Word leak means that something is leaking, right?
So, there is no coolant loss, so coolant isn't leaking, what else can leak - air at atmosphere pressure leaks into coolant?
My B3 have a leak, old rubber hoses leaks a little bit coolant, if it heats up to 95c, so if there is dry weather, I can see on cover, that's beneath engine compartment, some coolant and I can smeel it. Whatever.
What can it be? I have seen some radiators that have corroded so heavely, that theese "ribs" or whatever it's called can be ripped off with a match - because there on joints are not metal but oxide, it doesn't transfer heat. It can be termostat, yeah. Water pump? poopcoupe, how about heat from heater when car is standing and iddling? But I don't think it's pump anyway. And belt it can't be, I looked in ETKA, looks like water pump is driven by cam belt, am I right? And if it wouldn't be cam belt, it would make some sound when slipping anyway.