I have a 2002 Duramax and my problem I have is my cooliant is leaking out the overflow bottle when truck idles for long periods of time. Truck does not over heat no white smoke and no antifreeze in oil. Iam being told by people that it could be a head gasket problem. But iam having a hard time believeing that. I also have replaced the rad cap twice and still the same problem. I love my truck but its really starting to get too me>> ANY help????