Posted on 9/25/2026

Driving through floodwater can damage much more than the engine. The transmission sits low in the vehicle, and water can reach seals, vents, electrical connectors, and cooler lines long before the water looks deep enough to cause a problem from the driver's seat. The risk depends on how high the water was, how long the vehicle stayed in it, whether the transmission was hot, and whether water found a path inside. If a vehicle has been through standing or moving floodwater, we would rather inspect it early than wait for shifting problems to appear later. Water Can Enter Through the Transmission Vent Automatic transmissions need a vent because the fluid and air inside expand as the unit heats up. That vent is normally high enough to stay dry during ordinary rain and road spray, but floodwater is different. If water rises high enough around the transmission, it can enter through the vent and mix with the fluid. Once that happens, the transmission loses the clean lu ... read more