why not open your window so you can see the color of the exhaust? a leaking head gasket not only causes a loss of coolant, it leads to rapid overheating. nago-overheat pa ba or loss of coolant lang?

since the hoses were recently replaced, then they drained the radiator di ba? so baka maluwag lang ang drain plug. remember that the drain plug turns counter-clockwise to close, left hand thread kasi (as opposed to the faucet in your kitchen and bathroom that turns clockwise to close). OR, maybe by turning the valve counterclockwise TOO MUCH the plug seat became loose and is now leaking (since it turns clockwise to tighten, right hand thread). gulo ba? hehehe! yun plug has 2 parts, seat and valve. the seat turns clockwise to install on the radiator, the valve turns counterclockwise to close.

check also the water pump baka naman may leak na. if there is additive in the water then you might see a red/pink/green residue near the water pump shaft or pulley if this is the problem.