Is There a Problem with Leaving the Car Hood Open in the Rain?

[GageLynn]

Leaving the car hood open in the rain can have negative effects on the vehicle. When it rains, with the hood open, water can enter the air filter through the gaps between the hood and headlights. If the drainage valve's function is compromised, rainwater may enter the engine through the intake pipe, causing the engine to fail to start. For minor cases, you can remove the distributor cap, dry it with a tissue, and reinstall it. For severe water ingress, professional repair is needed. Here are additional steps to handle a car engine stalling due to water ingress: 1. Open the engine hood and disconnect the cylinder wires. 2. Remove the spark plugs and then start the engine. Water in the engine cylinders will be expelled through the spark plug holes. 3. Hold the key in the start position for 5 seconds, then release. Wait 10 seconds and start the engine again for 5 seconds. Repeat this process three times to effectively remove all water from the engine.

[MadelineFitz]

Last time my neighbor Lao Wang forgot to close the hood when parking, and it got drenched in rain all night. When I helped him check it, I immediately spotted issues. Those wire connectors and fuses in the engine bay are most vulnerable to water—prolonged exposure can cause short circuits. If you start the car under such conditions, it might even fry the ECU module, costing thousands to repair. Plus, the acidity in rainwater corrodes metal parts; rusty battery terminals leading to poor contact would be disastrous. The most critical risk is if water enters the intake pipe—starting the engine could hydrolock it, requiring a major overhaul. That’s why I always remind beginners: before leaving the car, double-check that the hood is securely closed. If it does get rained on, don’t rush to start the engine. First, wipe away visible water with a dry towel, then drive to a repair shop for thorough drying—that’s the safe way.

[LaDamian]

With over twenty years in auto repair, I've seen countless cases of open hoods. Rainwater seeping into the engine compartment wreaks havoc on the electrical system first. Starters and alternators get soaked, burning out their coils, while oxidized wiring connections lead to poor contact. The worst scenario is water damage to the ECU, paralyzing the entire control system. Rust on metal parts is the least of concerns. Once, a customer's turbocharger rusted solid from water ingress, costing over 8,000 yuan to replace. However, brief exposure to light rain isn't catastrophic. I always advise owners: if caught in rain, release the hood strut to let the compartment air dry for two days before driving. For regular parking, facing away from the wind helps keep rain from drifting into the engine bay.

[SamanthaRose]

Last year, after lending my car to a relative, I found the hood wasn't closed properly when it came back, and it got soaked in heavy rain. Opening it up, I was shocked to see water even inside the air filter box. The mechanic said there could be three consequences in such cases: electrical shorts triggering fault codes, accelerated rusting of metal parts, and the most dangerous being water entering the cylinders through the throttle body. Now, every time I turn off the engine, I habitually press the hood twice to confirm it's shut. Short-term exposure to rain isn't a major concern, but remember to clear any accumulated water, especially around the battery and fuse box areas. If parked outdoors long-term, it's best to buy a car cover or use plastic sheeting to protect the engine bay – repairing wiring is far more expensive than replacing a light bulb.