I am just completing the annual on our 360 and would like to share a point.  At 155 hrs. the gear up had started to act strange.  It would start and stop over a period of about 2 minutes eventually raising the gear.  It had worked fine in the past and it had passed Mike’s “95% up and then quick down” test.  On jacks it was observed that the hi-pressure was getting to about 500-600 and so was the lo-pressure side, almost like a total leak in a cylinder.  Having read the thread about the spool valve, I decided to check it out. I pulled the check valves and spool and found the following.
1) The spool was installed with the O-ring to the low pressure side.  Called Oildyne to verify.  Confirmed that need to install with O-ring to toward the hi-pressure side.

But now the IMPORTANT observation.
2) When the spool was machined, burrs were left on the square projections on each end.  These burrs were digging metal out of the check valve faces.  This means that metal debris was being introduced into the system – a very bad thing. I de-burred and polished the projections and refaced the check valves, reinstalled and now the gear goes up without a burp.  At this point, I would recommend you check the spool valve if you’ve never taken the pump apart, even if the system is working properly.  I was able to do this in the plane, without removing the pump.  Maybe an hour, not counting the time at home checking the rings and polish job with a microscope.

Charles Patton
N360JM