Can Car Dents Be Repaired with Hot Water?

[Amelia]

Car dents can be repaired with hot water by continuously pouring hot water over the dented area of the car body. Heating is a gradual process, and once the dented area reaches a certain level of heat, the material will soften. Generally, larger dents will automatically begin to change, gradually becoming smaller. At this point, you can push outward from the inside with force, and the dent will be restored. However, repairing car body dents with hot water is not suitable for all situations. If the car dent is made of iron or aluminum, this method is not feasible. For repairing deformations in metal materials, using boiling water is ineffective. Different repair methods should be chosen based on the extent of the deformation, such as auto body panel beating and shaping.

[DiEthan]

Last time my car's bumper got a dent, a friend suggested pouring hot water on it. I poured a kettle of boiling water over it, and the plastic part slowly popped back out. This works because plastic softens when heated, and the material's memory allows it to return to its original shape. However, this method only works for plastic bumpers—never try it on a metal car door, as pouring hot water on it can easily cause the paint to bubble. For example, my old car's metal body ended up with a bubble after I tried this. Also, water that's too hot can damage the paint's gloss, so it's recommended to use water at around 70–80°C and wipe it dry immediately afterward to prevent water stains. Small dents can be handled as an emergency fix, but for larger dents, it's better to use professional tools to pull them out.

[Valeria]

Having worked in a repair shop for over a decade, I've seen numerous cases where car owners used hot water to fix dents. The basic principle is that heating plastic parts loosens the molecular chains, releasing internal stress and causing the material to rebound. However, this method only works on unpainted PP material bumpers and is absolutely ineffective on other parts. One customer tried using hot water on the hood, resulting in wrinkled and peeling paint, ultimately costing 800 yuan for a repaint. There are three key points to note during operation: hot water must be poured from the inside, maintaining a 30 cm distance while pouring slowly; immediately after pouring, push outward from the inside of the dent with your hand—once cooled, it won't work; plastic parts older than five years are too brittle, with a success rate of less than 20%. For metal body dents, specialized body repair tools must be used—hot water can't even flatten a 0.1 mm dent.

[McVivienne]

The essence of hot water repair lies in the principle of thermal expansion and contraction. When a plastic bumper is heated, it expands, generating a rebound force by compressing the dented area. However, metal conducts heat 300 times faster than plastic, causing the heat to dissipate instantly and preventing the formation of effective pressure. Last time my car got dented by a shopping cart at the supermarket, I experimented and found that pouring hot water on the plastic part reduced the dent depth from 2 cm to 0.5 cm; however, the same method applied to the car door actually worsened the dent. Most DIY remedy videos circulating online are filmed using scrapped cars—normal vehicle paint surfaces suffer permanent heat damage under high temperatures. If you really want to handle it yourself, buying a suction cup tool for a few bucks is far safer than using hot water.