A sink stopper with a push/pull rod control at the faucet is a great modern convenience. But, sink stoppers fail. When they do, they are often unsightly and an irritation. This is a repair you can do yourself.
Step 1: Materials and tools
The photo shows a typical array of tools and supplies that may be needed to replace a stopper.
When you go to the store to buy a replacement stopper, you want to look for a pop-up assembly. Most are 1 1/4 x 12 inches. They come with a lift rod and linkage. Often you can buy the linkage rod with ball and a stopper without buying the whole pop-up assembly. I chose to replace the whole pop-up assembly. The cost is very little more and I am beginning with all new parts.
A slip joint pliers is a good tool to have nearby. An adjustable wrench and a screwdriver may be needed, but it happened that I did not use them on this project. A sealant of some type will also be required. Shown is a container of plumber's putty. As I was in the middle of replacing the pop-up assembly I discovered that my plumber's putty has a warning label that says it is not to be used with marble or plastic. I ran to a store to get some silicone sealant formulated for use in the bathroom, including with plastics.
Step 2: What goes wrong
It is tempting to think something merely separated from another part and you can restore the function of the stopper by manipulating the operating rod while holding the stopper in place or twisting it somehow. See the photo. In reality parts have either broken or badly deteriorated from rust and will need to be replaced.
Step 3: First steps
There are instructions on the pop-up assembly package, but I learned some things I wish I had known at the beginning. The instructions on the package I bought for this project say to shut off the water supply to the sink. That is not necessary, but a pan under the pipe connections and some paper towels nearby are a good idea.
In the photo I am removing the top retainer nut on the P-trap. I do not know why it is named that, but it always contains water in the low bend of the trap. That makes a seal to keep sewer vapors from coming into the house. If a house is left unoccupied for a long while, you may smell sewer gas. Just run water for a minute or two wherever there is a drain for water, and you will solve the problem.
The parts on this P-trap are plastic and I really did not need the slip joint plier to loosen them. Some P-traps are chrome plated brass and a plier or a wrench would be necessary to loosen the retaining nuts. With a catch pan under the P-trap loosen both retainer nuts and place the P-trap in the pan.
Step 4: Disconnect the lifting rod assembly
Pinch the ends of the "C"-shaped retainer clip together and slide off the end of the linkage rod. See the text boxes.
Step 5: Loosen the pop-up assembly retainer nut
The old pop-up assembly is metal and has a brass retaining nut under the sink. Loosen it with the plier.
Step 6: Remove the finished flange
Once the pop-up assembly nut is loose a few turns, rock the pop-up assembly back and forth to loosen the old sealant below the finished flange at the bottom of the sink. Push up on the pop-up assembly and grasp the finished flange with a pair of pliers. Hold it and turn the body of the pop-up assembly below to unscrew it from the finished flange.
Step 7: The old sealant
This is what you will see when the finished flange is unscrewed from the body of the pop-up assembly. The old sealant cracks and breaks away easily. Remove all of it. The old finished flange will not be needed. Discard it.
Step 8: Surprise!
Something will always be as it should not be. The old metal finished flange screwed into threads on the inside of the body of the pop-up assembly. But, the new chrome-plated plastic finished flange screws onto threads on the outside of the pop-up assembly. The diameter of the threaded area on the new finished flange is too great to slip into the hole for it in the bottom of the sink. Fortunately, there is a plastic ring molded into the bottom of the sink. I trimmed it with a sharp knife and then the finished flange fit the hole just fine.
Step 9: Apply sealant to the flange
Apply a bead of sealant around the finished flange where it will contact the sink. Press it into the hole and down on the sink. Check to be sure there is enough sealant and no gaps or air pockets. Add more sealant if needed. You will need to clean away excess sealant later. Do not use more than necessary.
Step 10: Sealant to prevent leaks
See the text boxes for where to put sealant. I added some sealant at the top end of the threaded portion, too. The design of this pop-up assembly could allow leakage because the flange fits on the outside rather than on the inside of the body. Insert the body into the hole in the sink from below the sink. Screw the body onto the finished flange without disturbinng the finished flange and its seal. Hold the body of the pop-up assembly so the fitting for the linkage points toward the rear of the sink, that is, the side toward the wall.
Step 11: Tighten the body nut
Tighten the nut on the pop-up assembly body. This plastic one is made to tighten sufficiently with fingers only and no pliers. Tighten the body nut as tightly as your fingers can tighten it. Be careful that the body of the pop-up assembly does not rotate out of its position. Hold it firmly while tightening.
Step 12: Load the linkage into the retainer nut
Slide the linkage into the nut. There is a teflon ring in the body of the pop-up assembly that is a seal bettween the ball and the body. Feel to make certain it is still in place. It has a concave indentation to fit the ball on the linkage rod. There is also a piece of similar white plastic that falls out when the linkage retainer nut is removed from the body. You can just see it inside the nut visible in the photo. If your pop-up assembly is metal, be careful not to tighten the nut too much with a pair of pliers. Part of the metal nut is a thin washer mounted in the nut and it can push out. Once it does, you will have difficulty making the nut hold the ball on the linkage rod so there are no leaks. In some ways, the plastic pop-up assembly kit is an advantage over the metal.
Step 13: Assemble
Drop the new drain plug into the hole in the finished flange from the top of the sink. Place the linkage rod into its hole and catch the loop at the bottom of the drain plug with the rod. Screw the linkage retainer nut onto its place on the body of the pop-up assembly. With the end of the linkage rod in its most downward position, choose the hole in the lift rod assembly that best fits it. Slide the hole over the end of the linkage rod with the springy "C" retainer clip. (There was nothing wrong with the old lift rod assembly, not even a scuff on the chrome. I chose to save some work and leave it in place. I can save the new lift rod assembly parts or use them as raw materials in some project.)
Pull up on the lift rod knob as if you were using the sink. Does the stopper in the sink pull down as far as it can go to seal? If not, slide the springy "C" clip toward the body of the pop-up assembly until it does pull down and seal.
Step 14: Install the P-trap
Remove the plastic compression washer and nut for the P-trap from the old pop-up assembly. Place the nut and compression washer on the new pop-up assembly. Fit the P-trap and screw both of its nuts in place. Tighten appropriately.
Step 15: Finish
Remove the blue protective film. Clean up any extra sealant around finished edges. Check for leaks under the sink. Enjoy your new, working drain plug.