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Dodge Ram 2002-2008: How to Replace Serpentine Belt

The accessory drive belt connects the crankshaft to all the vital accessories your vehicle needs. These are the air conditioning, power steering, alternator, and water pump. Since the Ram uses the serpentine belt to rotate the water pump, when the belt breaks you are forced to come to a stop.

By Weston Chadwick - July 17, 2015

This article applies to the Dodge Ram (2002-2008).

The serpentine belt is made of a rubber compound and is grooved for optimal friction with the accessory pulleys. A serpentine belt tensioner is used to keep the amount of friction at the proper level. Dodge recommends changing the serpentine belt between 75,000 and 90,000 miles. When the belt wears, cracks develop and it starts to stretch. This results in a loss of efficiency in your accessories as the belt slips on the pulleys. Squealing is commonly heard from slipping belts although water/dirt on the belt can cause similar sounds. Make sure the shielding around your wheels and engine is attached for full serpentine belt life.

Materials Needed

  • Serpentine belt
  • Ratchet and 15mm socket (3.7 and 4.7 engines)
  • 3/8" ratchet (5.7 engine)
  • Rubber gloves
  • Safety glasses

The procedure for the 5.7 Hemi engine differs from the 3.7/4.7 engines.

Step 1 – Remove the serpentine belt

For owners with the 5.7 liter engine, you will need a 3/8" ratchet (preferably long-handled). On the tensioner you will see/feel a recessed area where the ratchet is designed to fit into. Once the ratchet is connected, move the tensioner clockwise to release the tension from the belt. While holding the tensioner in this position, remove the belt from the most accessible pulley and untangle it out of the engine.

Owners with the 4.7 and 3.7 liter engines will need a ratchet with a 15mm socket. Turn the 15mm headed bolt on the tensioner pulley clockwise and remove the belt from the most accessible pulley. Then remove it from the engine.

  • Figure 1. The red circle indicates the location of the space where your 3/8" ratchet snaps into.
  • Figure 2. The red circle indicates the location of the 15mm headed bolt on the 4.7 and 3.7 engines.

Step 2 – Install the new serpentine belt

With the belt off, compare the sizes of both the old and new. They should be similar in length, and the number of ribs needs to be the same. The ribbed side of the belt will face the ribbed pulleys, and the smooth side of the belt will face the smooth pulleys.

Use the numbers in Figure 3 for the component locations. For the 5.7 begin by routing the belt around the alternator pulley (8) then down and around the tensioner (7). Continue around the idler pulley (5) then around the harmonic balancer (4). Next up is the water pump (2) then the power steering (3). The belt will then reach the A/C compressor. Now grab your 3/8" ratchet and turn the tensioner clockwise again. While doing so, move the last section of the belt over the second idler pulley (9). Before you release the tensioner, make sure the belt is centered over the pulleys and the ribs are correctly set into the pulley grooves. Release the tensioner slowly and smoothly.

Begin the 4.7 and 3.7 serpentine belt installation by routing the belt around the alternator/generator pulley then under the water pump pulley. Now move it over the A/C pulley and down the outside of the tensioner. Continue to move the belt over the idler pulley then down and around the crankshaft pulley to the outside of the power steering pulley. At this point you will have ran out of belt length. Remove the belt from the idler pulley or water pump pulley and install it onto the power steering pulley. Use your ratchet and 15mm socket to move the tensioner and simultaneously route the belt onto the idler pulley or water pump pulley. It's easiest to make them last because they are smooth and it's easier to slide the belt onto them. Make sure the belt is centered on the pulleys and the ribs are correctly set into the pulley grooves. Now release the tensioner slowly and smoothly.

  • Figure 3. The 5.7 hemi serpentine belt diagram.
  • Figure 4. The 4.7 and 3.7 engine serpentine belt diagram.

Step 3 – Check your work

Start the engine and watch the belt as it rides on the pulleys. Ideally you should not see it move side to side which indicates the belt is centered. If squealing is present there may be dirt on the belt or pulleys. Spray the pulleys down with compressed air. A "belt dressing" can also be purchased from your local parts store.

Featured Video: How to Replace Serpentine Belt, Dodge Ram 1500

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