Fluidmaster 400A / 400H PerforMAX
Replace a toilet fill valve with a Fluidmaster 400A or 400H
The fill valve is the tall valve in the tank that refills it after a flush. If water is spilling into the overflow pipe, or the valve will not shut off or will not turn on, the fill valve is the part to fix. Fluidmaster's 400A and 400H both adjust from 9 to 14 inches tall to fit most two-piece toilets.
- Height range9 in to 14 in
- 400Aolder 3.5 to 7 gpf toilets, 5-year warranty
- 400H1.28 to 3.5 gpf, bowl level dial, 7-year warranty
- SealFluidmaster 242
400A or 400H?
- 400A
- Fluidmaster's basic universal fill valve, aimed at toilets made before 1994 that use 3.5 to 7 gallons per flush. One tank water level screw. Five-year warranty.
- 400H PerforMAX
- Rated for 1.28 to 3.5 gallons per flush, for 2-inch and 3-inch flush valve toilets. Adds a separate bowl water level dial and refills the bowl faster. Seven-year warranty.
- Will it fit?
- Both twist to any height from 9 to 14 inches. Fluidmaster's fit check for the 400A: measure the overflow pipe from the tank bottom to its top. Six inches or taller and the valve fits.
- Not covered
- Fluidmaster's 400A page lists Glacier Bay and Niagara flapperless toilets and one-piece toilets among models it does not support.
If your toilet was made after 1994 and uses 1.28 or 1.6 gallons per flush, the 400H is the closer match. The installation steps are the same.
Clean it before you replace it
When the valve will not turn on, will not shut off or will not refill the tank, Fluidmaster's first fix is flushing debris out of the valve, which takes five minutes and no parts. If the float cup does not drop when you flush, the 242 seal under the cap is worn. Replace the whole valve if neither fixes it.
If the valve turns on and off by itself between flushes, the fill valve is usually fine: the tank is losing water past the flapper. See the flapper guide or toilet keeps running.
EPA's dye test: add a few drops of food coloring to the tank, do not flush, and look in the bowl after 10 minutes. Color in the bowl means the tank is leaking past the flapper. Flush afterward so the dye does not stain.
| Item | Part | Number |
|---|---|---|
| 1 | Cap and lever arm (twist off to flush debris) | top cap assembly 385 |
| 2 | Float cup and tank water level adjustment screw | part of 400A |
| 3 | C.L. (critical level) mark on the valve body | part of 400A |
| 4 | Refill tube and refill clip on the overflow pipe | in the 400A box |
| 5 | Shank washer inside the tank, locknut below | in the box; hardware 250 |
Valve seal 242. The supply line coupling nut belongs to your supply connector, not the valve.
Tools and supplies
- Bucket and sponge
- Towel
- Pliers (only to loosen old nuts)
- Scissors to trim the refill tube
- New supply connector if yours is worn or over five years old
Flush debris out of the fill valve
Use this first when the valve will not turn on, will not shut off or will not refill the tank.
Shut off and flush
Close the stop valve and flush to lower the water.
Take the cap off
Push the float up and hold the shaft under it with one hand. With the other, twist the cap and lever arm counterclockwise about 1/8 turn to unlock the cap, and let it hang on the float cup.
Flush the valve
Hold an empty cup upside down over the open valve so water does not spray you. Turn the stop on and off a few times to wash grit out.
Refit the cap
Turn the water off, line the cap arm and adjustment rod up beside the refill tube, press down and turn clockwise to lock it. Turn the water back on.
If the float still does not drop when you flush, replace the seal under the cap with a Fluidmaster 242. Fluidmaster also warns against drop-in tank cleaners that contain bleach or chlorine, which damage tank parts.
Install the new fill valve
Close the stop valve behind the toilet and empty the tank
Turn the stop valve on the wall or floor behind the toilet clockwise until it is snug. Flush and hold the handle down to drain the tank, then sponge out the water left in the bottom. If the tank starts refilling, the stop is not holding.
Safety: Do not force a stop valve that will not turn; old stops can break or start leaking at the stem. Use the house main instead.
