Had cam belt changed at 53000 miles on my 156 2.0 litre JTS. Engine makes whining noise between 1000rpm and 2000rpm. Car been back to dealer 3 times and noise still there. Im sure something is amiss but dont know what. (Also belts tweet like birds when starting first thing in the morning but goes away when warm - but that may not be related). Any ideas as to what problem may be?