Why Can't You Restart a Flooded Car?
3 Answers
The reason you should not attempt to restart a flooded car is that it can cause severe engine damage, and insurance companies typically refuse to cover such claims. Here are two key precautions for driving in rainy conditions: 1. Maintain a steady, slow speed: Avoid unnecessary lane changes. Rainwater accumulation on side mirrors and windows obstructs visibility, increasing the risk of sideswipe accidents - the most common rain-related collisions. When reduced visibility makes it difficult to assess lane change safety, promptly activate hazard warning lights to alert following vehicles. 2. Assess water depth: Before crossing flooded areas, always verify the water depth. Never attempt to drive through uncertain water levels. When crossing confirmed passable sections, maintain low gear and consistent speed to preserve engine power. Avoid accelerating through water, as this significantly increases stalling risks.
I've been driving for twenty years and have seen several cases of waterlogged cars. Once a car is waterlogged, never attempt to start the engine, or the repairs will become a huge headache. If water enters the engine, when you try to start it, the piston compresses downward, but water can't be compressed, which can lock up the internal engine components, causing the piston rod to deform or even break. A friend of mine once learned this the hard way—after attempting to restart, the engine was completely ruined, costing tens of thousands to replace. The first thing to do after water exposure is to turn off the power, let the engine cool, and then call a tow truck to take it to a repair shop to check for water ingress. Don’t underestimate even a small amount of water—besides the engine, electrical circuits can short-circuit and damage safety systems. Simply put, avoiding a restart can save you unnecessary expenses and ensure safe driving. Don’t gamble with luck.
When repairing cars, I always remind car owners not to rush to restart a waterlogged vehicle. If water enters the engine block, ignition can cause a sudden increase in water pressure, damaging mechanical components and leading to bent connecting rods or even complete engine failure. Modern engines operate by compressing air, and water ingress can lock the crankshaft. Repairing such issues often requires disassembling the engine for cleaning or replacing parts, which is time-consuming, labor-intensive, and expensive. The best course of action after waterlogging is to immediately turn off the engine, exit the vehicle, and check the engine compartment for water traces to prevent battery short circuits that could cause a fire. Towing the car to a professional shop for water drainage can save it. In fact, driving slowly through deep water during rainy days and taking preventive measures beforehand is much better than dealing with the aftermath.
