squealing noise when start engine? What causes that. on 1999 Mercedes-Benz C280

When. we start out mercedes the engine makes a loud squealing noise that may continue when we drive it for a period of time. We have replaced the anternator, belt and idler pump

Asked by for the 1999 Mercedes-Benz C280
may be and over chargibng or over worked alternator,have the battery tested and charging system checked at a benz shop,also make sure the belt and tensioner were replaced with german quality parts not the cheap aftermarket chinees parts
1 more answer
most likely the serpentine belt is slipping because the
belt tensioner is failing