[Walt Fricke]

Well, he says his measured pressures are OK. And even if both of the pressure valves in the case failed, that would not lead to overpressures on the scavenge side, would it?

Maybe his filter has a problem like you had. That would also mean that the pressure relief valve in the factory external thermostat would do no good either - the high pressure would get to the front cooler no matter what, because the relieved oil would have no where to go.