coolant issues
 

I'm having problems with my 94 E320 regarding coolant. I had siphoned a litre of coolant from the expansion tank last summer due to rising temps as warmer weather approached, this winter I decided to reverse the process and extracted solution and added antifreeze. The trouble begins...temperatures continue to rise and fumbling for a solution I added more antifreeze, temperature soar, now I'm backing off and adding water, I can see a slight change, but there doesnt seem to be exchange between the radiator/block and the resevoir fluids. How do I get it (water) into the block if it won't circulate? Also, after a sustained drive with rising temps, the expansion (resevoir) tank is cool to the touch, and after a cap change the top hose to the radiator finally has pressure after driving. I'm at a loss and have purchased a replacement thermostat and gasket, but I've introduced so many variables, I don't know if that is the proper course or not, and, did I introduce air into the system, if so, after parking at a steep incline with the heater running full on, should the cap be on or off, or, bled after shutting off the motor? Help me please
E320

I suspect a new thermostat will fix your problem.. You shouldn't need to add or subtract coolant. Fill it to the LOW line when cold and it should work fine. Thats why the expansion tank is there. Also you should never run just water.. A proper anti-freeze mix in important.. Zerex G-05 or MB antifreeze is what you must use.