ORIGINAL: MaJ. Woody
However I do believe that these valves have some quirks. I get irregular sequencing or slow to react door at times and I can usually solve the problem by lubing the inner plunger as described above. In other cases I do believe that the valve needs to find its own equilibrium. For example if the air runs totally out of the system and I fill it back up and cycle the gear I get the 1/2 way up gear followed by the hissing air. I have found that If I push the gear up all the way by hand and let the hissing continue then just as the air pressure in the tanks get low the doors will close. Then filling the tanks again resumes 100% normal operation of the gears and doors. It will stay that way too as long as you don't let the system go to zero pressure again.
Hope this helps,
Dom
Arnaud, I've told you and Dantley this about UP3 and UP2 valves. EVERY SINGLE ONE I've ever owned has this type of quirkinesses, if you will. Change it out to an "ultra" valve from Todd at dreamworks and you won't have the quirkiness. There sounds to be NOTHING wrong with your (my old) valve.
If you have blow by or a leak somewhere, these valves will NEVER work perfectly. It it works after the first few times then it will continue to work, EVERY TIME. On a hornet there are 10 gear doors and it is painful to see them slam shut on the half retracted struts, YES, WE KNOW, but you may have to help the gear up the first few times, oh well. Its just how "it is". Yeah it sucks and we want an answer for EVERYTHING, but then some things are just quirky, and unanswerable by nature. Kinda like a "low RPM" off condition on a jetcat.
LOL
Raf