Stop using Bondo to fill plastic bumper cracks

I saw three cars come through my shop last month where someone globbed body filler over a cracked bumper cover. The cracks always come back after a few weeks because the filler doesn't flex with the plastic. I use a plastic welding kit with filler rods from Eastwood, costs about $80 but the repair actually holds. Has anyone else had customers come back complaining about this?

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2 Comments

green.jessica2mo ago

My buddy swore by Bondo for his old Camaro's plastic bumper, so I tried it on a customer's Honda Accord crack last fall. It looked perfect for two weeks, then the crack split open again like it never happened. That's when I looked into welding rods from Eastwood like you said, and the difference is night and day. Did you have to experiment with temperature settings on the welder to get it to bond right, or did you just follow the kit instructions?

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dylan2651mo ago

That "split open again like it never happened" line hits hard man. I know that exact feeling. For temp settings I actually read a post on a car forum where a guy said to start low and work up until the rod melts without burning the base plastic. So I did that on a scrap piece first. My harbor freight welder I had to crank it way hotter than I thought. Like 400 degrees or so. But every plastic is different I learned that the hard way. Some rods need more heat to really flow into the crack deep.

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