. However, the water spray from the tires got into the intake causing the engine to hydrolock … an extremely expensive lesson learned.

The proper technique for a water crossing is to drive through in a moderate, but controlled speed. As a frame of reference, speed should resemble a walking pace. In a Land Rover, we prefer to put the truck into 2nd gear, low range and maintain a slow but consistent speed. At the correct speed, the front of the vehicle will push the water and create a bow wave immediately in front of the vehicle. Behind the bow wave, in the engine compartment, you will create a pocket of lowered water level. As long as you keep a constant vehicle speed, this pocket of air in your engine compartment will continue. Sudden changes in speed, or stopping completely will cause the level of this air pocket to change or disappear, potentially stalling your vehicle. The speed that you will need to travel can vary based upon water conditions. If you are travelling with or against a water current, you will have to vary vehicle speed accordingly.

In an emergency, you can increase your fording depth by placing a garbage bag across the front grille of your vehicle. The bag will help to block water ingress into the engine compartment, furthering the above mentioned air pocket effect. While a garbage bag across the front of the vehicle grille is somewhat unsightly, it gets the job done and can be useful in emergency situations. However, take care to remove the trash bag immediately after the water crossing, as it will block almost all air flow to the radiator.

If during the water crossing, you suspect that water may have gone into the engine, shut the engine down immediately, don’t wait for the engine to stop. Later, we will discuss remedies for a failed water crossing.

Electrical components

The most common cause of failure during a deep water crossing is water intrusion in the electronic components. While inconvenient, this type of problem is relatively easily preventable, and should be the first step in prepping a gasoline-powered vehicle for water crossing. Invest in a tube of dielectric silicone and apply liberally to the ignition system. Common trouble spots include the ends of the spark plug wires (don’t forget both ends) and distributor if your vehicle is so equipped.

Many vehicles have the ECU computer in low and thus vulnerable locations. For example, the ECU on mid-90s Land Rover Discovery and Defenders is mounted either in the passenger seat footwell or beneath the passenger seat. Vehicles which frequently encounter deep water crossings can either relocate the ECU, or waterporoof it by encasing it in a sealable case such as a Pelican case. If you encase it, don’t forget to seal up the mounting and wiring holes with a generous amount of silicone sealant (not the same as dielectric silicone).

Essential items to carry with you in the event of water crossings are some clean shop towels and a can of WD-40. If the vehicle stalls, disassemble the distributor, coil and wires. Inpsect for water ingress, wipe dry and spray liberally with WD-40.

Breather Tubes

An essential upgrade for water crossings is breather tube extensions for the gear boxes. Extensions should be added for transmission, differentials (both front and rear) and transfer case. Commercial kits are available from companies such as Mantec which raise the breather tubes from axles from their vulnerable positions beneath the vehicle to high on the firewall in the engine compartment. Alternatively, you can create DIY breather extensions, frequently for less than $30 using tubes from your local NAPA.

At a bare minimum, these breather tubes should raise the intake point to the top and rear of the engine compartment firewall. Vehicles undertaking extreme water crossings can even go one step further by raising the axle breathers to the top of the snorkel.

While “waterproofing” the drivetrain, it is also critical to fit a wading plug to the clutch bell housing if your vehicle requires it as well as the camshaft drive belt housing. These plugs should not remain in during normal vehicle operations, so it is critical to remember to install them prior to a water crossing and remove them afterwards.

Air Intake and Snorkels

The quintessential upgrade for deep water crossings is the installation of a snorkel or raised air intake. The most severe damage from a failed deep water crossing can occur if your vehicle’s engine ingests water. Since water does not compress and ignite like fuel does, getting water into the cylinders of the engine can hydrolock the engine. This dangerous scenario can bend pushrods, damage pistons and much more. A hydrolocked engine is usually catastrophic, typically requiring a complete rebuild of the engine block. The best way to prevent this (when used with proper water crossing technique) is to raise the air intake from inside the engine compartment to the roof line via a snorkel.

There are a number of high-quality manufacturers of raised air intakes including Mantec for Land Rovers. The Safari Snorkel, imported by ARB USA, is available for most major 4×4 vehicles. When installing a snorkel, it is important to remember to seal all of the junctions, as well as plug the drain holes in the bottom of the factory air intake box if equipped (ie. Land Rover Discovery).

As an added bonus to installing a snorkel, the raised air intake provides cooler and cleaner air when driving in dusty conditions like the desert.

Note: In the event that you do stall your engine mid-water crossing, do NOT restart the engine unless you are absolutely certain water did not get into the water intake. Doing so will hydrolock the engine and likely do CATASTROPHIC damage to the internals of the engine (as seen in the video above).

The easiest way to check if water was ingested into the engine is by disassembling the air intake. If there are signs of water ingress at the mass air-flow sensor (MAF), then precautions (outlined below) should be taken to prevent hydro-locking the engine.

Electrical Fans
The fan on your vehicle creates a pair of challenges when it comes to deep water crossings. First, if the fan comes in contact with water during the crossing, it is likely to spray water throughout the engine compartment. As mentioned previously, this distribution of water on the vulnerable electrics of the vehicle can kill the engine. Second, many late model vehicles come equipped with fans made of plastic, or more occasionally aluminum. It is possible that when the fan blades hit the water, the blades can bend or break, especially into the radiator.

The long-term solution to this two-pronged dilemma is to replace a constantly operating fan with an electrically controlled fan. These fans can be turned off prior to a water crossing, then turned back on after the crossing is complete. A temporary fix available in emergencies is to remove the fan belt which makes the fan turn. The problem with this solution is that on most vehicles, removal of this belt also causes the water pump to stop circulating. This has the potential for dangerous heat build up and damage to the engine. Removal of the fan or serpentine belt should only be done in emergency situations and the belt should be reinstalled immediately after the water crossing.

Stalling out
Even after taking all of these precautions and using proper scouting and fording techniques, it is entirely possible that your vehicle can stall out in the middle of the water crossing or start running rough afterwards. When undertaking any deep water crossing, make a plan and prepare for the event of a failed crossing. In the event of a failed crossing, the following steps should be taken:

First and most importantly, ensure the safety of the occupants and (then) the vehicle. Using proper recovery techniques, move the vehicle to a place where repairing it is safe. To ease vehicle recovery on water crossings where there is a high likelihood of stalling out, it’s a good idea to attach a recovery strap ahead of time. Having the strap ready to throw to the recovering vehicle will make the vehicle rescue much easier.

Second, open the air intake and inspect the air filter for signs of water intrusion. If the filter appears wet, replace it with a new filter. Soak up any other water in the box with a shop towel. Remove the mass air flow sensor and inspect it for signs of water and dry as necessary.

If you suspect that your vehicle has ingested water in the engine, remove the spark plugs and turn over the engine to clear out any water. Be warned that the engine will spray fuel and water a great distance, so make sure that no one is near the engine before turning it over.

Safety Issues

Of course, there are significant variables not only for every water crossing but also from vehicle to vehicle. Caution and judgement should be applied with consideration to the risks of both people and equipment. In a typical overland or expedition situation, careful consideration should be made as to whether a deep water crossing is necessary, or if an alternate route is available. Pangaea Expeditions highly recommends that you receive hands-on training from one of the myriad of professional 4×4 training organizations such as Overland Training, Bill Burke’s Four Wheeling America or Overland Experts.

Water crossing techniques are easily an article in itself, one that we will address at a later time. As with all overland and vehicle dependent expedition situations, it is important to prepare for worst case scenarios.

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