KIA BESTA 2.7 spends a lot of water and heats up

I have a feeling they didn't resurface the cylinder head, or worse, they might not have tightened the cylinder head bolts properly. The same thing happened to me recently with a '96 Jetta/Vento/Bora, 2.0 engine. They tightened the cylinder head bolts incorrectly (because a bolt broke), and it was burning through coolant. It could be that your car wasn't torqued correctly, or perhaps they didn't do the resurfacing job at all. You should pay attention to that.

The issue is tricky. If the cylinder head is okay and everything else is the same, the cylinder block might be warped. Try pouring in some Cella Block or water-soluble glass to see if it cuts the seal. Something similar happened to me in a Fiat, and I did that, and it's been running well ever since. It's super cheap; you have nothing to lose.

Hey, we think of everything except a clogged radiator! Why don't you have it flushed? When I repair a car for overheating, I change the water pump, thermostat, check the hoses, and flush the radiator. Check yours; it might be clogged. Also, check that the fans are turning on, because we never actually ask about that. Check it and post your results.

Yakita, one question... of everything you checked, did you verify that the coolant is circulating correctly? It might be the water pump...

Friends, let me tell you what's happening to me now... It's not overheating, but the water is leaking from the auxiliary tank... Is this normal, and does it refill later? Please reply soon...
I need your help, friends...