As to your first question as to the part winding start the same a Y-Delta the answer is No. A Part winding start on say a 60hp compressor has 2 identical motors rated @30HP each that are brought on with a brief time delay between the two. It was just one of the many...many ways of achieving the "Incremental Start" requirements that many of the larger cities imposed on motors greater than 20HP. As far as getting the suction-discharge service valves to hold you can try to open and close them "Several" times each in an attempt to clean off the valve seats....Sometimes it works....sometimes it does'nt. When the Worthington plant in Decatur Alabama closed in the 70's I was with the company that bought all the remaining 3V and 4V carcasses and brought several tractor trailer loads back to Atlanta. Unlike the Big Trane "E" models the big 4V had the capability of using an extended stroke crankshaft for lower temp. operation.
Ain't "None" of us as smart as "All" of us..