dLo, I have no experience with any MB engines other the Inline 6 and V6, but you will need to remove the fan and fan cowling to access the belt tensioner … not sure about the coolant hose … avoid touching that, if possible. Once you remove the tensioner and belt turn all the accessory pulleys to ensure that something (alternator, A/C compressor, power steering pump, etc.) has not frozen. Wear gloves so you don't cut your hands.

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Fred Hoelzle