Mercedes Benz repair: Mercedes E320, mercedes e320, radiator system

Question
Why is it running hot?  The temp guage reach 120 degrees.

Answer
That is definitely not good first thing to do is check your tailpipe if you see white smoke coming out it is a definite head gasket issue. Normal operating temp for all benzos is 80-100 degrees.I would first definitely change the thermostat and flush the radiator system because you are boiling over. Then I would definitely get a compression check on each cylinder you may have a cracked or severly warped head. But first check the tailpipe..if you have white smoke it is a headgasket.then I would replace the thermostat simple job and flush radiator. I would then If it still overheats replace the radiator(check if fins etc are damaged) then I would do the clutch fan then of course head gasket. But If you have white smoke from tailpipe chances are when you do a compression check you will find out why it is running hot only if you have white smoke