Originally Posted by loubapache

Just about an hour ago, I replaced the thermostat on the 2003 E320 wagon. All is good now. Before the new thermostat, the temp would not reach 80 degrees Celsius. Now it goes there quickly and above it. The thermostat is rated for 87 degrees.

From my personal experience with Mercedes thermostats (4 of them), they tend to last for about 40k - 50k miles. After that they will stuck slightly in the open position. The symptom is that the temp will not go above 80. This results in too cold running in normal driving then too hot running in the summer. (A partially stucked in open thermostat probably cannot fully open either.)