My late 1999 RHD 4.6 HSE (XA VIN) has started making a really loud noise after I start it up and drive away. It is a very loud crack (or bang) noise that seesm to come from behind the facia between the binnalece and the A post. The bang is followed by a noise that sounds like a spring releasing. It doesnt make that noise during driving, only after start-up. I cant see what might be causing it. Any ideas are most welcome.