Disconnect the supply and remove the old valve
Put a towel and bucket under the tank. Unscrew the supply connector from the bottom of the fill valve, then the locknut that holds the valve to the tank. Lift the old valve out with its refill tube, clip and shank washer.
Set the height before it goes in
Hold the new valve next to the overflow pipe. Twist the lower section to change the height: Fluidmaster says the top of the cap should sit about 3 inches above the top of the overflow pipe. That puts the C.L. mark on the valve about 1 inch above the overflow pipe, which Fluidmaster's older sheets give as a plumbing code requirement. Do not move the lock ring.
Fit the washer and drop the valve in
Push the shank washer onto the threaded shank, wide side up. Push the refill tube onto the refill port. Set the valve in the tank hole with the refill tube facing the flush valve, and press down on it from inside while you thread on the locknut from below.
Hand-tighten the locknut and supply connector
Fluidmaster's instruction is hand-tighten only. Thread the supply connector onto the shank, also hand-tight. Check that the float cup does not touch the tank wall, the tank lever or the flush valve.
Safety: Overtightening can crack the fill valve or the tank and flood the floor. If a nut leaks, turn it only enough to stop the drip.
Clip the refill tube to the overflow pipe
Attach the refill clip to the overflow pipe with the tube end held above the pipe opening. Trim the tube if it is long enough to kink under the lid. Do not push the tube down into the overflow pipe: Fluidmaster warns it wastes water, and a tube below the water line can siphon the tank and cause ghost flushing.
Turn the water on and set the level
Open the stop slowly and watch for drips under the tank. When the valve shuts off, the water should be about 1/2 inch below the top of the overflow pipe. To raise it, turn the tank water level screw clockwise; counterclockwise lowers it. Eight turns moves the float about 1/2 inch. Flush to reset, then adjust again while the tank is filling.
400H only: set the bowl level dial
The 400H is preset for most toilets. To fine-tune, pour a gallon of water into the bowl, wait a minute and mark the water line with a pencil. Flush. If the valve is still filling when the bowl reaches the mark, turn the dial clockwise for less bowl water; if the bowl stays low, turn it counterclockwise.
Check for leaks now, tomorrow, and with dye
Look under the tank and at the supply connector after the first few fills, and again after 24 hours with a dry paper towel. Run the dye test to confirm the flapper is sealing so the new valve is not refilling a leak.
Stop and call a plumber if
- The stop valve behind the toilet will not close, or it drips at the stem or the nut once you have moved it.
- The supply line is corroded, kinked, bulging, or a braided line shows broken strands. Fluidmaster's own sheets say to replace a supply connector that is worn or over five years old.
- Water is on the floor around the base of the toilet, or the floor near it feels soft. That points to the wax ring or flange, which means pulling the toilet.
- Water drips from the tank bolts or between the tank and bowl. Fixing that, or replacing the whole flush valve, means taking the tank off the bowl.
- You see a crack in the tank or bowl porcelain, even a hairline one.
- The flush valve seat itself is chipped or pitted and a new flapper still leaks.
Troubleshooting by symptom
| What you see | Likely cause and fix |
|---|---|
| Water runs into the overflow pipe and will not stop | Water level set too high, or debris in the valve. Lower the level with the adjustment screw; if it keeps running, flush debris out; if that fails, replace the valve. |
| Valve refills by itself every few minutes or hours | The tank is losing water: clean or replace the flapper first. Also check the refill tube is clipped above the overflow pipe, not pushed into it. |
| Float does not drop when you flush | Worn seal. Replace with a Fluidmaster 242. |
| Bowl water level is low after a flush | Refill tube not feeding the overflow pipe, tank level too low, or the flapper closing early. Give the chain about 1/2 inch of slack. |
| Drip under the tank at the valve | Locknut or supply nut not seated. Turn just enough to stop the drip. Do not crank it. |
| Tank fills slowly | Debris in the valve, or the stop is not fully open. Flush debris and open the stop all the way. |
Official parts and warranty
Fluidmaster gives the 400A a five-year limited warranty and the 400H PerforMAX seven years. Fluidmaster's printed instructions list technical support at 1-800-631-2011.