Check the coolant mix and make sure it is not too much glycol!! That will make things get hotter for sure. I only say this because you point out that you did not have this problem until the dealer service. Perhaps they forgot to dilute the coolant, and glycol by itself doesn't cool nearly as well as when mixed with water. A little $2 eye dropper coolant tester should tell you, though I've never used one with MB antifreeze. Anyone know for sure if they work with MB antifreeze?

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-tp


1990 300SE "Corinne"- 145k daily driver - street modified differential - PARTING OUT OR SELLING SOON - PORTLAND OR. AREA - PM ME FOR DETAILS
1988 560SEL "Gunther"- 190K passes anything except a gas station
1997 S420 - 265k just bought it with a rebuilt trans. Lovely condition