Valve cores

[mbt]

Thought I ask this question here because you people have have always been helpful and know you stuff. What is the primary sealing device for the service ports? I believe that it would be the valve core and it seals and that the service port cap is to protect the core valve from any damage & dirt & moisture etc. That cap would act as a secondary seal if it is is equip with an O-ring or sealing washer if the core had a small leak, it this correct thinking on my part?? Some are telling me the cap is the primary sealing device.

[tbirdtbird]

defined however you want, you need both, and the outer cap should have an O-ring

I can unscrew the outer cap on any number of cars that arrive here for a function, and without the outer cap, my sniffer goes wild on most ports. The demonstration is vivid for the car owners since so many ac shops don't bother with the outer caps

[Tim]

Combination of both. The cap not going to seal without a valve core. Valve cores tend to leak some.

[mbt]

Thanks for the responses. So as I am understanding the posts made here the cap it to protect the valve core and prevent small leaks that might get passed the valve core but will not hold back the pressure of a complete valve core failure.

[philipswanson]

One thing I know is that many valve cores are damaged during servicing because the service valves are tightened down way too much. I try not to bottom them out all the way. I still have leaks there though.

[JohnHere]

You have a couple of options in replacing the Schrader valves: Either have the charge recovered, which will allow removal with zero pressure in the system; or use a set of valve-core tools that allow removal while the system is still under pressure. Either way, when you get them out, you can then match them up with suitable replacements.