If you own a vehicle built in the last ten years; chances are it is equipped with serpentine belts. The older vehicles came equipped with V style belts. V-belts were thinner and thicker and depending on the style of V-belt most of them were ribbed on the bottom side.
After time V-belts would stretch and their tension would have to be tightened. Depending on the belt and road progress location on the front of the motor and what components they were driving; V-belts would have to be adjusted manually in different locations on the engine.
Depending on the number of accessories the vehicle came with determined the number of belts needed to drive the accessories. If the vehicle had power steering and air conditioning then there could be up to four sets of V-belts.
When adjusting the tension of this style of belt; over tightening was common. Not only did it shorten the life of the belt but it added more stress to bushings and bearings inside the accessory components, thus shortening their life.
The advent of the Serpentine belt eliminated the number of belts on the front of the engine and also took the guess work out of the proper tension they need to run efficiently.
Serpentine belts are commonly wider and thinner with thin ribs running along the length of the belt. Most Serpentine belts are longer than the traditional V-belt; allowing this style of belt to drive more accessory components.
This style of belt does not require adjusting the tension due to the fact that there are tension pulley’s located around the front of the engine.
These pulleys have a self contained heavy spring or a rubber bushing that keep constant tension on the belt. In turn less maintenance is required and cost to maintain this concept is less.
Still, there is maintenance that is required. The belt needs to be replaced every so often but not as often as the V-style belt. Tension Pulley’s after time either lose their spring/rubber tension or the bearing that spins the pulley dries up.
In the past I have rescued several people who were broke down along the highway or interstate because the bearing on the tension pulley dried up, got hot and seized up. When this happens it usually shreds the Serpentine belt.
Since this belt drives the water pump, the engine can start to over heat if not shut down right away. It never fails; it’s either hotter than the blazing sun or extremely cold outside when these pulley’s decided to seize up. Either way you will be at the mercy of the outside elements until help arrives.
Here are some tips that will help prevent you from becoming stranded along side of the road due to either a broken Serpentine belt or seized up bearings in one of the tension pulleys.
• A Serpentine belt should last at least 50,000 miles if not more. When inspecting the belt, look at the thin ribs that run along the inside of the belt; if they are cracked it is time to replace the belt. Inspect the edges of the belt, look to see if the edges are frayed or torn. A torn edge will eventually wrap itself around the pulley and can cause major problems. Most vehicles today have two Serpentine belts. The longer belt drives the power steering pump, alternator and water pump. The shorter belt which is usually located toward the bottom of the engine and a little more difficult to see drives the air conditioning compressor. Refer to your owner’s manual to be exactly sure on what configuration you have. There is a tag located on top of the grill inside the hood that shows the specific configuration and belt routing of your vehicle.
• Tension pulleys should last at least 75,000 miles if not more. If the self contained spring/rubber bushing is starting to get weak the pulley assembly will vibrate up and down at an excessive rate at an idle. Or the pulley assembly will not run true creating an abnormal wear pattern on the belt; the pulley assembly will need to be replaced at this time. If the bearings start to get dry inside usually you will hear a chirping sound coming from the engine. This is not always the case. A bearing can seize up without giving any warning signs before hand. To inspect the pulleys make sure the engine is off. Loosen the serpentine belt so there is no tension on the pulley. Manually spin the pulley; listen to the sound of the bearing carefully. The pulley should spin freely without any resistance. There should be no noise coming from the bearing. If the pulley sounds dry or rough then it is time to replace the tension pulley assembly.
It is a good idea to inspect the Serpentine belt during every service interval. All it requires is a visual inspection that involves very little time.
I try to inspect my tension pulleys and idler pulleys every 25,000 miles. Yes I said idler pulleys. Idler pulleys are stationary pulleys. They too have bearings inside of them that need to be inspected.
Again, refer to your owner’s manual for the proper service interval. If you have your vehicle serviced at a local shop then it is a good idea to remind the service technician to inspect the pulleys.
For you do-it-yourselfers, Serpentine belts and tension pulleys are simple to replace. That tag located under the hood shows the proper routing for your Serpentine belts. The tension pulleys consist of two or more bolts that require removal. Usually it takes either a 15mm or 13mm wrench or socket to remove the bolts. Idler pulleys just have one bolt that needs to be removed. Be sure the belt is off before replacing the tension/idler pulleys.