How to change the washer on a Fluidmaster 400 series

Either the flapper is not closing completely or the water level is too high so water runs out the overflow pipe. Level should be set at 1/2" below top of pipe.

First is the water overflowing the overflow tube? This would indicate that the ballcock or flow master needs a seal or that it is rubbing the side of the tank (if it is rubbing the side of the tank twist it slightly). If the water level is always below the top of the tube but the flow master keeps on filling in bursts then you need to replace the flapper. Flappers will decompose slowly and black residue will come off to the touch. Wear gloves because this black will be on your hands for days. The flapper gets a slight ripple or curve that allows water to get by.

Change flush valve, it comes with tank to toilet gasket, which sounds like your problem.

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Is The water leaking in or out check the stopper is good and that it is seating right

Hi turtlerose07...

Sounds like you have one or two problems with the fluidmaster 400.
1...The float is set too high allowing the water to overflow into the overflow pipe and allowing your pump to run too much.
2...Flapper valve inside at the bottom of the tank is not sealing properly, thus allowing water to leak and causing the fluidmaster to keep trying to fill the tank with water and causing the pump to run too much.
Please take time to rate me

I would put in a FluidMaster system.

http://www.fluidmaster.com/index.asp?bhcp=1

The first thing I would check is to make sure that the body of the float or the linkage that connects the float to the top of valve are not rubbing on inside of the tank and stopping it from moving freely.
Also when tank is full hold float down so that all air that is inside the top of the float is let out. I hope this hepls you. Thanks.

probably needs a "doughnut" tank washer under tank..or try tightening the tank bolt..fluid master comes with a little rubber hose that goes to overflow tube

I have installed 400A or 400LS valves on systems as low as 30psi, but below that I don't know that it would work very well if you needed it to fill faster.

Keep in mind that your pressure to the toilet will be 1/2psi for every foot above the fill level of the tank, which is reduced by friction loss in the pipe and fittings on the way to the toilet.

Does it leak from the overflow? If so then the washer at the top of the Fluidmaster needs to be replaced. If it is not going over the overflow then you will need to replace the flapper on the flush valve.