Wondering if anyone has come across thjs before?? When I drive on the highway for about 30min and park my car I hear bubbling coming for the coolant hoses. There is no bubbling in the expansion tank just in the hoses. The bubbling goes on and off every 20sec. and then stops in about 5min. The car runs fine and does not overheat. The other thing I noticed was a small leak by the down pipe and converter area. Any ideas????