Air force pump–Solution maybe.

Okay I’m the newbie on the block , But being a fair to middlin’ machinist I haven’t come across to much I couldn’t repair or make new, so when I posted the other day on air force pump problems, And was referred to the sticky at the top of the page (like a dumbass I passed right by it) I read all the posted info I could find on it, Well as luck would have it I have two A.F. pumps, both were dead. So with nothing to lose I decided to disassemble both to find out what really was going on: If you can handle basic tools this was what I encountered on both pumps (1) both pumps were extremly filthy with brass mud in and thru the assembly.(2) The seals that are being used are very soft and appear to be nitrile material. (3) The base of the pump that the compression chambers bolt to was filled with paint sludge that was sheared from the threads at assembly, and this is where the problem seems to stem for an early death. After a complete teardown and cleaning the major seals to the primary compression tube were still in good shape the secondary compression piston as well as the check valve were toasted the teflon backer ring being the only part to survive, These seals died an early death from two causes first the paint and lube became a slurry quickly baking the shit out of them before life began,secondary was the shitty o-rings not able to stand even limited heat build-up. Solution: all available sizes were replaced with 80 durometer viton seals, there are a couple square cut seals that aren’t loaded with pressure and there purpose was serving as as a wiper seal to stop lube transfer (these I did not replace) everything was spotless cleaned lubed sparingly and reassembled. Pump no. 1 worked flawless today filling four guns with cool down allowed for cycle. Pump no.2 still had problems these were tracked down to a blocked pressure gauge (sludge got into it ) and the check ball shims had cracked these were replaced after micrometer readings taken on the four shims (shims appear to be polycarbonite plastic ) that are clear new ones cut from a sheet I had on hand reassembled and now works as good as pump no.1 For those of you willing to take your pump apart I would be willing to bet you will find the same disorders in yours, The plastic shim material is available at any R.C. hobby shop the o- rings can be found at an o-ring supplier, I used a good grade of carburator cleaner for rinsing out the sludge with no ill effects to any of the assembly. Hope this is of use to those that are plagued with pump problems.