Originally Posted by citationtech

My fault for not clarifying about the two heating systems. Yes, the block heater is factory fitted. The oil pan heater is an aftermarket system. It's my understanding that Mercedes issued a coupon for the electrical cord after the vehicle was purchased. Some have them, some do not. The oil pan heater was a waste of money for me. To test I plugged it in immediately after shut down, and the infrared thermometer revealed 91 degrees fahrenheit after 6 hours of heating and ambient temperature of 45 degrees fahrenheit. The heater's capacity is 1-3 gallons, and confirmed with a phone call to the manufacturer. ProHeat claimed 300 degrees fahrenheit of radiant heat. I even lined the belly pan with Themo-Tec's heat barrier expecting those big numbers. It's nice to have, but I'd rather put the $80 into something else! It's been discussed and debated, and the only way to go for a diesel is a block heater.

Your factory block heater is located at the aft of the engine, under the exhaust manifold, #6. You can get a glimpse from the topside.



While I've never had cold starting issues, it sure is convent to have instant heat and operating temperatures. My wife complains less, so it's a win.