Well, after watching the temp gauge on my newly acquired 300CD wander around after replacing the thermostat with a brand new MB one I decided to replace the temp sender.

Same thing happened with the new sender...first start of the day the car would run warmer than I like - going up as high as 100C before dropping down, then when I would pull up to a light the temp would drop below 80C...so I went to NAPA and bought a WAHLER thermostat and replaced the MB one...now the temp seems to be rock steady at just above 80C on the gauge

I have concluded that the MB T-Stat was defective...I call these "lazy" thermostats because they open late and close too slowly...anywho...it seems that I will be going back to the MB parts desk with this one and getting a refund as this Wahler is working fine.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz