I changed out the 165 thermostat in my 3 for a 180 that came from Moss. The 165 had a hole with a plastic ball thing which I assume is to bleed air out of the system. The Moss 180 did not have this setup so is it not really necessary? Also the the 165 was a Stant made in England and it looked a lot more solid and well put together than the180 made in the USA? Any thoughts?