How Deep Does Water Need to Be for the Transmission to Get Flooded?
2 Answers
If the water level exceeds two-thirds of the wheel height, the probability of the transmission getting flooded is approximately 80% to 90%. If the water has already reached the dashboard level, the transmission is 100% flooded. Additional details are as follows: 1. Do Not Start the Engine After Wading: Avoid starting the engine after wading through water. Pay attention to the water depth and refrain from restarting the engine. Even with flood insurance, insurers will not cover damages caused by restarting the engine. Additionally, the transmission, differential, or front/rear axles may get flooded. 2. Impact of Transmission Flooding: When water enters the transmission, the performance of the transmission fluid is compromised, leading to reduced effectiveness. This can cause clutch slippage, increased fluid temperature, and even the generation of steam or boiling of the fluid-water mixture. These viscous substances may also accumulate in the valve body, causing blockages and affecting the transmission control system.
I remember driving through a puddle during heavy rain once, and the trouble caused by water entering the transmission was significant. Generally, when the water depth exceeds half the height of the tires, the transmission is prone to water ingress—for example, over 30 cm—because the transmission vent tube is located under the chassis, and high water levels can flood it. After water enters, the oil turns milky white, lubrication fails, transmission noise increases, and bearings and gears may be damaged, costing at least several thousand yuan to repair. That time, I didn’t pay attention in a deep water area where the water almost reached the center of the wheel hub, and I ended up spending a lot on repairs. Later, I learned my lesson: before driving through water, I measure the depth with a stick, maintain a low and steady speed, and avoid sudden acceleration or braking. If water does enter, tow the car for inspection immediately—don’t delay. Safe driving is more important; don’t take risks to save time.
