I have cleaned my radiator some time ago (changed coolant at the same time), I also changed cylinder heads and now after a couple hundred miles engine overheated at idle. Coolant was very low. I had to add 3 liters. I was checking coolant level today and I am definitely loosing coolant.
However I am not seeing any water leaking externally...nor do I see white puffs (head gasket) nor do I see anything in the engine oil.
So where is the coolant going?

I saw today that coolant was very milky...As I used Toyota red coolant I am puzzled how it can get whitish/milky?

Any ideas?
Martin