How Long After a Car Gets Flooded Can You Start the Engine?

[VonEleanor]

When a car gets flooded, first check if the air filter on the engine has been submerged. If not, you can start the car at any time. Below is relevant information about starting a flooded car: 1. Water Level: If the water level does not exceed the engine, since the engine's cylinder and block sealing performance from the oil pan are very tight, water entering the engine's interior and causing damage can only occur if the water level remains above the engine for an extended period. 2. Hazards of a Flooded Car: The air resonator box is located between the air intake and the intake hose. Its function is to reduce intake noise, stabilize airflow, and prevent small amounts of rainwater from entering the combustion chamber. It is generally positioned between the front wheel and the front bumper, where water can easily reach. Once the resonator contains water, a large amount of water can be sucked into the combustion chamber when starting the engine, and the incompressibility of water can cause catastrophic damage to the engine's connecting rods. This is the fundamental reason why starting a flooded engine is strongly discouraged. The starter motor is usually installed at the lower end of the engine block and can easily be submerged. Since the starter does not have the engine's high airtightness, water can quickly penetrate its interior. Starting the engine in this condition may cause an internal short circuit in the starter, resulting in it burning out.

[ColtonFitz]

I've been driving for over twenty years and have encountered several instances of water ingress, ranging from heavy rain flooding up to the door handles to accidentally wetting the hood during car washes. After a car gets water inside, you must never rush to start the engine. The waiting time varies from person to person, but I recommend waiting at least 48 hours or longer, depending on the extent of water ingress. The last time my car was flooded up to the wheel height, I waited a full three days before towing it to the repair shop. If water gets into the engine, starting it will compress the water, causing a water hammer effect that can deform the pistons or even break the connecting rods, leading to repairs costing thousands of dollars. Additionally, if water enters the electrical system, such as the ignition wiring or the ECU computer, starting the engine can immediately burn them out. So don't skimp on towing fees—call for rescue immediately and have the car transported to a professional shop where they can dry the interior with compressed air. For prevention, avoid driving through puddles and check the seals after rain.

[Roxanne]

I'm a tinkerer who loves mechanics and has taken apart many engines. The time it takes for a car to start after being submerged isn't fixed, but it's best to wait a few days and not test your luck. Engines are designed to compress air, but water isn't compressible. If you try to start it, the piston pushing up against the water can bend the connecting rod, causing fatal hydraulic lock. Electrical components are also ruined: spark plugs short-circuit when wet, circuit boards fry, and fuses blow. I remember my friend tried starting his car just an hour after it got flooded, and the engine was totaled—insurance wouldn't cover it. My advice is to immediately disconnect the battery and tow it to a repair shop. For prevention, avoid parking in deep water and check the engine bay after heavy rain. Patience is better than replacing an entire engine.

[StZachary]

I just bought a new car not long ago, and during that heavy rainstorm, the water level rose up to the carpet height. I was panicking, afraid that starting the engine could cause serious trouble. Experts say to wait at least 24 hours after water ingress, and even longer if the water level was deep. I waited a full day before calling a tow truck. After being towed to the shop, they used a dryer to handle the situation. If you start the engine immediately, water entering the cylinders could cause the engine to seize, potentially leading to a rupture, and it's also prone to burning out the wiring. Safety first—don’t try the ignition button. Afterwards, make sure to clean up any water traces inside the car to prevent mold growth.