Can Water Enter the Transmission When Driving Through Water?

[SanDante]

After driving through water, the transmission, differential, or front/rear axles and differential may take in water. Generally, transmission water ingress is mainly caused by the following two situations: Water level exceeds two-thirds of the wheel: If the water level surpasses two-thirds of the wheel, the probability of water entering the transmission is around 80% to 90%. If the water has reached the dashboard level, the transmission is 100% flooded. Water splash during oncoming traffic: When encountering oncoming vehicles, excessive road water can lead to water entering the transmission. Once water enters the transmission, the performance of the transmission fluid will be affected. The performance of the transmission fluid will also degrade, causing the clutch plates to slip.

[DelEdward]

When driving through water, it is indeed possible for water to enter the transmission. Let me explain. Transmissions typically have a vent hole designed to regulate pressure changes. However, if the water level rises above the wheel hubs, the high water pressure can easily force water back into the transmission. This is especially true when driving through standing water after heavy rain—if the water reaches below the hood, the transmission vent becomes a direct entry point. Automatic transmissions are more prone to water ingress than manual ones because they require higher sealing standards. Once water enters, it mixes with the transmission fluid, leading to lubrication failure, component rust, and even complete damage. I think many car enthusiasts overlook this issue, focusing only on the risk of engine water ingress, unaware that transmission repairs can be just as costly. Prevention is simple: avoid driving through deep water, generally keeping the water level below half the height of the wheels. After driving through water, promptly check and change the fluid, or visit a professional shop to test for water residue with specialized equipment. Early intervention can save significant repair costs.

[SanKaleb]

Last week I drove through a flooded area, and after the car stalled, the transmission started making clicking noises. It turned out water had gotten inside. The water level hadn't even reached the front bumper, but the transmission vent became an entry point for water; the repair cost me several thousand yuan afterwards. If you frequently drive on wet roads, be careful not to exceed a wading depth of 20 cm. Manual transmissions are relatively more durable but can still be affected. After water ingress, the transmission oil will emulsify and turn white, drastically reducing its lubricating performance and accelerating gear wear. Regular maintenance should include periodic transmission oil changes. After driving through water, stop immediately to check, and don't force the car to move, as this could burn out the entire system. A friend of mine neglected this and ended up with a ruined transmission. It's advisable to develop the habit of avoiding deep water areas and keep a simple tool in the car to check oil levels.

[McHannah]

Back when I first started driving, I went through a shallow puddle and the transmission started acting up. Actually, water damage to transmissions poses significant risks, especially in older vehicles with worn seals. During water crossings, if the water level is too deep, water may seep in through the vent holes, causing internal corrosion. As a novice driver, I think it's important to be cautious: if the standing water reaches thigh level, it's better to detour or proceed slowly; after driving through water, pay attention to any abnormal transmission noises and get it repaired promptly to prevent further damage. Most vehicle manuals warn against submerging the exhaust tailpipe.