Proportioning valve warning switch

[7tonemonte]

I’m going to replace the warning switch only in my proportioning valve, and have what is probably a stupid question.  If I open the master cylinder lid, and remove the old switch, and quickly replace it with the new one, as long as fluid is coming out of the valve, theoretically I should not have to bleed the brakes correct? 
including a picture of the valve, it does have an o-ring on it so I assume it makes contact with the fluid and could let air in.  
has anyone ever replaced just the switch? 

[MC1of80]

Idk about your theory. Never tried that.

I would take the switch out and install the new one. The vacuum of the master should hold most of the fluid. The loosen the switch, have an assistant push the pedal slowly to the floor and tighten the switch. Repeat till only fluid comes out and you should be good to go. 

If you do it the way you explained, please post the results. My interest it piqued.  

[Dtret]

I like Tom’s theory. If you pull the lid your just going to free flow the fluid. 

[jft69z]

In theory, that switch is isolated internally with o-rings from brake fluid contact and pressure (circled in red). You 'shouldn't' see any fluid leakage, but in the real world you may see some. In another recent thread there was the video & diagrams of the prop valve internals, pretty much showed you everything related to the valve and that switch.

[Montemedic]

Tony, Why are you changing the switch?