What Are the Common Faults After a Transmission is Submerged in Water?
3 Answers
Common faults after a transmission is submerged in water include automatic transmission fluid deterioration, clutch damage, transmission slipping, and transmission oil leakage. Automatic Transmission Fluid Deterioration: Water entering the automatic transmission directly causes the transmission fluid to deteriorate and oxidize, reducing its friction coefficient. As a result, the vehicle components lack sufficient friction, leading to symptoms such as jerking, impact, and slipping in the automatic transmission. Clutch Damage: Water entering the automatic transmission not only damages the transmission fluid but is also highly detrimental to the clutch plates. If the clutch plates are submerged in water and cannot be repaired, replacement is the only option, which increases the corresponding repair costs. Transmission Slipping: During driving, if the engine revs up but the vehicle speed does not increase, accompanied by a feeling of overall weakness, this is often caused by burnt clutch plates. Water entering the transmission due to external factors, such as coolant mixing with oil or water entering through the transmission vent cap, can cause abnormal transmission operation. Transmission Oil Leakage: Oil seeping from the transmission housing or oil pan can be caused by aging seals leading to poor sealing or manufacturing defects resulting in pinholes in the housing.
A few days ago, my neighbor's SUV developed transmission issues after driving through standing water. When I helped inspect it, I noticed several typical problems. Water entering the oil pan can emulsify the transmission fluid, turning it milky white, which drastically reduces lubrication effectiveness, causing harsh gear grinding noises. In severely flooded vehicles, even the gear shift lever can get stuck, feeling like it's jammed with pebbles and impossible to move. The most troublesome issue is rust forming on the precision components inside the valve body—once the electronic module shorts out, the entire shifting logic goes haywire. For instance, the car might suddenly lurch forward even when it's in Drive (D) mode. If you detect a burning smell or see the gear warning light on the dashboard, never force it to drive—calling a tow truck is the only solution. Repairing a water-damaged transmission is extremely costly: just disassembling and cleaning the valve body can cost 3,000–4,000 RMB, and in severe cases, the entire assembly might need replacement. So when you see deep puddles on rainy days, it's best to detour around them.
As a veteran driver with twenty years of experience, I've had my transmission flooded three times. The destructive power of water is beyond imagination—gears and bearings develop invisible rust spots, making gear shifts feel as rough as stepping on sand while changing gears. Even more terrifying is when water mixes with the clutch plates; cars with wet dual-clutch transmissions shake violently during gear shifts, as if going over speed bumps. Once, after driving through water, I forgot to inspect it and drove for half a month before noticing a 30% spike in fuel consumption. The mechanic drained half a cup of mud from the fluid. I recommend checking the transmission breather valve after heavy rain—this small rubber hole can let water seep in under high water pressure. It's best to change the oil within 48 hours of driving through water, rather than waiting for problems to arise. Otherwise, the repair costs could amount to two years' worth of fuel expenses.
