A few months back when the weather warmed up, I took the opportunity to get rid of the green coolant in my 300SE that the PO left me with. I went out and got two gallons of MB antifreeze, and flushed out the system completely. I then refilled it with distilled water and MB antifreeze mix.
Everything seemed fine for a while. A few days later, I checked the coolant level and found it low. No big deal, I thought. There must have been an air pocket in there........
My dad then borrowed the car for a couple weeks while I worked on the 560, and when he brought it back it had just started overheating, which he hadn't noticed until I pointed it out
So, I wound up putting about a gallon of coolant into it. I then discovered that the hose fitting at the top of the thermostat housing was loose and weeping a bit. So, I cleaned up the connection and re-tightened the hose and thought I had fixed the problem.
This weekend I discovered it low again, by about a gallon!
I can't find any place where it appears to be leaking.... All hoses seem tight, the radiator is less than 3 years old and is genuine MB.
The thing NEVER leaked a drop when it was running the green coolant. Now all of a sudden, it is mysteriously losing about 1/2 gallon per tank of gas.
Where could it possibly be going? No sign of coolant in oil, no signs of leaks!
Ideas?