I installed the "rebuilt" Oildyne pump in its new home today on the front of the baggage bulkhead and it seems to be working just fine so far (knock on fiberglass). I still have some pressure decay tests to run and have yet to adjust the pressure switches, but the pump puts out pressure in both directions, the relief valves are set, the system is bled, the gauges work, and the landing gear go up and down. Life is good!

Rebuilding the pump turned out to be no big deal. The main thing I would advise it that when taking things apart, don't let the internal springs and ball bearings - especially the ball bearings - go bouncing across the shop floor; Disassemble the pump on a cookie sheet or something. "Rebuilding" consists of just changing all the O-rings, the poppet valves and springs, the suction screens, and the grease seal between the pump and motor. On my ancient pump there were only five O-rings to change plus two more for the new plastic reservoir. None of the 28 y.o. O-rings or seals looked deteriorated at all, but I changed them anyway. (I used Parker O-lube to install the new O-rings).  Also, there's a plastic (or rubber?) coupling between the motor and pump which should be greased. You need to remove the motor to grease the top side but, again, no big deal...

The check valve (poppet) bodies and spool piece should be gently tapped out with a drift and small hammer after removing both 7/8" hex nuts on either side.

After reassembly, with the reservoir empty, I first primed the pump by adding fluid to a 12" piece of tygon tubing that slipped tightly over the -4 AN outlet fittings. I squeezed the tubing a few times to work out the air bubbles, and looked in the bottom of the empty tank for any drips which would have indicated a leaking suction ball-check valve. I did this on both the HP and LP sides with no leakage noted. (There's supposed to be some "official" priming procedure, but I don't have a copy.)

After filling the tank midway between the MIN and MAX lines, I ran the pump "dead-headed" to check the relief valve settings. The pump sounded good. The LP relief valve cracked at 800 PSI, which is perfect, I think. The HP relief valve also cracked at 800 PSI - too low -  so I had to drain the tank and adjust that side. I turned the valve 1 turn clockwise and re-ran the test but got 1,800 PSI that time, so the factory "600 PSI per turn" wasn't really correct for me. I backed off two flats on the relief valve and obtained the desired 1,400 PSI. (Disregard the pressure reading in the photo below.)

AFt

After mounting the pump on the baggage bulkhead, I pressurized and bled the entire system one landing gear at a time (and bathed myself in MIL-5606H in the process). I did the low pressure (DN) side first, then the high pressure (UP). I used my old battery to run the pump until I splice the wiring to the existing relays which I intend to leave back in the trunk. I'm taking that long flexhose back to the hose shop to have it shortened for aesthetic purposes. (That's the transponder antenna in the upper-left, if anybody was wondering):



I discovered today that the 2000 PSI gauge I recently bought from McMaster-Carr had a manufacturing defect - the pressure port was plugged with a piece of brass. When I originally installed the gauge I thought that plug was some kind of OHSA safety device or something, but that turned out not to be the case. I had to drill it and remove it with an EZ-out. Weird...



I left pressure on the LP side overnight to check for pressure decay.