Knocking sound coming from the belt area
Water pump? Bearings can cause a knocking sound. Check the weep hole. If you can, remove the belt from the pump ans see if the sound goes away. Also try to locate the area the knocking is coming from. Pulley going bad?
Search Chevrolet Impala Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Chevrolet Impala Experts