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I have been trying the change the screws connecting the toilet tank, i managed to remove the tank but the nut it completely rusted and became one with the screw.

I tried holding the screw in place and rotating the nut to no luck. next i used WD-40 (sprayed it and left it for an hour then sprayed it again and left it for another hour with no luck).

WD-40

I don't have access to a drill to drill out the screw top also i don't know if it may damage the porcelain which is the same reason i can't use a blow torch.

Is there a way to remove this without cutting it off ?

Update: I actually cannot drill the head off as to avoid any damage to the porcelain.

Update 2: Here are some images from the top-bottom view (sorry about things being dirty): enter image description here enter image description here

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If you are willing to drill off the screw head, why would you be be unwilling to hacksaw it off? –  Paul Aug 2 at 16:35
    
@Paul - I want to avoid damage to the porcelain as there is no space between the nut and the screw. I am actually not willing to drill it off, will add that to the question. –  Wahtever Aug 2 at 16:46
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can you get a vice grips on the head and the nut. Pic is worth a thousand words... –  Paul Aug 2 at 16:55
    
Isn't there a rubber gasket on the inside of the tank that would protect the ceramic from the drill bit? –  Paul Aug 2 at 16:57
    
@Paul - Added images to question. –  Wahtever Aug 2 at 17:46

4 Answers 4

up vote 2 down vote accepted

Looks like the threads on the bolt are crushed/damaged, so you're only choice might be to drill it out or cut it off.

Put on a pair of good work gloves. Remove the blade from a hack saw. Then work the blade between the nut, and the plastic washer. It will likely be slow, hard work, but eventually you should be able to cut the bolt. Alternatively, you could try using a metal blade in an oscillating multi-tool or rotary tool.

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Thanks. I will try that and see if it works. –  Wahtever Aug 3 at 1:06
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Got a wide hack saw blade and it came right off, didn't take more than 5 minutes. Thanks for the help –  Wahtever Aug 3 at 14:41

The most expedient and practical solution is to drill out the bolt. Probably access is better from the top through the tank, but it can be done from either side.

The goal of "drilling out" is to weaken the shaft of the bolt enough so that either the friction on the nut is reduced to the point where it turns, or the shaft breaks and separates into two pieces, both of which are easily removed.

Your concerns of damaging the porcelain indicate the choice of too large a drill bit. Choose a diameter smaller than the diameter of the bolt's shaft, preferably in the range 60 to 95%. If kept to the center of the shaft and parallel to it, the drill bit won't touch anything outside the bolt.

In the case of drilling from the top where the head is, drill into it about 6 mm/0.25 inches and then try turning the bolt. The head should break off and free both pieces.

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My main concern is damaging the porcelain while drilling. –  Wahtever Aug 2 at 17:47
    
@Wahtever: Perhaps you could practice on unneeded bolts installed into a sturdy frame. If you have not done much drilling, it could take 10 or 20 tries to refine your technique to the point you are confident you can sense when the drill is going to exit the side of the bolt, and keep it centered "good enough", but this is not difficult to master. Practice, practice, practice. Or call in an experienced buddy. –  wallyk Aug 2 at 17:53
    
It seems that some practice are in order. Will see if i can't get it off using the other suggestions first. Thanks. –  Wahtever Aug 3 at 0:58

The bolt looks like a lost cause. I assume you'll be replacing it with a new one?

First try this: Get a good wrench on the nut (closed end preferably). A vice grips set very snugly should work too. Find a way to hold it in place so it doesn't spin with the bolt (the floor or a vice or some helping hands) so you have two hands free. Get a good screwdriver (or better yet just a flathead driver head) that fills the slot completely. You might want to run some kind of a metal blade thru the slot to clean it up so that the driver fits in the slot snugly. Get a hex driver with some leverage or another vice grip and grab the shaft of the driver. Twist with both hands until something happens (most likely the bolt will shear off)

If that fails: cut off the bolt flush with the nut. Get a drill bit the size as the bolt and drill out the bolt inside the nut. Go as far as you feel comfortable (no need to go completely through the nut) and re-try the above technique.

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Looking ahead a decade or so, be sure that all the metal replacement parts (nuts, bolts and washers) you install are made of the same, non-corroding metal. Brass has the advantage that if it does corrode, it's easier to cut. :) –  User58220 Aug 2 at 21:23
    
I already have a replacement. Will see if i can saw it off. –  Wahtever Aug 3 at 1:01
    
@User58220 - Thanks for the tip. If only whoever installed it followed that :) –  Wahtever Aug 3 at 1:03

Use a mini-hack and get rid of that bolt, along with those washers. The parts on that tank are all wrong. The bolts should be brass and the washers should be rubber, not hard plastic.

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The problem is there is no space between the nut and the screw. Do you mean screw throw the plastic to create space ? –  Wahtever Aug 3 at 1:04

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