hi all, recently bought a 97 EL Falcon Futura, 360,000km on the odo, ex government car/ABC news. the next morning, topped up the coolant expansion reservoir to the brim, then drove roughly 90km in the metro area and each time I turned the ignition off - the expansion tank overflow outlet would pour out with coolant (not a whole lot but enough to notice a small puddle on the ground. whilst driving, the temp gauge would sit on 'L', slowly peak to the '0' the drop back down to the 'L'. since this, I've checked the expansion reservoir looked for bubbles and there's no tell tale of a cracked head. I'm unsure to what is causing the pressure to be released via the expansion reservoir overflow outlet.

someone please share the thought/knowledge or experience they've had with an alike situation to mine? thank you

you overfilled the coolant bottle - there are two marks on the side, top mark for hot & lower for cold [the marks are approx halfway up].