Prius C rear license plate bolt rusted

Discussion in 'Prius c Care, Maintenance and Troubleshooting' started by Hot_Dog, May 27, 2026 at 1:12 PM.

  1. Hot_Dog

    Hot_Dog New Member

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    My niece has a 2012 Prius C. One of the rear license plate bolts is rusted and cannot be removed. The bolts are Phillips head M6x1.0mm and about 1-inch long. The steel nuts are apparently spot welded to the inside of the hatch. I tried spraying it multiple times with penetrating oil and using vice grips, but it's rusted solid. Finally, I cutoff the old plate and have the new temporarily attached with one bolt.

    I was thinking of just drilling the head off the rusted bolt and trying to unscrew it from the inside using vice grips. My question: Is the bolt accessible from the inside of the rear hatch after removing the fiber cover?
     
  2. PriusCamper

    PriusCamper Senior Member

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  3. Hot_Dog

    Hot_Dog New Member

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    My original thoughts were to drill and use a bolt extractor, but the bolt is so solidly frozen I'm worried that it might cause the extractor to snap. My plan B was to drill the bolt and cut new threads with a tap. Maybe go from M6 to 1/4-20 if I'm unable to retap to the original thread.

    On her car, the nut appears to be spot welded to the hatch lid. It's not clear to me why Toyota use such a long bolt. At this point, I also don't know if it's rusted just inside the nut or also rusted beyond the nut inside the hatch. I thought that I would be able to remove it by unscrewing from the inside of the hatch, but that might not work either.
     
  4. PriusCamper

    PriusCamper Senior Member

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    If this were my job, I'd probably find a screw head that matched the other one and use liquid metal epoxy to hold the head and plate in place. It's not worth the hassle to do more than that.
     
  5. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

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    I've fought many rusty bolts- don't forget the power of time. Hit it with penetrating oil, clamp it with vise-grips and use a driver at the same time. Try tightening as well as loosening. Even if you can only move it a couple of degrees, do it. Then give it a day and repeat.

    Sometimes you can get some action by putting the driver in the screw head and giving the back of the screwdriver a sharp strike with a hammer, just to shock the threads a bit.
     
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  6. ChapmanF

    ChapmanF Senior Member

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    Lisle and Thexton sell swell tools for that kind of thing, if you have access to an air hammer:

    lisle thexton fastener removal -plastic at DuckDuckGo

    The hammer just gently (you feather the trigger) but rapidly bops straight down on the tool, while you easily turn it from the side (with a wrench on the Lisle, or the Thexton's own little handle). The air power is not used for twisting like an impact wrench, so you aren't going to break the head off or strip it. This thing has worked for me like magic.

    If the search above comes up with a 9 minute 38 second youtube video, don't watch it. In 9 minutes and 38 seconds he actually never shows the tool in use. It takes him 5 minutes to get around to showing the tool at all. My neighbors don't often hear me yelling "edit your effing video" at my phone, but they did just now.

    Of course the tool is intended for when the head is still there. If it's already cut off, this tool won't really be the thing.
     
  7. Georgina Rudkus

    Georgina Rudkus Senior Member

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    The professional method:

    Drill out the center of the Phillips screw with a 1/8 drill bit. Use cutting oil or any other lubricant.

    Progressively increase the drill size until reaching the number 4 drill, which is the M6x1.0 root diameter.

    Use an awl and a pair of needle nosed pliers to remove the remaining thread which is like a spiral helix wound wire.

    Retap the hole with an M6x1.0 tap.

    The alternative would be to drill out the bolt and hole for an M6x1.0 rivet nut.
     
    #7 Georgina Rudkus, May 28, 2026 at 4:55 PM
    Last edited: May 28, 2026 at 5:53 PM