How Deep Does Water Need to Be for the Transmission to Get Flooded?
2 Answers
After a vehicle drives through water, transmission flooding generally occurs under the following circumstances: 1. When water reaches above 2/3 of the wheel height: The probability of transmission flooding is around 80% to 90%. 2. When water has reached the dashboard level: The transmission is 100% flooded. Typically, there are two scenarios when a vehicle encounters water: 1. The vehicle is in motion: As long as the vehicle is still moving and the engine hasn't stalled, even if the transmission is submerged, it usually won't get flooded. Although the transmission has a vent hole, because it is operational, there is pressure inside the housing, preventing water from entering. 2. The vehicle is stationary: In this case, the transmission is not working. If the housing is submerged in water, water can enter through the vent hole. In such a situation, the transmission must be inspected, and the transmission fluid must be replaced. If this is not done within 4 hours and the vehicle is brought to a repair shop three to five days later, even after repairs, transmission issues are likely to reappear within five months.
I've been driving for over thirty years and encountered many water crossings. Usually, when the water depth exceeds half the tire diameter, about 30 to 40 centimeters, the transmission is prone to water ingress. There's a small vent hole on the transmission located under the chassis. Once the water level rises above it, water can seep in, causing oil-water mixture and component corrosion. I remember once driving an old Jeep through deep water, and the next day, the gears were sticking. After sending it for repair, it was found that the transmission had water ingress, requiring a major overhaul that cost over five thousand. My advice is to keep an eye on the water depth during crossings—don't go beyond the wheel hub center—and drive slowly to minimize water surges. Before the rainy season, check the vent hole's position. If you hear unusual noises or experience gear-shifting issues after a water crossing, address it immediately. Don't wait until it's completely damaged.
