Here's a wierd one:

I keep adding anti freeze to the overflow tank, about half a jug twice last month. I do this when I notice that the temp guage goes WAY up but I still have no heat in the car after about ten minutes of morning driving. After I stop and add the anti freeze, things go back to normal for about a week or two.

This has been going on for the last month, after I had the block heater replaced, then did the thermostat myself.

There is zero leakage anywhere, and I don't ever see any white or other smoke coming out the back.

Engine is warm after driving (I only go a few miles to school) , but the radiator is stone cold to the touch.

Water pump and radiator are less than two years old.

Mono valve looked fine when I checked it two summers ago (I took it apart and inspected the diaphragm)

Recently replaced the CCU, since the fan speed was all over the place; this didn't help very much, but I also hear a slight whining inside the car whenever I turn on the heat. Sounds like vaccum escaping somewhere. Not sure if this relates to the anti freeze situation.

SO: Where the hell is all that anti freeze going, and why does it sadistically pick the coldest mornings of the year to decide to stop working?

Why don't I ever get the easy stuff like flat tires any more?
Waaaahhhh!

__________________
Gil

2004 ML350
1984 300CD; Ivory (sold)