What Causes Water Leakage in a Car Roof?
2 Answers
Introduction to the causes of water leakage in a car roof: 1. Sunroof leakage: Sunroof leakage generally occurs in two situations. One is when small sand particles or dust clog the sunroof drainage channel. The other is when the sunroof sealing strip is "lifted" or displaced. Therefore, it is advisable to regularly clean the sunroof to keep the drainage channel clean. Additionally, during car washes, use high-pressure air equipment to blow air in the direction of the drainage pipes to remove dirt inside the pipes. 2. Failure of car waterproof adhesive causing leakage: Leakage usually occurs at the openings of doors or the trunk. The main reason for this is often the waterproof strip, which may be defective, aged, or cracked, allowing rainwater to seep in. Reapplying adhesive specifically for waterproof strips can completely prevent leakage. If rainwater seeps in around the door, the issue is likely with the surrounding waterproof strip. Check for any cracks or peeling. The waterproof strip around the door can easily become misaligned. If water enters the car, the first thing to check is the door waterproof strip. 3. Clogged drainage pipe causing interior leakage: The most common cause of interior leakage is a clogged drainage pipe under the front windshield. Infrequent car washing or long-term parking under trees can lead to dust, leaves, mud, and other debris being washed into the drainage pipes by rainwater, eventually clogging them. This obstructs drainage, causing rainwater to backflow into the car during heavy rain, resulting in leakage. Therefore, it is essential to regularly clean the pipes and inspect damaged components. 4. Failure of floor rubber plugs causing leakage: While rainwater usually leaks from above, it can also seep in from below. The reason for this is the rubber plugs on the floorboard. There are several holes in the floorboard, with rubber plugs embedded from above. If these plugs become misaligned, the interior becomes directly connected to the ground, allowing rainwater to seep in from below during heavy rain. If the floor gets wet, this should be the first area to suspect.
I found that most roof leaks are caused by the sunroof. The sunroof drain tubes are prone to clogging with leaves and dust, preventing water from draining properly during heavy rain, which then seeps into the cabin. My old car had this issue—when I took it apart, I found the rubber seals had hardened and cracked. For vehicles with aftermarket panoramic sunroofs, improper sealing during installation is also common. Leaks from aging waterproof pads on roof rack screw holes are even more hidden. I only realized this when I saw small rust holes on a colleague's roof. Before the rainy season, remember to clean the sunroof drainage channels and apply some conditioner to rubber parts to extend their lifespan. Those who are handy can use thin wire to clear the drain tubes, but it's best to have a professional repair shop conduct a thorough inspection.
