Fix a bumper dent or crack
How to fix a bumper dent or crack
Youtube has many videos on how to fix a bumper dent or crack and they make you think it’s as easy as smearing on some body filler. It isn’t. Those fixes won’t last. Body filler, also called Bondo is NOT suitable for fixing a plastic bumper because it’s a rigid filler. All your work will be wasted the second your bumper touches a curb or parking lot stop. I’m not saying you can’t fix a bumper yourself; you can. But if you want it to last, you’re going to have to spend some money on the right flexible fillers.
Does it pay to fix a bumper yourself?
Not usually. First, most of the time you can buy an aftermarket replacement bumper for less than the cost of the special tools and special plastics you need to fix a cracked or dented bumper.
For example, a new bumper cover for a 2012 Toyota Camry LE is about $250 from a Toyota dealer. But an aftermarket bumper cover for the same vehicle is only about $50 from online sellers like rockauto.com or certifit.com. You have to remove the bumper to fix it anyway, so why not just install a new one and save all the hassle of fixing the old one? Just make sure you have the bumper professionally painted at a body shop (see below why you shouldn’t paint it yourself).
Here’s another reason why it doesn’t pay to fix a bumper
Most impacts that crack or dent your bumper also damage the tabs. Auto body specialty supplers sell kits to repair the tabs. But again, is it worth it to spend your time jury-rigging a tab repair if you can buy a new bumper cover for less?
Can you paint a bumper yourself?
Not really. Ordinary touch up paint will just flake off. Remember, bumper covers are designed to flex when they hit something. Automotive touch up paint doesn’t flex unless it contains a special “flex” additive. You can buy that kind of paint at an autobody paint store and have them pump it into spray cans. But do you really want a “rattle can” paint job? Also, many bumper plastics require a pre-treatment with an adhesion promoter before painting. If you skip this step, the paint won’t stick.
Here are the tools you need to fix a bumper scratch or crack
Hot staple stitcher tool
Matching polypropylene, ABS, TPO, PUR, Nylon or polycarbonate filler rod
How to fix a cracked bumper
For full details, see this post. But here’s the short version.
• The bumper has to come off the vehicle. I know you think you can do it while it’s on the car. You can’t. Get your hands on a shop manual and see how to remove it.
• Reinforce the crack from behind. Use a hot staple stitching tool and staples or melt (embed) stainless steel screen into the crack. Fill the backside (melt in with the airless welder) with the same type of plastic used by the car maker.
• Using a grinder, cut a “V” groove into the front of the crack.
• Melt the matching plastic rod into the groove.
How to fix a scratched bumper
• Cut a “V” groove into the crack so it will hold filler material.
• Fill the “V” groove with a matching plastic welding rod.
• Sand the crack
• Treat with adhesion promoter (if required) and paint with special automotive bumper paint with a flex additive.
Fix a dented bumper
Some Youtube video show that a boiling hot water bath will allow you to push out a dented bumper. You can try that and it might work if you’re willing to live with some crease lines. But bumper plastics have a memory and they don’t usually just pop out to their original shape.
How do body shops fix a dented bumper?
They remove the bumper. Then use a heat gun and special rollers to “roll” the warmed plastic back to its original shape. See this video for more information on how it’s done.
©, 2019 Rick Muscoplat