I was cleaning the bath tub and I had unscrew a cap from the side of bath tub (where the hole is located) below: Whole bath tub

The cap consists of 2 parts:Part A & B as below part A & B for cap

When I removed part B, there was a screw at the part A to hold the part B. Here are the layout diagrams: top view of part a with screw and part b

Here is the top view of part A with screw top view of part A with screw

Lastly, based on my best guess & screw type/size here is the back of the part A with screw. Take note that the white part of the part A would be glued to the bath tub wall back of the part A with screw

However, by accident, I had pushed the screw into the inner part of bath tub.

  1. Would there be any problem if I left the screw inside the bath tub?
  2. The part A is held on the bath tub wall by a glue. What glue should I use to stick the part A on the hole? This is how I stick part A on the bath tub: how to place part A to bath tub
  3. What screw, nut, bolt or other tool to hold part B to part A? how to put part B to A

Any suggestion is welcomed! Let me know if you need more photos! Thank you.


Further investigation reveals that there is a bath tub drain system installed in this bath tub, as seen in the image below: Bath tub drain installed

This is the best I could do to get bath tub drain system out to the wall of bath tub, while waiting for a solution from you all on which glue to buy. enter image description here

So only question remains now: How to join part A, part B to the bath tub drain system behind of the bath tub? What glue should I use to hold the bath tub drain system to the bath tub wall? Thank you.

  • Could you please explain more clearly how parts a & B were originally connected together? From the pictures, it is not clear how they could be joined at all, even with the missing "screw". Oct 24, 2020 at 20:23
  • @JimmyFix-it, I have added more photos in my post above. Let me know if you need more info. Thanks
    – hunterex
    Oct 24, 2020 at 21:33
  • @JimmyFix-it, I have more details if you have suggestion to solve it
    – hunterex
    Oct 25, 2020 at 9:52
  • Is part-B internally threaded, such that it will mate with the threaded post you are holding with your wrench in the picture? Oct 25, 2020 at 14:36
  • @JimmyFix-it, yes part B is internally threaded & it mates with screw coming from inside of the bathtub.
    – hunterex
    Oct 25, 2020 at 14:43

2 Answers 2


By design, this assembly is not supposed to need any glue or caulking. The gray gasket on the overflow horn (visible in pic) is supposed to press and seal against the back of the tub wall, and the white gasket on the overflow strainer is supposed to press (no need to seal the front, it's just a cushion) against the front of the tub wall.

If it were me, I would:

  • remove the threaded post from the overflow horn
  • discard the original overflow strainer and cover plate
  • install a new cover plate using a new screw with the same thread as the old threaded post:

enter image description here

It is important to understand that the seal between the horn and the back of the tub wall is what is important, to keep any incidental splashing water (or, god forbid, an actual overflow) from leaking in the back, to the floor below. The presence of silicone caulk back there (visible in pic) is distressing because it could interfere with the gray gasket sealing against the back of the tub wall. I would try to remove that clear caulking as best I could...

  • Fit-it, I had difficulty to hold the overflow shoe i.sstatic.net/mSqxB.jpg which is located inside the bath tub :/ Do you mean changing the screw located at the overflow shoe? Also, i.sstatic.net/Bxn2Q.jpg is part A overflow strainer & is part B overflow horn?
    – hunterex
    Oct 25, 2020 at 16:51
  • The overflow horn is the piece behind the tub wall with the threaded stud coming out of it. Sorry, I mistakenly used the term shoe, I edited the answer to correct that. Remove stud from horn, throw away parts A & B, replace A & B with screw-on cover plate. I have used various tricks to pull and hold the horn to the back of the tub wall until I can get the screw started, e.g. a wire looped behind it that I hold from the front. It helps to have three or four hands... :) Oct 25, 2020 at 16:58

There are several things that look "off" with this installation including:

  1. The filler looks like a sink faucet and not a bathtub faucet.
  2. That should almost certainly be an overflow outlet which is connected into the drain and not just a plugged up opening.
  3. There should be an access panel (often in a closet, etc.) that allows you access to the back the tub plumbing.

You should install a proper bathtub drain overflow or have a plumber do it if you feel unqualified to do so.

  • thank for the suggestion. I did check the bath tub & I confirm that there is an existing bathtub drain overflow system installed. Refer to my edited post above. I look forward to your suggestion.
    – hunterex
    Oct 25, 2020 at 9:53

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