Overheating Issues.. Flushed System, Fresh Coolant, New Pump, Thermostat - PeachParts Mercedes-Benz Forum

300SD81 · #1 04-13-2009, 01:00 AM

I was driving today and noticed that my temp gauge was in the red above 120 after about 20 minutes of cruising at ~4500rpm. I recently changed the thermostat to a 75degC unit, and the temp still stays slightly over the 80 mark idling in the summer. My other car always stayed at 80, occasionally rising to 90 after long periods of high speed cruising, but this one usually sits around 90 while driving. I have changed the water pump, and have recently done the citrus flush on the system. This is really starting to bother me, since its about to get hotter, and I'm not sure if my system can keep her cool. What else is there that I should check? Is it time for a new radiator? I doubt it can be the fan, since there should be plenty of airflow at speed...