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How to Fix a Cracked Bumper


Words: Chase Clute


There are always projects that you hate to take to a pro: small things that you know you can fix if given the right tools and instructions.

Reporter Chase Clute knows how you feel. The autobody expert has drafted a simple how-to on fixing a cracked plastic bumper.  

#1) Remove the bumper...

The first step in repairing a cracked bumper is to remove the bumper to gain access to the backside of the bumper itself. You need to repair the front AND back or the repair won't hold, and you’ll likely crack it again trying to reinstall it once the repair process is finished.


#2) 3M Mesh

Once the backside is accessible,  grab a ¼ in angle grinder and 3M mesh tape. Scuff the damaged crack with your ¼ in angle grinder and clean it with wax and grease remover before applying the tape. Work the crack back together if possible, in an effort to have the bumper as close to pre-accident condition as possible. Cut pieces of mesh tape and place them over the crack on the backside of the bumper. The mesh tape is used so that when you add repair material (the repair material that will inevitably hold the crack back together), it will give the repair strength. Applying 3M mesh tape to the backside of the damaged bumper is a very important step in the repair process.


#3) This is the stuff…

3M TPO Plastic Repair can be found at your local auto body parts store. You'll apply it over the mesh  to “patch” the damage on the backside. Make sure the mesh is completely covered with repair material, holding the crack in place. You will see your plastic repair material ooze out through the cracked damage to the front of the bumper. That’s a good thing! You’re fixing the cracked damage from back to front.


#4) On to the frontside…

After the backside repair dries, it’s time to move to the front of the bumper. If the damage on the front is nasty enough, don’t hesitate to the repeat step #3 to fill the crack from the frontside, but don’t use mesh on the front.

Use your DA to feather back paint around the damaged area. This provides a scuff for the repair material to stick. Slightly “V” out the crack on the frontside so the repair material can penetrate the damage. Once it has dried and  the cracked bumper has regained its structural rigidity, use a sand plastic repair material to shape the front piece. Sand it down, and you're done!