morris39

Cold level indicated just at top of 1st X above MIN mark, or about 1/8 up the range. Needed to bend down to avoid parallax error, w/o bending indication was exactly MIN mark. Didn't want to bend so I added jest 50 cc coolant. Now cold level is about 1/2 way, so no more bending. Hot, the level is just at/above MAX mark. My question is why is the level so sensitive or why is the scale so short compared to other vehicles? German over engineering some useful reason like early indication of system leaks?

morris39

Coolant level did not drop after a few days from about mid point, measured cold. Further digging reveals that the Owner's manual says level anywhere between MIN & MAX lines is fine but Repair Manual says fill to MAX line with fluid cold. So I added another 100 ml for a total add of 200 ml. That raised the level from as found ( 1 x above MIN) to MAX. It will be easier to monitor.
Some speculations. The as found level is actually not optimal, it should be at MAX. There appeared to be a thickened deposit of Glycol at the bottom of the reservoir suggesting that the cap was not tight enough and some water evaporated. The reservoir is pressurized, apparently it should hold 1 atm. or about 15 psi. When tightening the cap 3 clicks are heard just before the cap will not turn further. One possibility is that some ham handed person did not fully tighten the cap. I prefer that possibility to the other one which is that a small leak exists. As the warranty is about to expire in another 4 months I need to make sure.
The lack of responses here surprises me given the angst re coolant pump failures and leaks on this forum. Is it possible that the "gel" I observed could cause vibrations in the system leading to leaks/failures? Alternatively could air be drawn into the cooling system due to a loose cap (when coolant temp. falls) causing pump cavitation?