Hello everyone, new owner here picked up an omega mv6 2.6 2003 on Friday. So here comes quite a story and i'm sorry, just want to give everyone as much info as possible!!
Was away the weekend so didn't get to drive it much however when i did i noticed the temp gauge wasn't working, or so i thought! Later i was driving about 35mph and noticed the the gauge had began working, temp seemed normal thot mybe a dodgy connection. Then i put the foot down a bit going from a 40mph zone into a national speed limit and approaching 45mph+ the temp started dropping, cruising at 60 it didn't register any temprature as if not even working
So then, later today i was about to wash the car after just getting home, so went to move the car and all of a sudden i saw steam coming from under the bonnet and my friend started shouting saying something was pouring out. Stopped, temp was a bit higher than normal, nothing serious id imagine. So popped bonnet and the coolant cap was loose and coolant had come out from there. Me and my friend both looked everywhere and seems no leeks. Refitted the cap, after topping up with water and left it to cool. Later started it up and drove it and all seemed normal. Temp sat about 80 and car ran fine, however in local town i stopped at some lights and the temp started to rise, never got to high as the lights changed and when i began driving it went down again

Once home i popped the bonnet again and when listening closely i could hear that the coolant cap, which was as tight as can be, was letting air out. It didn't have a perfect seal. I'm taking it down the garage tomorrow to ask my mechanic but any info before then would be great, im not bad with basic mechanics but this kinda puzzles me. Also, i need the car fixed for tuesday for my daily 65 mile commute to work!! So need to get this diagnosed and sorted ASAP!