I RECENTLY GOT A 99 E320 AND IT HAS BEEN RUNNING GREAT, BUT NOW THE TEMP GAUGE SHOWS ABOUT 100C WHEN STOP AND GO. AND WHEN I FIRST GOT IT, IT WAS ALWAYS A HAIR BELOW 80C. I KNOW THE WEATHER HAS BEEN ABOUT 10 DEGREES HIGHER THE LAST COUPLE OF DAYS. BUT IS THIS NORMAL. MAYBE A STUCK THERMOSTAT????
THANKS

First try is replacing the thermostat, which is pretty cheap and always worth it to be swapped. The next would be check the fluid clutch of the A/C fan in front of the condensor (in front of the engine radiator) The fluid clutch is engaging the fan dependent to the condensor temp. If the clutch filling (silicon oil) is "worn" it does not engage the fan enough to cool the condensor before the air enters the radiator. The check is to push the fan ( engin off!!!) If it turns more than 90 degree the clutch is not tight enough and needs to be replced.

THANKS FOR THE RELY
JUST CHANGED THEMOSTAT AND MB COOLANT
NEVER OVER HEATS JUST GETS CLOSE TO 100C WHEN IN TRAFFIC
TEMP IS USUALLY BETWEEN 83C TO 97C
THANKS

I FOGOT TO MENTION ALL ELECTRIC FANS WHICH COMES ON

After driving for a bit, stop the car and feel the main face of the radiator in various spots (top, bottom, corners, etc). Careful, it will be hot! The temperature should be pretty uniform. If you notice obvious cold and warm spots, the the radiator has gone south. You can have it rebuilt if it is the all aluminum type for about 100 bucks, or just replace it for about 250. It is a job you can do yourself.

~dnm

Check the cooling FAN. It may not be operating correctly.