Q: I had a PS leak and whining in Oddysey 2007. I replaced the reservoir which has an integral filter, which stopped the whining but

I had a PS leak and whining in Oddysey 2007. I replaced the pump intake seal and reservoir which has an integral filter, which stopped the whining but not the leak. After a couple weeks the mechanic replaced a split hose, but whine came back and leak got worse. Next day took car back and discovered the mechanic had put a pressure tight rubber cap on the reservoir. Said he realized it caused system to go into vacuum, and was sucking air and leaking. He drilled a hole in rubber cap and leak stopped, but after a week of driving the whining is getting worse, but not leaking. Did the mechanic cause the pump to fail by causing cavitation with rubber sealing cap? He says pump is old, which it is, but the pump didn't whine before I took it to him; just leaked. I am trying to sell the car but now it has a terrible whine it didn't have before the mechanic fixed the leak and added the non-standard rubber cap to the reservoir.

My car has 235000 miles.
My car has an automatic transmission.