Manufacturers build vehicles with water resistance in mind. They can operate in a variety of wet conditions, such as heavy rain. Driving through standing water is another matter. It is not of matter of how much water it takes to damage the vehicle. It is shocking how little water it takes to cause considerable damage.
Water will damage almost any automotive component.
Included are starters, universal joints, wheel bearings, differentials and especially automatic transmissions. On a vehicle, engineers vent all lubricated parts to the atmosphere. This allows pressure that develops, to escape. The vehicle makers’ design vents, to resist normal amounts of moisture, as with rainfall. They design none of these components to operate under water.
People often think, driving through a moderate amount of water does no harm.
If the engine does not stall, the driver may think things are okay. We may drive down a flooded street, make it to the other side and assume all is well. Several future problems are likely occurring.
First is the water surge, which occurs when the vehicle moves through water. The engine compartment is open and water rises into this area. This surge may be a foot or higher than the surrounding water. Worse is the wake generated by passing vehicles. The combination can easily flow over a transmission and into the vent.
The vent on this automatic transmission is typical and water damaged the transmission. They install a small, protective hose in manufacturing. This helps, but will not keep a wash of liquid out. Water flowing over the transmission will still enter. Time causes dry-rot and improper service will damage hoses and caps, designed to help protect vents. Finding these hoses out of place, or missing, is very common. This makes the situation much worse, but even with the hose in place, water can still enter.
Once water enters the component, lubricant begins to fail. Water soluble glue bonds the clutches in an automatic transmission together. They design it to resist transmission fluid, which is petroleum based. Water will dissolve the linings, and total failure will result.
If water remains in the transmission, for a short time, rebuilding the unit is the only viable repair.
Flushing the fluid or even a proper service, will not reverse the damage. Rust starts to attach bearings and machined surfaces in the transmission. Rust pits result in bearing failure, and the metal generated destroys solenoids and clog valve-body passages.
After exposure to water, some automatic transmission may last longer than others. Many fail almost immediately and others may last several months. In each case, a major repair is the result. The only prevention is not driving through standing water.
An SUV is no match for standing water. People often think that an SUV or trucks, are more water-resistant than other vehicles. This is not so. We will submerge the starter, automatic transmission, universal joints and differential when crossing shallow water. Wheel bearings allow water to enter past the seals. A lack of immediate symptoms, means very little. A total failure may take months to occur, but if water remains, the result is inevitable. Trucks are not more water resistant than other vehicles.
Even very large trucks are susceptible to water damage.
Driving through standing water destroyed the differential, in this one and a half ton truck. Emulsification of the lubricant allowed the bearings and gears to fail, costing several thousand dollars in damage.
Driving through standing water will damage a vehicle. Finding an alternate route or parking the vehicle, until the road clears, may save thousands in repair. Driving a vehicle through water means, we should inspect all components and fluid very soon. Some parts will not be serviceable. For instance, we cannot take apart sealed wheel bearings. Replacing the fluid, in those parts that are serviceable, may prevent damage.