How to Replace a Serpentine Belt on a 2003 Chevrolet Impalaby Grace Mclain
The serpentine belt on the 2003 Chevrolet Impala controls all the accessories on the front of the engine: the alternator, power steering pump, water pump, air conditioner pump and crankshaft. The serpentine belt is held on by a belt tensioner that holds the serpentine belt tight on all the accessory pulleys. Once the serpentine belt breaks or slips off, these accessories will quit functioning and the engine will no longer run.
Pop the hood of the car and locate the serpentine belt routing diagram. The diagram on the 2003 Chevrolet Impala is on top of the fan shroud. The diagram will be a picture of all of the accessory pulleys and how the serpentine belt is routed among the pulleys. This diagram will give you the exact direction for routing the new belt onto the pulleys. If you cannot find a serpentine belt routing diagram, take a notepad and pen and draw out the exact routing diagram of the old belt across the pulleys.
Locate the serpentine belt tensioner. It is located below the alternator on the left front side of the engine. The tensioner on the 3.4 liter, 3.5 liter and the 3.9 liter engines will require a 3/8 ratchet to release the belt tensioner. The 3.8 liter engine will require a ratchet and a 15 mm socket for the belt tensioner. Rotate the belt tensioner clockwise to loosen and remove the belt from the belt tensioner pulley.
Slide the old belt from the belt tensioner pulley. Remove the belt from the remaining pulleys and pull the belt from the engine compartment.
Route the new belt across the crankshaft pulley first. The crankshaft pulley is the big pulley on the bottom of the engine in the center. Then route the serpentine belt across the remaining pulleys as directed by the serpentine belt routing diagram. Leave the belt tensioner pulley for last.
Rotate the belt tensioner clockwise again to relieve the tension and slide the new belt across the top of the belt tensioner pulley. Release the belt tensioner and the belt will tighten up as the tensioner applies pressure to the belt. Make sure the new belt is properly seated in all the pulleys.
Crank the engine and inspect the belt again to make sure that it stays seated in the pulleys.
- As a rule of thumb, the Impala's repair manual recommends that the serpentine belt be replaced when there are more cracks per square inch than there are ribs across the belt. For instance, if the serpentine belt is a six-ribbed belt and there are more than six cracks per square inch on the belt, it is time to replace the belt.
- Remove the keys from the ignition while you are working inside the engine compartment to ensure the engine doesn't start.
Items you will need
- 3/8 breaker bar
- 15 millimeter socket
- New serpentine belt
- Haynes Repair Manual: Complete Repair Guide for 1995-2005 Chevrolet Impala; John Haynes; 2007
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