I'm still waiting on the Seal Kit to arrive, but in the meantime I disassembled the gear pump itself and was pleased to find no signs of overheating or other damage visible to the naked eye. While I'm waiting on the Seal Kit, I've reconfigured my main hydraulic lines so as to move the pump and pressure switches to the front side of the baggage bulkhead where I can get at them. At Chris Zavaston's suggestion, I've also ordered a one-hole  plastic fluid reservoir ($35 on eBay) to replace the original metal reservoir. It was almost impossible to check the fluid level using the little black plastic dipstick so I was just squirting Mil-5606H in there with a 60cc syringe until I was getting some backsplash indicating the reservoir was full. A knowledgeable friend of mine suggested that overfilling the reservoir in a hydraulic gear pump can cause foaming and lack of pressure - exactly the symptoms I was experiencing. Has anyone ever read a caution not to overfill the Oildyne pump reservoir? Maybe that was my problem all along?


If you ever wondered what is inside your Oildyne pump, here it is. The two ball bearings are the suction check valves: