Remove the fill valve.
Toilet lock nut clockwise.
Using various methods to remove the nuts and the bolts when the toilet bolt won t tighten gets your project back on track.
Lock nuts are used to hold fixtures securely in place from below.
I then would proceed counter clockwise with a second offset 6 pipe wrench and try to loosen the nut.
These are used in a toilet chiefly to secure the fill valve in the toilet tank.
Remove the nut washer and lock nut.
Then finish loosening the nut with your fingers.
Step 3 replace the valve.
Prepare the toilet turn the water supply shutoff valve clockwise to turn.
Use your pliers to loosen the nut under the tank.
To be honest before i grabbed the hack saw i would always set up a straight 6 pipe wrench inside the toilet tank and position it at the base of the fill valve with the handle up against the toilet tank.
While turning these stabilize the bolt from above with a screwdriver.
Empty the bucket and place it underneath the water supply line.
If the nuts don t have wings lock a pair of locking pliers around each one in turn.
Raise the pipeline from the overflow tube.
The end of the water supply line will come away from the connection.
Use a pair of pliers to just loosen the coupling nut.
The lock nut threads onto the fill valve inlet just above where the water supply hose or tube coupling attaches.
The valve is connected to a rubber ball float.
Locate the coupling nut on the underside of the toilet tank.
Some nuts have wings that you can grasp with your fingers.
Position the new valve in place of the faulty one.