What are the reasons for water leakage inside a car?
3 Answers
Water leakage inside a car can be caused by: 1. The radiator cap not being fastened properly; 2. Engine oil emulsification; 3. Poor quality of the radiator; 4. Loose door seals, leading to water leakage through the doors; 5. Leakage at the radiator rubber hose connections; 6. Clogged sunroof drainage channels or displaced sunroof sealing strips. The solutions for water leakage inside a car include: 1. Check if the radiator cap is not fastened properly; 2. Replace the engine oil; 3. Replace with a qualified car radiator; 4. Replace the door seals; 5. Inspect the radiator rubber hose connections for leaks; 6. Clean the sunroof drainage channels; 7. Adjust or replace the sunroof sealing strips.
A couple of days ago, I found water accumulation under the front passenger footwell of my car, and after some troubleshooting, I realized it was caused by the sunroof. Nowadays, new cars come with panoramic sunroofs, but if leaves or tree seeds clog the drainage channels, leaks can easily occur. Additionally, aging door seals or improperly sealed roof rack mounting holes can allow rainwater to seep through the gaps. The air conditioning system is especially troublesome in summer—if the evaporator drain pipe gets clogged with mud, condensed water can backflow into the cabin. I remember after a heavy rain, I noticed water stains around the edges of the rear windshield, which turned out to be a crack in the sealant. These areas need regular inspection, or else your car might turn into an aquarium during the rainy season!
After years of repairing cars, the most common water leakage issues occur in four areas: clogged sunroof drain tubes with mud, detached door waterproof membranes, deformed trunk seals, or cracked AC drain pipes. Vehicles frequently parked under trees are especially prone to water accumulation as fallen leaves block drainage channels. Some accident-repaired cars with improperly sealed windshields may also experience water seepage. I recommend owners clean sunroof tracks quarterly and listen for air leaks when closing doors to check seal integrity. During car washes, pay special attention to flushing door bottom drainage holes—neglecting these small areas could require dismantling entire interior panels for repairs.
