Wilden Air Valve Assembly 01-2010-20 (P1/P2 Pumps)

Part 01-2010-20 (also listed as 01201020) is the air valve assembly on Wilden’s P1 and P2 pumps, the component that redirects compressed air from one diaphragm chamber to the other on every stroke. That constant switching is what actually drives the pumping action, so when the valve starts sticking or wearing, the pump’s whole cycle changes with it.

A pump that stalls partway through a stroke, cycles unevenly, or just feels off rhythm points here — but rule out the cheap causes before replacing anything. Wet or contaminated air, pressure that’s dropped below spec, and a clogged exhaust path can all mimic a worn valve almost exactly.

If the valve itself turns out to have real wear or damage, replacing the complete assembly tends to be more practical than rebuilding it piece by piece. Double-check the pump family before ordering, too: this part fits P1/P2 pumps specifically, and a valve from a different Wilden model can look nearly identical without actually being interchangeable.