What Causes a Car Not to Start on Rainy Days?

[LeDonovan]

The reasons a car may not start on rainy days are short circuits and battery issues. Specific details are as follows: Short Circuit: Since most of the vehicle's wiring and pipelines are concentrated in the engine compartment, driving through water may cause internal wiring and pipelines to get splashed with water. Over time, this can easily lead to electrical short circuits and fuel line blockages, with the most direct symptom being the car failing to start. Battery: In low temperatures, a car battery's electrolyte viscosity increases, reducing its permeability and increasing resistance, which lowers the output power. This makes it difficult for the starter to crank the engine to the minimum starting speed, affecting engine ignition. Additionally, the low terminal voltage of the battery results in weak sparks from the spark plugs. Combined with the increased resistance between electrodes due to the denser air-fuel mixture, it becomes difficult to ignite the mixture, leading to engine starting difficulties.

[AdrielFitz]

I've experienced my car not starting on rainy days several times, which is really frustrating. The main reasons are damp air and rainwater seeping into the engine parts, affecting the ignition system. For example, when spark plugs and ignition coils get wet, moisture can cause short circuits, preventing normal ignition. Also, if battery terminals are oxidized or loose, rainwater can cause poor contact, preventing power from reaching the starter. Additionally, water entering the air filter can block the engine from drawing in air, disrupting the air-fuel mixture ratio. I learned from a mechanic that the solution is to park in a covered area or cover the engine hood to prevent this. If the car really won't start, don't panic—wait for the rain to stop or use a dry cloth to wipe key components, but avoid repeatedly trying to start the car to save battery. Regularly checking battery health and the sealing of ignition lines is crucial, especially before the rainy season, to prevent minor issues from becoming major problems. Safe driving requires attention, and it's important to stay calm when facing such situations.

[OLevi]

As someone who knows cars, let me explain this issue. It's quite common for a car not to start in rainy weather, and the root cause usually lies in the electrical system being affected by water. If the ignition coil and high-voltage wires aren't properly sealed, rainwater can seep in and cause short circuits or failures. The battery's voltage tends to drop faster in humid conditions, and corroded contacts may worsen the problem. Excessive moisture in the intake system can also affect the combustion process. I recommend preventive measures like avoiding parking in waterlogged areas and covering the engine. If the car fails to start, open the hood to check for accumulated water and whether any fuses have blown. The solution is to ensure all connections are tight and dry, and avoid forcing the engine to start to prevent damage. For long-term maintenance, keep electrical components clean, upgrade to waterproof accessories, and conduct regular comprehensive inspections to significantly reduce risks. This is related to driving safety and shouldn't be taken lightly.

[StAustin]

When I was learning to drive, I encountered a situation where the car wouldn't start in the rain, and the instructor explained the principle. Rainwater can cause moisture and short circuits in the engine's ignition components, such as spark plugs, preventing sparks from being generated and failing to ignite the engine. If the battery terminals are wet or oxidized, it may also lead to poor contact and failure to transmit electricity. Parking away from puddles in daily use can reduce such problems. If it happens, don't panic—wait for the rain to lessen or try drying the components. If that doesn't work, take it to a repair shop to check the circuit and fuses. Keeping the battery clean and the engine area dry can help.