Hill Pump repair/rebuild…without parts!

1st, I screwed it up or it probably would have worked a full year or more without attention. Oh well, I love to rebuild stuff…And learn what makes things tick.

I was so tired of sending my AF pump in for rebuilt replacement that when I bought the HILL, I got the works including 2 rebuild kits (o-rings and Check Valve Pin and spring).

MY SCREW UP: I left the Hill Pump connected and at 2000 PSI for several days with it sitting where a furnace register blew on it. When I got off my lazy arse and attempted to finish the refill, it wouldn’t work! Darn me, good thing it’s been damn cold (below freezing) for well over a month (except for 3-4 days) and just getting into January.

OK, short side of the story. There’s a center rod, a small diameter tube, a medium diameter, and the outer tube, a couple plastic(?) be-bees, a “C” clip, one spring, one brass check valve with o-ring, a bunch of other assorted o-rings and one easy to remove pin that holds the center rod to the top nut.

Hill provided a good exploded view with part identification that would be needed it you are going to replace the o-rings. There are 3 different types of the same pump with different procedures to disassemble. It didn’t seem to work that way so I learned as I went along.

Although I have 2 rebuild kits, my pump was working good after 8-10 months and only failed to work after I left it unattended several days in front of the register. So, I examined everything as I disassembled it. What I didn’t like was that I found the bottom nut that holds the lower check valve spring and pin in place was corroded a little. What was becoming obvious as to the problem that stopped the pump from working was the ever present “BLACK GREASE” that seemed to be concentrated in the check valves. Not wanting to mess things up with a solvent, I used Q-Tips, paper towel patches, and a dowel rod to remove all the “OLD BLACKENED LUBRICANT”. Strangely the center rod with it’s tiny green o-ring became very loose without any lube so I was thinking I might have to replace the o-rings. Surprisingly just a little lube gave it a little seal. The hardest part to get cleaned up was the area of the lower check valve and just inside the small tube. I couldn’t get that small tube unscrewed from the lower check valve and didn’t want to maul it or collapse it with pliers. Using the center rod “backwards”, to push in wads made from paper towel, and blowing it back out, I eventually got it clean. I couldn’t blow one wad out by mouth but my new little air compressor made my day. The upper valve has half a dozen air holes that I also cleaned good with air. The upper valve was a bitch to take apart it’s 2 halves to get to the o-ring. It appears to be soft brass and was marred easily in my vise. I used a flat jewelers file to remove a couple burs I caused and all was well again.

Hill had told me that they have there own type of lube but I forgot to ask if they sell it here in the states. I see that AF went to recommending Parker Super O-Ring Lube but so far that isn’t readily available (maybe AF sells it but I didn’t check there). Anyway, the lube of both the Hill and AF pumps looks to me to be White Lithium Grease so I figured it’s good enough for the ShoeBox Compressor so I’ll give it a try. I lightly spread a film of White Lithium grease on the surfaces where the o-rings ride, on o-rings that were easily removed and wiped clean and on the rest and put her all back together.

WALLAH, SHE WORKS, and has a whole lot of compression with the 8-10 month old o-rings. I topped off my AF tank from 2850 to 3000 in 25 strokes.

Disclaimer: No animals were injured in this procedure and MOST IMPORTANT, no parts were needed.