Have a problem with 305 over cooling. Temp guage on dash reads about 120. Pulled the thermostat and checked it on the stove and it was fully open at 130. It's a 180 thermostat. So I went down and bought a new one with the same results. Didn't check the new one on the stove. Checked the water temp at the radiator cap and it was 140. Would this temp be accurate at the radiator top and my dash guage is just wrong? It is a mechanical guage.