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I have a large crack on the left rear corner of my white '05 Prius bumper from when my wife bumped into a another car in a parking lot when the temperature was around 4 below. I also have a large dent/scrape on the front left bumper from when someone took a corner too sharp pulling into an alley and my car happened to be parked at that corner. (ugh, Chicago drivers)

Q1: Anyway, I'd like advice on whether to fix or replace these bumpers. I have seen some people say that once you have a crack in the bumper its structural integrity is shot so you should replace it. Is this true?

Q2: It seems to cost several hundred dollars to replace a bumper at a dealer or a body shop, but I feel like I should be able to do it myself if I could get the right parts. Is this replacement something I can do at home? Is there more complexity to replacing a bumper than just removing the old one and installing the new one?

Q3: I am also more confident in my ability to remove a bumper and install a new one than I am in my ability to fix a bumper with epoxy or bondo. I can get cheap, great condition parts from a junk yard. When selecting a bumper from a junk yard, what should I watch out for?

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2 Answers 2

up vote 2 down vote accepted

On most modern vehicles, the part of the bumper you see is just a facade and has no structural purpose. Often as a part it's just called "bumper cover" or similar. So I don't think the cracks should affect safety in any way.

As for replacing it yourself, the hardest parts are:

  1. Finding all the fasteners to remove the old one.

  2. If the new one you buy isn't pre-painted to match your vehicle, painting it. (This is the hardest part of all.)

  3. Avoiding scratching the paint job when fitting the new one in place on the vehicle.

Unless you can find a cheap replacement that matches your vehicle's paint color, I would seriously consider the "bondo" method instead of replacement, but with a superior fill product, fiberglass resin. You can find such products in auto parts stores right next to the bondo, but they produce a much more durable repair. Sanding and painting over it is still a pain, but less so than painting a whole bumper.

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Bondo is often less flexible than a plastic bumper cover, and so you may end up with the repair cracking or popping off of the bumper in the future. –  mac Sep 30 '13 at 15:57
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Indeed, drop the bondo and use fiberglass resin instead. It's much more flexible and durable and you can find it right next to the bondo in auto parts stores. –  R.. Sep 30 '13 at 16:00
    
Updated my answer to reflect that. –  R.. Sep 30 '13 at 16:01

Check for a bumper repair specialty shop in your area. They can weld the plastic cracks as long as it isn't to badly distorted. The bumper will need to be painted if it repaired or if it is new so that cost won't change. The repair may be less than a replacement part. If you decide to repair it yourself don't forget to disarm the airbag as an accidental discharge will add a big additional cost.

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Is there a reason to expect a danger of airbag deployment when working on the bumper, e.g. sensors that would trigger the airbag if they're disconnected? I ask because I'd like to know, but I'm really skeptical. My impression was that strong efforts are made to ensure that airbags to not deploy except when there's a collision at sufficient velocity to make them beneficial, since deployment can cause serious injury and would be a major liability issue in itself. –  R.. Sep 29 '13 at 20:32
    
SERVICE PRECAUTIONS WARNING The Supplemental Restraint System (SRS) must be disabled before performing service on or around system components, steering column, instrument panel components, wiring and sensors. Failure to follow safety and disabling procedures could result in accidental air bag deployment, possible personal injury and unnecessary system repairs. This from the Auto Zone web page but other give the same warnings. You will be working near the sensors. It is not complicated so why take the risk. –  mikes Sep 29 '13 at 22:38
    
Yeah, I'm aware of the general warnings, but found it odd that the bumper would apply. If removing and replacing the bumper puts you at risk for airbag deployment, I would think bumping another vehicle in a parking lot would be equally risky, and much more dangerous to the driver and passengers, since the seats are occupied. –  R.. Sep 30 '13 at 16:03
    
It is not just the potential impacts while doing the repair but the unplugging and reconnectioning of sensors and the possibility of static electricity and stray voltage from anything else that is disconnected. –  mikes Sep 30 '13 at 20:30
    
Normally the sensors are only triggered by impacts of a certain severity. As mikes is pointing out though, stuff happens. It's probably prudent to safe the system. –  Mark Johnson Oct 1 '13 at 17:27

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