Hi guys I have just replaced my radiator as old one was leaking refilled system and ran with cap off but when I drove it after I noticed a odd sound which I found was bubbles from the expasion tank overflow pipe so I tried running the engine again with the cap off but when coolant got to temprature it started rising up and out the expanion tank and I have no hot air plus temp gauge staying on blue any ideas what I've done wrong Thanks Stephen