How Deep Can a Car Be Submerged Before It Cannot Start?

[DiElias]

Generally, if a car is submerged in water to the point where the exhaust pipe is flooded, water can easily enter the exhaust system, causing the engine to stall. Under no circumstances should the car be started at this point, as it could lead to severe engine damage. Additionally, and most importantly, insurance companies will not cover the costs if the car is restarted after being submerged. Precautions for driving through water: When driving through water, avoid high speeds. Instead, use a low gear to enter the water smoothly and proceed slowly to prevent water splashes from wetting the electrical components of the engine, which could cause it to stall. Below is an introduction to vehicle insurance: 1. Compulsory Traffic Insurance: This is a mandatory insurance required by law. Failure to purchase it may result in fines if caught by traffic police. The coverage is limited and primarily benefits third parties, not the owner's vehicle. 2. Third-Party Liability Insurance: This covers the costs of injuries or deaths caused to third parties by the policyholder. It is essential for both the owner's and others' protection. 3. Vehicle Damage Insurance: This compensates for damages to the vehicle caused by natural disasters or accidents. It is recommended for new drivers. 4. No-Deductible Insurance: An additional coverage that transfers the policyholder's liability to the insurance company, reducing the owner's losses. If both Vehicle Damage Insurance and Third-Party Liability Insurance are purchased, it is advisable to also get No-Deductible Insurance.

[AthenaLee]

Last time my car stalled in floodwater, the mechanic told me the key factor is the air intake position. When water reaches the wheel hub center (about half the tire height), it can enter the engine through the intake pipe. Attempting to start the engine at this point may bend the piston connecting rods, with repair costs starting from five figures. Even more dangerous is the electrical system – when water reaches the lower edge of the doors, the wiring harness connectors will absorb large amounts of water, potentially causing a short circuit and burning out the ECU circuit board. Now whenever driving in heavy rain, I always keep a close eye on the air intake height below the front grille – that's the absolute lifeline water level.

[NaomiMarie]

In car modifications, we often encounter waterlogged vehicles, and the worst scenario is when customers insist on starting the engine. The lower edge of the engine compartment is about 30 cm from the ground. When the water level rises above this point, the oil dipstick hole and transmission vent will be submerged. The body control module is usually installed under the driver's seat, and once the water reaches the floor carpet, it's doomed. The most tragic case I've seen was when the water level just reached the bottom of the door, and the engine seized completely after the owner restarted it three times. Remember, if the water exceeds the wheel hubs, shut off the engine immediately, disconnect the battery negative terminal, and take photos of the waterline inside the car for insurance claims before calling a tow truck.

[LeEden]

Veteran Mechanic's Advice: Whether you can start a car after flooding depends on whether the waterline exceeds the midpoint of the exhaust pipe. If the water submerges the exhaust pipe outlet, the exhaust resistance surges, and water flowing back into the cylinders can cause total engine failure. Hybrid or electric vehicles face even greater risks—if the underbody battery pack is submerged for just 10 minutes, the BMS system may automatically lock down. Another often overlooked component is the starter motor; even if the water only reaches the wheel arches, moisture on the starter coils can cause a short circuit and smoke. I’ve seen too many cases where owners tried to save on towing fees by forcing a start, only to end up with repair costs ten times higher.