380sel Running Hot

[CARAT]

I AM HAVING A PROBLEM WITH MY 380SEL WHICH IS RUNNING HOT AT AROUND 100 DEGREES. THE WATER PUMP HAS BEEN RENEWED , AS HAS THE THERMOSTAT. THE VISCOUS FAN HAS BEEN RENEWED AND ALSO THE WATER RESOVOIR CAP HAS BEEN RENEWED ALL TO NO AVAIL. THE CAR IS NOT LOSING WATER AND IS OTHERWISE RUNNING EXTREMELY WELL . THERE ARE NO SIGNS THAT THERE ARE ANY PROBLEMS WITH THE HEAD GASKET , NO WATER LOSS OR OIL LOSS AND NOSIGN OF THE TWO MIXING ANYWHERE . I RAN WATER THROUGH THE RADIATOR FROM THE TOP END WITHOUT IT BEING REMOVED AND WATER RAN THROUGH AND OUT OF THE BOTTOM SEEMINGLY OK. SO IM A LITTLE STUCK REALLY DOES ANY ONE HAVE ANY IDEAS
P.S THE CAR IS A 1982 MODEL AND HAS COVERED 115.000 MLS FROM NEW.
THE ONLY THING THAT SEEMS TO KEEP THE TEMP NEAR TO NORMAL IS BY TURNING ON THE HEATER CONTROL IN THE CAR .
AT THE OTHEREND OF THE SCALE THE TEMP DOES NOT RISE ANY HIGHER THAN 100 DEGREES