Why Shouldn't You Attempt a Second Ignition When a Car Stalls in Water?
2 Answers
When the engine stalls due to water ingestion, the cylinders are typically already filled with water. Since water is incompressible, the pistons have almost no room to move upward. In this scenario, even if the ignition switch is turned on, the starter motor cannot rotate, potentially causing severe damage to the engine. Moreover, the engine often sustains irreversible internal damage from significant water intake before stalling occurs. Possible reasons for stalling include: 1. At low RPM, excessive exhaust backpressure when the tailpipe is submerged causes the engine to stall. 2. A wet air filter leads to insufficient airflow and stalling (before water enters the intake manifold). 3. Minor or major water intrusion into the engine, resulting in operational failure and damage-induced stalling.
I've been driving for decades and encountered many situations involving wading through water. Once, my car suddenly stalled on a flooded road, and I almost tried to restart it. Luckily, an experienced buddy nearby stopped me in time. When water enters the engine cylinders and you attempt to start the car, the piston compresses the water upward. However, since water is incompressible, it's like forcing something into a full container—the sudden high pressure can bend the connecting rods or even crack the piston and cylinder block. This is called 'hydrolock' damage, and repairing it requires replacing the entire engine, costing at least tens of thousands, not to mention the wasted time. That's why I never attempt to restart the engine in such cases. When wading through water, I always maintain a steady speed in a low gear, avoiding acceleration or braking to prevent stalling. If the water depth exceeds half the tire height, I simply take a detour. Prevention is far better than dealing with the aftermath, so always slow down early and observe water flow when approaching puddles. Some newer cars come with waterproof designs, but older vehicles require extra caution. In short, safety comes first—if the car stalls, cut the power and call for a tow truck. Never take chances thinking it might be fine.
