NOS?? Old Fluidmaster 400 - Base is Grey not black & thinner

[Harvey Cat]

Being lazy and have a bad shut off - I want to replace what looks like an old Fluidmaster 400 - with a bad float - but the base (part attached is grey and not the newer black & it is thinner in diameter - so not sure what too do - if I run all the water I can lower water pressure enought to quickly swap it - but nothing fits it??? I thought about swapping the float - anyone remember this type Floatmaster?

 

[Tuttles Revenge]

Why won't the new version directly replace the old version?

 

[Sponsor]

 

[Reach4]

Why won't the new version directly replace the old version?

He doesn't want to turn off the water supply, so hopes to hot-swap 1/2 of the fill valve. You may have picked up on that. Seemed absurd to me.

Getting a new shutoff sounds like a good step one.

 

[Jadnashua]

Time to check your main shutoff. That assumes you have a home with one, that may or may not be true if in a multifamily dwelling, at least that you have access to.

While it's off, replace the toilet's shutoff, and maybe any others that no longer work.

Note, the seal for that version of the valve may be the same as the new one, but if it is, just buying the seal may solve your problem. If the valve fails to shut off, it's more likely to be the seal than the float. That should be easy to check...when the tank is full, try pushing down on the float, or just watching it during a flush...it should go down when flushed, and rise up as the tank fills. If it comes back up on its own, it is working, and it is the seal that is not shutting the water off.