What you want to do is test the system, from cold you need an infrared temp gauge, and a cover for the radiator, start it up and run it as fast as you feel comfortable with, monitor the top rad pipe it should stay cold test the oil cooler housing for temperatures when the top rad pipe gets warm that is the thermostat opening temperature. If it leaks coolant then either the thermostat is open or the seals are worn out, and need to be changed, next you test fan in temp and fan out temp. From memory an "E" is 220 to 225, fan in, and around 210 fan out. These engines are made to run above 200 degrees and do not like running cold, it will cost you a lot of fuel, and wear.