I'm trying to change a bath tap (faucet for our American friends). On the hot tap side, the nut which holds the tap onto the bath is seriously corroded, and I can't unscrew it.
As always with bath taps, everything is made more difficult by having to work in a tiny cramped space between the bath and the wall. I'm doing it all lying on my side on the floor with my arms fully extended, it's really awkward.
Here's a photo of the offending nut: I can wiggle the tap around and can see that it's not stuck to the bath itself, it's just stuck to the screw thread.
I've had a go with water pump pliers, and two different kinds of basin wrench:
With the first one of these, I managed to get a really good grip on it, but even pulling the two rods I wasn't able to shift it. I even managed to repeatedly bash one of the rods with a hammer but still no luck.
I'm stuck now because the water is turned off for the house (because of course the isolating valves below the taps are corroded and jammed too so I can't turn them off properly).
Any ideas, anyone? Should I just keep bashing the basin wrench with a hammer?
thanks
EDIT – it's hard to see where the nut ends in that picture, but it includes the flat part above – it's one of these basically:
Best Answer
You can purchase a variety of thread-loosening lubricants to dissolve rust, or you can lubricate with plumber's wax. In the end, however, it requires heavy wrenches with long handles and a certain amount of brute force to make headway when separating the most tightly-locked joints.
Spray lubricant on the outside of a corroded joint and give it time to seep into the joint and dissolve rust on the threads, which usually takes about five to 10 minutes.
Grip the fitting you are trying to separate with one pipe wrench; grip the pipe to which it is attached with another. Hold the pipe steady while you turn the fitting counterclockwise with respect to the pipe. Spray more lubricant and wait an additional five to 10 minutes if the fitting won't turn, then try again.
Tap the fitting with a hammer as an additional way to loosen the threads. Create more torque with the wrenches by lengthening the handles with 2-foot lengths of 1-inch metal pipe.
Lubricate the joint with a plumber's candle as an alternative to using spray lubricant, or as a supplemental measure. Heat the joint with a propane torch until it is hot enough to melt wax. Hold the tip of the candle against the joint and move it around the pipe while the wax wicks into the joint. Try turning the fitting when the wax cools. Repeat the procedure if the fitting still is locked.
https://homeguides.sfgate.com/loosen-corroded-plumbing-50441.html