Swapping Out Your Serpentine Belt
The accessory drive belts of older cars have mostly been replaced by a single serpentine belt on newer cars. Instead of a single v-groove belt driving individual accessories, most cars now have a single multi-groove serpentine belt that drives all the accessories. When and why this belt should be replaced is the same as v-belts found on older cars; cracks in the belt, cuts in the belt, and the belt being stretched and squeaking are all reasons to replace it. Most carmakers also set regular maintenance intervals, usually between 50,000 and 75,000 miles, for changing this belt, to prevent it from breaking unexpectedly while driving. Here’s how to change the serpentine belt on your car. The exact procedure will differ a little from car to car, but will generally be the same no matter what kind of car you own.
Tools You’ll Need
- New serpentine belt
- Ratchet with socket set
- Adjustable wrench
1. Make Note of Belt Routing
This is by far the most important step in changing a serpentine belt. Most cars will have a belt routing diagram under the hood somewhere. If yours doesn’t, draw it. The drawing doesn’t have to be a Michelango masterpiece, just one that you can understand in order to properly route the new belt.
2. Remove the Old Belt
Older v-groove belts, or fan belts, were tensioned by prying the driven accessory around a pivot point and tightening the nuts or bolts securing it. Most serpentine belts make use of a belt tensioner for this. The tensioner is rotated away from the belt to create enough slack in the belt to remove it. On some cars this is accomplished using a ratchet in a square-drive opening in the tensioner, whereas with others, a socket is needed. Still others have a square extension on the tensioner that requires a wrench to rotate the tensioner off the belt, giving you the required slack.
Using the proper method for your car, rotate the tensioner off the belt creating the necessary slack and push the belt way from the engine. This will create even more slack and the belt can then be removed completely from the car. Carefully release the tensioner, allowing it to move back without snapping back, which can damage it and other components.
3. Route the New Belt According to Your Diagram
Here is where you need to refer to the underhood diagram or the one you drew in Step 1 above. Improper routing of the serpentine belt can cause damage to driven accessories, especially the power steering pump and air conditioning compressor.
Route the belt around all of the accessory pulleys until you reach the tensioner pulley.
4. Release Tension on Tensioner and Finish Belt Installation
Using the method to relieve tension in Step 2 above, rotate the tensioner pulley until it is in such a position as to allow you to slide the serpentine belt over it and slowly let it spring back and tighten the belt. Again, do NOT allow it to snap back in place, as damage can occur. You’re done.
Additional Notes
On some front-wheel-drive cars, you may have to support the front (passenger) side of the engine and remove the right-side engine mount to remove and replace the serpentine belt. In this case, use a jack with a block of wood under the front (passenger side) of the oil pan to support the engine prior to engine mount removal.
When releasing the belt tensioner, make sure your fingers are not placed so that they can be pinched by the belt as tension is applied to it. Trust me, it hurts if this happens.
Photo credit: Flickr CC igloowhite
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