Why is car overheating on 2003 Buick Rendezvous

Replace thermostat, water pump. At 50,000 miles had service of manifold done at a cost of 1200 by Buick dealer

1 answer
Overheating can be caused also by a malfunctioning cooling fan, an air flow issue through the radiator, and even an air pocket in the cooling system following thermostat and water pump repairs.