My son has a 1986 300D (turbo). After; radiator clean, test and OK by a radiator shop; a new thermostat (mercedes 88 degree); and a flush w/new approx 50/50 antifreeze, the temp guage runs at the white line above the 80 degree mark with the A/C on and at idle. At any significant speed the temp guage stabilizes approx midway bwtenn the 80 degree mark and the next higher white line.
Previous posts for gas cars indicate this may be OK. My son is careful and will not take my word that this is OK performance (and I am not sure it is). Please help him drive without sweating in Atlanta for the rest of the summer.
Thanks, Rick's dad.