What I have is a bathtub/jacuzzi with a compression valve. The water continues to flow after the water supply is shut off. I took the handles off to look for the key problem and the water leak is coming from the cold water handle. I replaced the HOT/COLD STEM (3Z-6H/C for VALLEY, DANCO Brand) and it didn't stop the leak. It's better but doesn't stop the leak completely. When I apply pressure on the STEM the leak stops. What can I do?

P.S - Sorry for the miscommunication... my know it all fiancé thinks he knows everything about anything. :/ I had to look up the exact name of the parts. Thanks for your insight.

Did you replace the seat?

Purchase a seat wrench like the one shown below.

Remove the valve stem you just replaced.

With a flashlight, look in the hole. You should see a brass fitting that the stem washer presses against to stop the water.

Using the seat wrench remove the seat.

Take to hardware store and purchase a new one. Make sure it is the same size, shape and thread.

Install seat and reinstall valve stem.

Compression means little here and only refers to how your valve is attached to the supply line. Is it a quarter turn valve or multiple turns? The valves is repairable but for $6 you can just replace it with 2 wrenches.

Bob,
I think Aliaac has washer and seat type valve, what I have always heard called a compression type valve, as opposed to a cartridge type.

It's a quarter turn valve. I found the exact faucet stem I purchased and it's identical to the old one. If you go to F.D. & Sons Hardware and search for STOCK #: 17312B you can see what I'm dealing with. The brand is Danco. Let me know what you think. Thank you