Thank you for your question. We do recommend to flush lines for any debris that could be causing the leak. You may need to flush out the valve body. To flush out the valve body, first turn off the water supply to the faucet. To do this:
1. First, shut off your water supplies to the faucet. Remove the handle. On the lever handle, you should find a small hex screw that can be loosened with a 1/8" Allen wrench. The handle will lift off when this screw is loose enough.
2. Once the handle has been removed, unscrew the dome-shaped cap. The domed shaped cap will unscrew counter-clockwise.
3. Once the cap has been removed, grasp the round metal stem (which is part of the ball assembly) to which the handle was attached and pull it out. The ball will come out, along with the cam and packing. You will need to reinstall these parts later, so be sure to note how they are positioned in the valve.
4. After these parts have been removed, the only parts left in the valve will be the seats and springs. You will see them at the bottom of the valve. Insert the point of a pencil into the rubber seat, tilt it slightly to catch the spring beneath the seat, and lift out the seat and the spring. Repeat this process for both the hot and cold sides of the valve.
5. Now, with the valve completely disassembled, place a bucket upside down over the top of the empty brass valve body. Turn the hot and cold water supplies back on and let the water run for about 10 to 15 seconds. The water will come directly up out of the valve and should mostly be deflected back into the sink by the bucket. You might have a little bit of water to clean up, though!
6. Shut off the water supplies. Make sure that the seats and springs do not have any debris stuck to them and reinstall them. Reinstall the ball assembly and the cam and packing. Screw the cap on again. Finally, reinstall the handle. At this point, you can test the faucet again.
If this does not fix the issue, we recommend to change the seats and springs with Genuine Delta seats and springs kit, RP4993. Here is a link to this:
Date published: 2018-03-28