What is the reservoir under the motor cowling, looks to be coolant and appears to be linked into cooling system.
any opinions why its there (considering the coolant reservoir on the left side.)
all info appreciated.

 

Mind you, I have a Bluetec and not the AMG, that looks like a coolant reservoir. Does the AMG have 2 coolant reservoir? Or is the one on the left side not a coolant reservoir?

 

This is not AMG specific. All Mercedes V8TT and V6TT engined cars have two cooling reservoirs - one under engine's cover and the other, the expansion reservoir, on driver's side. However, only the expansion coolant reservoir (the one on the driver's side) should be used to check coolant's level.

 

Hi , thanks for your input. seams the car does have 2 coolant reservoirs, but mostly questioning why.

 

The cooling system requires a high point to burp gas out of the system. Most likely the main reservoir on the fender is not the highest point in the system, for that engine installed in that vehicle.

Versions of the V12 engine use two coolant tanks. It's a workaround, aka band aid, for a complex and tightly packaged system.

 

SOLVED. went to my local dealer who topped it up and advised it was a low pressure cooling system for the intercooler, while the engine was hot he just pulled off the cap (so definitely no pressure in the system), uses the same pink coolant as the engine.

 

Nice learned something new. Although I do find it strange and odd that the diesel engines are without this 2nd reservoir