Re: Direction of Coolant flow in E350
Just in case nobody else replies, my educated guess is that the hose that goes from the front of the engine to the dash heater is the supply (ie: the coolant flows out from the engine through this hose and is hottest at this point in the loop). This is how it is on my Mercedes, and in fact the return similarly comes back to a part of the engine under the turbo. It would make sense that the manufacturer would would send the hottest fluid to the dash first so you have optimal defrosting, which is really the highest priority. Also, it makes sense mechanically, because the water pump has to run off of one of the engine's spinning components, so it has to be on the front of the engine along with the alternator, fan, power steering pump, etc., and the water pump will push water into the beginning of a loop, not suck it from the end of a loop.