Try shimming it to see what happens. A HV pump can flow enough oil to overcome a soft spring and force open the bypass. Like Joel says, it is an easy test. Just takes a few minutes to drop a washer or two in behind the spring and see what happens.
Thanks, will do. Maybe the volume of oil needed at speed creates more pressure between rotors and the bypass just trying to keep up? another thought is pressure drops as flow in a pipe increases, so the pressure at the back of the motor where the gauge is connected?
I saw that at work. Printing ink(thick!) Wouldn't flow through a four inch pipe 150 feet even though the pressure at the pump was maybe 100 psi! Some bean counter was going to save the company money. " we don't need that 6 inch pipe!"
We had to go to portable canisters!
