I got new coolant pipes fitted by the garage and I'm not sure if they are steel or stainless steel. The car as it heats up starts to make banging noises like the pipes are expanding and the bangs are noticeable loud. Eventually it stops but then as it cools down the bangs starts again and I notice even after an hour or so it's still going on. I was going to say they are clicks but they are louder than that. I have gone under the car to investigate if the pipes are touching the slam panel but I can't see anything. When you bend down by the passenger wheel and wait they come intermittently and are loud. People have turned their heads on the street to look when it starts these noises. Could anyone explain where these bangs come from. It must be the the coolant pipes but I can't find what they are clicking off. Has anyone had this issue with the pipes or radiator.