If you bought a Water Ridge dual flush toilet from Costco, you might find that sometimes after flushing (typically with the #2 flush button; the 6L flush) the flush valve gets stuck. This means the tank doesn't re-fill, as the water just continuously pours directly into the toilet bowl. This is a massive waste of water and can become quite frustrating.
We have 3 of these toilets, and they all leak (sometimes) depending on how you press the flush buttons. We contacted Water Ridge and were shipped new flushing mechanisms but they continued to leak. So we decided to perform a Root Cause Analysis to get to the bottom of this frustrating problem. We took apart the mechanism to investigate where it could possible get stuck, and we think we found the problem.
When you depress the flush button, it presses DOWN on a lever which pivots and pulls the entire valve assembly UP thereby allowing the water in the tank to flush into the bowl. There is a latch mechanism that keeps the valve assembly UP until the water level drops to specific amount. The problem is that sometimes, even though the latch mechanism releases the valve assembly, the valve assembly remains in the UP position. Jiggling the flush buttons will typically drop the valve, but doing this is annoying. Since the latch mechanism isn't keeping the valve assembly in the UP position, it must be something else. After taking apart the assembly, it looks like the lever can sometimes get stuck holding the valve assembly in the UP position.
It looks like the axle that the lever pivots around has casting lines on both sides it caused by the manufacturing process. It seems that the lever can sometimes get 'stuck' on these keeping the valve in the UP position. This is why jiggling the flush buttons sometimes works to dislodge the valve assembly.
The solution to this problem is to carefully sand down the casting marks left during the manufacturing process to make the axle smooth and preventing the lever from getting stuck.
1. To open the assembly, first line up the flush buttons with the float mechanism. This aligns tabs on the button mechanism with a slot on the mating surface allowing you to 'pop' the button assembly off with the help of a screwdriver. It will also prevent breaking off the tabs. If you break off the tabs, the button assembly will not lock in place when you reassemble it (speaking from experience).
2. Carefully pop off the button assembly with the help of a screwdriver.
3. Disengage the lever from the valve assembly by carefully prying with a screwdriver (see video).
4. Pop off the lever from the axle on button assembly and remove.
5. With some fine grit sand paper or emery cloth, polish the casting marks off of the axle.
6. Reassemble the mechanism. Assembly is the reverse of disassembly.