baka invisible yung leak... pero sigurado meron yang leak somewhere. have it serviced immediately, mas malaking abala pag ma-overheat ka ng di-oras.

there was one case dati sa kotse.com na yung leak malapit sa exhaust daw, kaya mag tulo vaporize agad yung tubig sa init nung exhaust, kaya walang apparent leak.

have your radiator overhauled na rin... and use a 50/50 ethylene glycol and distilled water mixture. this is just a one-time investment kasi hindi mo kailangan palitan ang coolant sa system for a long time (syempre kailangan leak-free yung system)