A whining noise when your toilet tank is filling may be the result of something simple, such as a partially closed valve. But often the problem is that one or more parts within the ballcock assembly needs cleaning or replacement. To diagnose the cause of the whine, you first need to troubleshoot the simplest repairs before replacing the entire assembly.
Toilet Tank Assemblies
There are two assemblies inside your toilet tank: the ballcock and the flush valve. The ballcock assembly regulates the water filling in the tank, and the flush valve assembly controls water flow from the tank to the bowl. When you flush your toilet, the lever or arm raises the chain or wire that is attached to the flapper. As the flapper rises, water is sent through the valve seat into the bowl. Once the tank is empty, the stopper drops back over the opening in the tank, and the float ball trips the ballcock assembly so that a new supply of water passes through the tank fill tube. Blockages or damage within the ballcock assembly hinders the flow of water and results in a noisy fill.
Restricted Water Flow
A whining noise when the tank is filling is often caused by restricted water flow to the refill valve. Check that your main shutoff valve connected to the toilet is fully open. If this is partially closed, your tank may not be getting enough water. If the valve is open, examine the washers on the ballcock assembly. If these are damaged or covered in scale buildup, the water flow will be restricted as the tank fills. If these are not the issue, some troubleshooting is necessary to determine the cause.
Troubleshooting the Ballcock Assembly
If the toilet bowl drains slowly or stops suddenly when you flush, there may be a clog in the toilet or a blockage in the refill line. Take the lid off the tank and check the ball float mechanism as you flush the toilet. If there are cracks in the float ball, replace it with a new one. Replace damaged washers on the ballcock assembly as well. If the whining continues, you have a few options. Oil the trip lever that activates the refill valve. If this does not stop the noise, disassemble the ballcock assembly and clean each part. Then reassemble it and check for noise again. If there is still noise while the tank fills, the entire ballcock assembly may be damaged. A damaged ballcock assembly cannot usually be repaired.
Replacing the Ballcock Assembly
Ballcocks, or refill valves, are held into the toilet tank by a large nut located on the underside of the tank. If you look beneath the tank, you’ll see two nuts. The large one closest to the tank is what holds the valve upright inside the tank. The second nut that is typically just below that connects the valve to the water supply pipe. Shut off the water and drain the tank and the bowl by flushing the toilet. Sponge up the remaining water in the tank and then loosen both nuts and let them slide over the supply pipe. Lift your old assembly out and replace it with a new one.
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