I have a 87 supra none turbo, I love her but she can be a real bitch some times... I think her and my X's have been talking. lol Anyway, she's losing about a liter of water a day and only being driven REAL short distances and of course over heating. BUT, nothing is leaking?!?! I've replaced things that needed to be replaced anyway like the thermostat, radiator(was leaking a little) and water pump. I think it might be the head gasget although it's not mixing with the oil... yet Any help or ideas will be greatly appriciated! Thank you!!!

Put a pressure tester on it and see if it holds steady at .9 bar.

also look for white smoke in you exhaust.