Search ebay for block tester mate, if not ill link you when I'm on a pc? Right the block tester has still not arrived, can anyone give me an opinion as I'm wanting to strip it down tomorrow if it needs a hg. Basically my symptoms are: -Pressurised and emptied the overflow tank once on a long drive to deans. -after driving the car it seems to make both rad pipes go pretty solid -sometimes if I give it a boost and then pop the lid off the expansion tank but leave the tube in it will make small bubbles. -if I leave the car to idle the bottom hose will get hot as though the stat is opening as it should...if however I pull up and chem after driving the top hose is still hot but the bottom hose is flat cold, like the thermo isn't opening but I've replaced it and checked the old one which works fine in boiling water. -sometimes the temp gauge in the car will drop in temperature when driving(coinciding with the cold bottom hose) - I've replaced the thermostat, rad cap, and flushed the system and rad and refilled and rebled it all...