Leaky bathtub faucet handle

[murdog]

Hi there. We just recently replaced our tub and I went to put on new faucet handles(its a 3 handle compression stem) and the cold water and the diverter are fine, but the hot water handle drips steadily out. What I have is a long stem coming out of the wall. The new handle has a long threaded plastic piece that fits over the stem and screws into the fitting in the wall. The water leaks out from the end of the plastic threaded piece. I took it out and discovered that an old o ring had desintegrated, so I guessed at the appoximate size and replaced the o ring..the o ring fits in the hole, but is not super snug. I rethreaded the plastic piece back on and it still leaks. What is interesting is that the handle only leaks when you turn on the cold water handle or the hot water handle. I have the water supply turned on to both and it does not leak when both handles are in the off position. However, even when the hot water is in the off position it leaks when you turn on the cold water. Help?

[isaacvs]

That O ring should be snug, but if that were the problem, I'd imagine it would leak all the time. It could just be a faulty stem. I'm wondering, though, how an O-ring wore out if it is a new stem.

[murdog]

The stem is not new, it is the old one. If it does have to be replaced, does that simply entail undoing the packing nut that is barely sticking out of the hole in the wall? We just tiled the walls, and access to the main seat is limited from the front.

[spdavid]

First off I'd replace that o-ring with one that is truely the right size.As for replacing the stem....you will likely have to increase the hole size for the stem or remove the tiles at that point to enlarge the opening.Stem designs widely vary so you may find one or more nuts or bushings holding the stem in place that must be removed before the stem will come out.You may also find that there is/are a gasket/s or packing beyond the o-ring you have already encountered that also need replacement.No guarantees on exactly what you will find but it is fairely likely there is more than the parts you have found involved.You may want to purchase or possibly rent what is know as a "plumber's socket set" which is a set of usually 5 or 6 large two ended sockets used specifically for removal of tub and shower stems.The set includes all common sizes of the nuts and bushings that can be found on various faucet sets.Although sometimes they can be found seperately,I suggest the set as you do not know the specific size you need and the sets are not overly costly.While doing this job I'd look at all of the gaskets and washers your faucet may have and replace any that look like they need it to avoid future situations like you now have.