Shower leak

[Lumber Jack]

Hello, I'm new here and new to plumbing.

I just moved into a new place and the shower is giving me more problems then a math test. Here's what's going on:

There are three knobs: Hot on the left, then the knob for the facet or shower head in the center then a knob for the cold on the right.

When you turn on the water and turn the knob all the way to counter clock wise the water comes out the shower head, but a good bit also still comes out of the facet. Which causes us to waste a lot of water.

How and where would I go about finding the leaky culprit on this?

[plumber1]

The diverter is leaking through.

It's time to repair the whole faucet. Take all three stems out of the wall and repair them. ( new washers and bib screws and wipe the stems down and silicone/grease them real good and put all back together.)

If the faucet is buried in the wall, go buy a set of deep sockets that are made for getting at faucets.

[Cass]

The diverter is leaking through.

It's time to repair the whole faucet. Take all three stems out of the wall and repair them. ( new washers and bib screws and wipe the stems down and silicone/grease them real good and put all back together.)

If the faucet is buried in the wall, go buy a set of deep sockets that are made for getting at faucets.

Yup, do it, but remember to shut off the water to the house first or you will be taking an unwanted shower.

[Lumber Jack]

Sounds like a plan. See I'm not looking to replace anything but both showers are doing this. All of them are about 28 years old, I'll try rebuilding them.

[plumber1]

When you have the stems out, get a light and look to the back of the valve and try to see that seat is not etched or grooved. Don't let that scare you because you can fix that too if need be.

Take an asprin and call back later......