What Causes Water Leakage in the Passenger Side During Rain?
2 Answers
Reasons for water leakage in the passenger side during rain: 1. Clogged sunroof drainage holes. If the sunroof drainage holes are blocked during rain, water cannot drain and will seep into the car; 2. Aging sunroof rubber seals. Plastic components harden and degrade over time, reducing the seal's effectiveness and causing leaks during rain; 3. Clogged air conditioning drainage holes. If these are blocked, condensation from the evaporator cannot drain and may leak from the passenger side; 4. Poor door sealing. Incorrectly installed or aged door seals can reduce the car's waterproofing, allowing water to enter during rain; 5. Clogged door drainage holes. Due to their low position, these holes can easily get blocked by mud, preventing rainwater inside the door from draining and causing leaks into the car.
Last time I found water accumulation in the passenger side, and upon careful inspection, I discovered it was due to clogged sunroof drainage holes. My car is often parked under trees, and those small twigs and rotten leaves completely blocked the drainage holes. When it rained heavily, water seeped in through the ceiling seams. Actually, aging and cracked door seals are also a common cause, especially for cars over ten years old. Once the rubber seals harden, they can't keep rainwater out at all. Additionally, if the air conditioning drain pipe comes loose or gets clogged, all the water produced during cooling flows under the floor mats. The most troublesome issue is leaks from the car body's welded seams, which only a professional can diagnose. If you notice water ingress, I recommend checking the carpets for mold first. Addressing it promptly can save a lot on repair costs.
