Is it okay to drive a water-damaged car?

[AliyahLee]

It is not advisable to continue driving a water-damaged car. The hazards of a water-damaged vehicle include the following three points: 1. Engine damage: When the water level exceeds the engine's air intake, water can be sucked into the engine cylinders. Since water is incompressible, if the engine stalls due to water ingress and is restarted, the immense reverse force can cause the connecting rods to bend and rub against the engine cylinders, potentially rupturing the engine block instantly, leading to severe engine damage. 2. Transmission damage: Transmissions, whether manual or automatic, have ventilation holes, allowing water to enter. For manual transmissions, prompt cleaning and replacing the gear oil may mitigate major damage. However, automatic transmissions, due to their complex structure and high precision, can suffer from malfunctions if not thoroughly treated. 3. Electrical system damage: Water exposure causes the most significant harm to a vehicle's electrical components. When powered, water can quickly corrode wire connectors, causing short circuits. Severe cases may result in water ingress into various control units, corroding electronic components, which are costly to replace.

[OAubrey]

My car was flooded last year, and the water level reached the door handles at that time. I tried to drive it out, but the engine stalled immediately. When the repair shop opened it up, they found the cylinder block was cracked. In my opinion, the biggest risk of a flood-damaged car is water entering the engine—starting it can cause the piston to compress water, bending the connecting rods, and repairs can easily cost tens of thousands. The electrical system is also a major headache; water and moisture corrode wiring harness connectors over time, potentially causing sudden short circuits six months later. The upholstery, like seats and carpets, grows mold and stinks after being soaked, and it’s impossible to clean thoroughly yourself. So, to be safe, don’t start the engine—just call a tow truck to send it to a repair shop for a full inspection.

[AngeloRose]

Forcing to start a flooded vehicle causes the most damage to the engine. Water entering the cylinders can lead to hydraulic lock, directly deforming the crankshaft connecting rods. Electronic systems also fear water; submerged ECU modules and sensors are like phones dropped in toilets—they may appear dry on the surface but will gradually oxidize and short-circuit internally. The braking system shouldn't be overlooked either, as water in the brake lines reduces stopping power, making driving hazardous. I recommend getting a professional assessment of the flood damage. Shallow flooding might only require removing and drying the carpets, while deeply submerged vehicles often have repair costs exceeding their value, not to mention higher failure rates post-repair—sometimes scrapping is the wiser choice.

[ColinRose]

Whether a flood-damaged car can be driven depends on the water level. If it only reaches halfway up the tires, you can dry it out and inspect it. But if the water exceeds the exhaust pipe, don't risk starting it. Repair shops first use an endoscope to check for water in the engine and test the insulation value of the electrical circuits. The biggest concern is sand and mud getting into the transmission and steering gear, as accelerated wear in these components can lead to premature failure. Even after repairs, be wary of mold inside the car—ozone disinfection often can't fully eliminate it. A friend of mine tried driving a flood-damaged car after drying it for three days, only to have the ABS module fail two months later, costing over 8,000 yuan to replace.