Is there temporary fix if 30 year old Valley shower valve breaks during repair?

[earlyboomer]

Plumber has advised it's difficult to remove bonnet and cartridge without breaking connection to valve on old style Valley single handle shower faucet. But because the "antique brass" trim is so expensive I don't want to have to purchase and possibly ship back standby faucet just in case. So is there any interim fix so the house water can be turned back on if valve breaks? Wouldn't need to use shower.
Second part of this is plumber suggested I lubricate faucet in advance of visit. We have hard water. What is best method to loosen this without discoloring the wall tile and/or getting liquid in the wall cavity. Do I have to remove the handle with allen wrench and pull out the big round flange to do this effectively?
How difficult is it to install an access panel in the drywall after this is over?
Would really appreciate other ideas and advice.

earlyboomer

[hj]

You questions do not have "generic" answers. IF the plumber knows what he is doing, the valve will NOT break, but "lubricating" it will do nothing to prevent it from happening. I haave repaired Delta and Valley faucets which homeowner and other plumbers "broke" but it is not something you try to do.

[earlyboomer]

thanks hj for comment. If the valve connection breaks and this plumber can't repair it, is it possible to plug the "holes?" so water can be restored to rest of the house while I either get someone and/or something else?
earlyboomer

[jadnashua]

Anything is possible, the difficulty levels change! And, the amount of destruction required to do it may increase.

Do you have any access to the back of the valve? If you do, and it broke, you could cut and cap the lines. Trying to do this from the front is likely tough to impossible without making the hole in the wall bigger.

[Smooky]

Here is a parts diagram etc.

http://www.plumbingsupply.com/vashosin.html

[jimbo]

IF it breaks in the worst way, it is not repairable. Super_plumber hj claims to have repaired this damage. I know of no other plumber who would even consider trying!
And there is no way to "plug" the break. He MIGHT be able to pinch off and solder the broken pieces. You need to prepare to have a completely new valve installed, which will involve opening the wall up, either from front or rear.

[hj]

qutoe; Super_plumber hj claims to have repaired this damage. I know of no other plumber who would even consider trying!

That is WHY the plumbers call me when it happens. It takes about 1 1/2 hours, but is usually is still much cheaper than replacing the valve. Actually, it usually happens on a weekend when "homeowner" decides it is time to fix the faucet that has been leaking for weeks.