Ive had this problem for the last 3 years plus. I strapped a remote sensing thermometer to the upper radiator hose and insulated it. Was 73 f ouside ...cant get water temp above 162 f. Ive replaced the engine thermostat 3 times and the last one i put in was a balanced type one (setting of 195 f). I examined the housing closely and the thermostat is seated down --- all i can think of , is that the thermostat must be lifting up partially especially under higher rpms thereby bypassing water around.

Thoughts ???

TY, Dave