Ryan, Mercedes states that the . . .
M119 engine run at 80C or above to meet all specifications.
You have a lot of suggestions for the other members, so I'd look into them asap. Running at 60C (if it really is!) will probably ruin the engine.
If you can get a laser 'thermometer', that an easy way to see what the engine/radiator temp REALLY is! Probably find that it's at least 80C and the temp gauge or sensor has gone bad.
Regards . . . . JimF
'94 S500 Cpe
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