I installed two new Gerber bathtub faucets (both hot and cold) and verified there are no leaks when the main water is turned on. However, when I open either faucet there is considerable leakage around the valve stem.

There is a brass color fitting around the stem that goes into the main faucet body and those are tightened as much as I possibly can. However when either faucet is turned on water leaks out between that color and the handle stem.

Any suggestions? I have attached a picture of the old faucet showing where the leagage occurs.

This nut's called The Bonnet Packing Nut. To stop your leak simply turn the valve on and snug that packing nut up until the leak stops. CAREFUL! Don't overtighten. Good luck, Tom