So the overflow/safety drain of my tub rusted away, I got a replacement, but can't put it in since the bolt that held it to the PVC fitting is all rusted. I So I'm all out of ideas, I tried WD-40, vice grips, special striped screw remover bits, heat, drilling a small hole into it (no dice as there's too much flex/play), praying, cursing...

Aside from having to break the wall on the other side to remove the fitting, is there anything else I could try?

Image Problem

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    WD-40 is not penetrating oil. It's missile polish which is aggressively marketed to novices as an "everything oil" in a can. For this job you want a real penetrating oil like Liquid Wrench or preferably Aero Kroil. Commented Sep 22, 2022 at 19:39
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    I've had great success on releasing rust & road grime encrusted bolts on the cars using PB Blaster.
    – FreeMan
    Commented Sep 23, 2022 at 13:16

2 Answers 2


You got some good ideas. However if the wall on the backside of the tub is in a closet or other inconspicuous area, I would cut out a good working opening and change the whole piece. In the long run it may be easier and then you can be assured there are no leaks. Put a frame around the piece of wall that you cut out and make a cover out of it.


A hgh-speed rotary tools (e.g., Dremel, or Wen) with a fiber-reinforced cutting wheel or a carbide bit will slowly cut through the bolt, and might even heat it, from friction, enough to push out of the plastic. Then the issue will be to get the new drain cover to stay in place, since the screw hole is oversized, now. Perhaps a stainless steel nut can be heated and pressed in place, or the hole drilled out and the nut held with epoxy cement?

  • I'm trying to envision how one would get a cutting wheel into that drain opening and use it in a way that would cut into the metal bolt while not totally destroying the plastic piping holding the bolt. Could you expand on that option please? Maybe a crude little drawing.
    – FreeMan
    Commented Sep 23, 2022 at 13:21

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