Why Do the Welding Points in the Trunk Drainage Channel Rust?
3 Answers
Rust on the welding points in the trunk drainage channel is caused by high-temperature oxidation. Detailed explanation of the reasons for rust on the welding points in the trunk drainage channel and solutions are as follows: The high temperature generated during welding promotes rust formation at the welding points, as it damages the anti-rust layer; humid air also accelerates oxidation and rust; potential issues with the factory anti-rust coating process; whether the trunk drainage channel has undergone repairs; and the parking environment of the vehicle. Solutions: Applying anti-rust paint: For steel structures that have undergone anti-rust treatment, the welded areas should be coated with anti-rust paint to ensure protection and maintain a uniform decorative effect. The type of anti-rust paint should match the original coating used on the steel structure. Common options include epoxy zinc-rich primer, red lead anti-rust paint, and iron red alkyd anti-rust paint. During application, the welded areas, fusion zones, and heat-affected zones must be thoroughly cleaned by grinding to remove welding slag and existing paint. Then, select the appropriate anti-rust paint based on environmental factors like temperature and humidity; Acid pickling and passivation: Metal passivation involves using strong acids or similar substances to chemically react with the metal surface, forming a dense passivation film for rust protection.
I've repaired quite a few trunk issues on cars before, and this kind of rusting at weld points is actually quite common. It's mainly due to welding process problems—some cars don't have their weld points treated carefully enough during manufacturing, with uneven application of anti-rust paint, making them prone to rust over time. There are also everyday usage factors, like rainwater seeping into trunk gaps or winter road salt clinging to the weld points, which can accelerate rusting. Additionally, older vehicles with aged rubber seals allow more moisture to seep into the channels. If you notice this issue, address it early: first, sand off the rust spots thoroughly, then apply anti-rust primer and topcoat. It's best to regularly clean out leaves and debris from drainage channels to keep them dry and well-ventilated, especially in coastal areas where salt spray corrosion is a bigger concern.
Having driven for ten years, I've also encountered rusting at the trunk's welding spots. Observation shows it's mainly related to the environment: when driving in the rain, mud and water splashed up by the wheels can reach the lower rear of the vehicle, and the drainage channels, being low-lying, tend to collect water. Additionally, if water from high-pressure car washes sprayed into crevices doesn't dry promptly, moisture gets trapped in the channels. Moreover, in northern regions, winter de-icing agents are particularly corrosive, and repeated soaking in these can cause metal welding spots to rust. It's advisable to open the trunk and dry the channels after each car wash. If rust has already formed, avoid scraping with a knife or using strong acid rust removers, as these can damage the primer. Using WD-40 spray to soften the rust before wiping with a soft cloth is safer. If the rust is severe and has created holes, it's best to seek a professional auto body repair technician for restoration.
