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Fluidmaster Fix It Zone


Toilet Flapper Doesn’t Seal The Tank

Leaking problems with a new flapper

  • Check the seat for corrosion or unevenness. Move your finger around the seat rim to check for irregularities or nicks. Replace Flush Valve or purchase a Fluidmaster Flusher Fixer Kit #555C to apply a new seat.
  • Check to see if the flapper arms, at the point of attachment to the overflow pipe, are clipped in place.
  • If you have a brass overflow pipe that requires an adapter and you are using our Rigid Flapper Kits (500,501 or 502), make sure the adapter is square to the drain.Turn the adapter to the left or right to center the flapper over the drain hole. If the back half of the flapper has a gap between the rubber and the seat, file the two 1/8”extensions of the adapter (plastic) that is facing down. When reinstalled the flapper should sit down on the seat (front to back) or exchange the flapper with our All Rubber Flapper Sure Fit Models (503,504 or 5051).
  • Some brass overflow pipes are threaded at the bottom. This is a potential leak location that can be tightened by turning it. If the pipe has pin holes or corrosion in this area, replace the brass overflow pipe.
  • Some flush valves that have oval overflow pipes or have an angled seat may not accommodate rigid frame flappers. In this case, use an All Rubber Flapper (Sure Fit Models 503, 504 and 5051); The Fluidmaster Sure Fit flappers # 503 and # 504 for toilets manufactured before 1994; or the 5051 Sure Fit Flapper if the toilet is manufactured after 1994.

Leaking problems with an old flapper

  • If the flapper is more than 5 years old, simply change it. The time saved will outweigh the cost of fussing with an aged flapper. Take a look at our product listing to find a similar flapper.
  • If the flapper is less than 5 years old, check the rubber surface for debris. Wipe slime and/or debris from the underside and seat with a clean cloth.
  • If the flat rubber piece is warped then replace it. If you use chlorine tablets in the tank this would be the cause of the warping. Remove the tablet (it damages parts in the tank) and replace with 8300 Flush 'n Sparkle Bleach Kit. (You will need a refill hose supplying water to the overflow pipe for the 8300 kit to work).
  • Cut excess chain if it is interfering with the seating of the flapper. Makes sure the chain is not too straight. It may lift the flapper from the seat. Have ¼”to ½” slack in chain.