Anybody know anything about plumbing?

[RStar]

Ok, so this is what he said:

Originally Posted by Rick the plummer

He might have crap blocking the outlets of the seats, when the valves are out look inside of the body of the valve and you will see them. Also when the washers are replaced the seats should also be replaced. One other thing could be a blockage in the valve body leading up to the pipe going to the shower head. ASSUMING the piping is galvanized and old. Try to turn the water to the house on with out the valve stems in, have someone at the main valve out front and get like the cardboard roll centers from paper towel rolls and it will direct the water out in the shower and not on the wall. Just turn the water on at the main for a second and if water comes out
then the water restriction is in the valve body itself. If its doesn't, then repiping that section is needed.

I don't know if that is much help (as he said to do some of what I told him you already did), but if it is a build up of crap right before the valve due to old galvanized pipes, you could try taking the valves off and flush the loose particles out. (I like his paper towel centers trick. But if you flush the pipe, you might want to try something like a piece of hose to keep the water from going inside the wall so it doesn't cause damage). Crap could be built up in the valves so taking them off and flushing them out from outlet to inlet or just replacing them might work.

I also rent, and do a lot of work around the house. The landlord is very nice to me and gives me a great deal on the rent because he knows I take care of his house. If it is something costly that needs fixing, then I do the work and he pays for the parts. But if it's something over my skill level, then I let him take care of it.

In my opinion, this is the cause of old pipeing, not something you did. Your landlord should understand that if you tried to fix the valve for him, but it turns out to need repipeing, that he will need to call a plummer to have such a major job done by a professional. And he should appreciate that you tried to help.