Have you heard any abnormal squealing or chirping noises under the hood of your car especially when starting its engine? It may just be one of the common signs that your car may need a change in the belt tensioner.
Drive belt problems such as road debris, soil, water, pulley misalignment, worn out, belt ribs, and high temperatures, among others, contribute to damages in a belt tensioner.
Precautions should be in place to at least delay the weakening of the tensioner such as simply checking if your engine undercover is not missing.
Cost Inclusions in Replacing a Belt Tensioner
The replacement cost of a belt tensioner depends on the car type as well as the car mechanic shop that you go to. A total estimated cost range of $40 to $600 or possibly more should be kept in mind when replacing a belt tensioner – excluding other repair services and taxes.
Take note that the majority of the cost is driven by labor which is usually charged on a per hour basis and not so much about the actual parts as some car owners might think.
A serpentine belt tensioner will cost around $23 up to $199 depending on its type and brand. The actual tensioner pulley cost can start from $21 to $102 when purchasing it separately from the base.
There are two types of tensioner pulley:
- Mechanical Tensioner Pulley – this is the most common and the simplest between the two. This type of pulley needs manual adjustment and further fine-tuning is needed over time to balance the stretching that happens in the belt. This manual interference in the engine is one of its setbacks as it is more prone to human errors.
- Spring Tensioner Pulley – also called an automatic tensioner, this type uses a spring to exert tension on the belt. This pulley is typically expensive and more complicated than the mechanical one but its advantage is that it is less prone to human error.
Aside from the spring, a hydraulic damper is also included to carry the load differences and prevents the spring from bouncing off. Most of the latest car models are already equipped with this self-tensioning device.
Apart from the parts, labor cost should also be considered when changing a belt tensioner. Auto repair shops normally charge $40 to $80 per hour of manual labor depending on the location. In comparison, dealerships will have labor costs from around $95 to over $120 per hour.
The labor cost is solely the main reason why it is highly recommended that you do a one-time change of both the belt and the tensioner pulley to save on money.
With that in mind, a serpentine belt will have a price ranging from $10 to $33 which you also have to consider if you are to buy the parts yourself.
There are also available belt tensioner kits from the market that already includes a belt, tensioner, and the pulley. The cost will range from $78 to $227 depending again on the brand and car type. Make sure that the model will fit your vehicle and take note that these parts usually come with a 2 to 3 years replacement warranty.
If by any chance you stopped in the middle of a road, your vehicle needs to be towed and this is an additional $120 per hour to your expenses on the average. Most tow companies charge $3.50 to $7.00 per mile so it is more advantageous if there are nearby repair shops. Towing companies will charge a separate hook-up fee of $45.00 as a base.
There are also available mobile mechanics that do house calls which normally charges at a lower rate than stationary repair shops. They give out an average of a 20% discount on the total repair which is really a big saving since they don’t have any overhead charges compared to neighborhood shops.
You may also opt to do the changing by yourself under the guidance of your car’s manual. Most of the time, it is a simple job compared to the maintenance of other mechanical parts.
How Does It Work?
A belt tensioner is made of a cast aluminum or steel bracket with a round pulley mounted on its bearing. It spins really fast so it is critical that it runs smoothly without any sliding movements.
The drive belt tension is made up of four parts; namely, the base, the tensioner arm, the spring, and the pulley. The tensioner is usually replaced together with a new pulley and most mechanics would recommend changing the drive belt as well.
It is hazardous if the belt tensioner becomes entirely damaged while driving. It is a pulley that works alongside the long drive belt at the front of your car’s engine. It maintains the tension on the belt to properly drive the car alternator, air conditioning compressor, water pump, and power steering pump among others.
Basically, the tensioner presses against the belt to create the stretch that is needed to properly run the other pulleys that are connected to other car accessory parts. It keeps the belt on course while it goes around the engine.
If the pulley’s bearing becomes loose, there would not be enough tension on the belt so it will either cause the squealing or it becomes hot. There is also the possibility that the belt may come off causing the other car accessories to stop. This can also cause the engine to overheat because it will directly affect the performance of the water pump.
It is not one of the maintenance parts in a car so it is usually overlooked by car owners unless any abnormalities are seen or heard. It is not a part that undergoes the regular wear-and-tear so it is usually expected to last the lifetime of a vehicle.
Cars that have high mileages should be regularly inspected as most cars get replacements before reaching the 125,000-mile mark. It is recommended that whenever your vehicles get their serpentine belt checked, the tensioner should also be examined.
Belt Tensioner Noise Issues
Each sound has its own characteristic that leads to a specific cause and one method to detect the problem is by using a water bottle and spraying it on the rib side of the belt. This is done while the engine is running.
If the noise gets louder, then it’s a squealing sound that is usually caused by either a low installation tension or the tensioner spring has been damaged. If the noise clears out, it is a chirping sound and this normally points to a pulley misalignment or worn out bearings.
Symptoms of a Belt Tension Failure
How would you know if your belt tensioner is already nearing its lifespan? Here are some indicators that will be useful for every routine check-up of your hood:
- Discernable Cracks and Rust Bleeding
You will be able to notice rusting around the arm and the base of the tensioner. Any cracks or damage to the housing, arm or its bracket warrants a change in the tensioner. These signs are usually seen when you remove the tensioner from the engine.
These signs indicate that there has been internal wear of the component. Pay extra attention to the part of the tensioner where it stops and the mounting bolts as this is normally where the cracks start.
- Pulley Bearing Wear
The typical cause for this is that the pulley bearing itself is defective and this causes noises when you manually rotate the pulley. After removing the belt, rotate the pulley and if there is any resistance or noise, the problem is most probably in the pulley bearing.
You have to replace the whole tensioner as well and not just the pulley bearing part. This will only cause further failure in the whole assembly.
- Pulley Wear
This is caused by the serpentine belt wearing into the pulley as it goes around it over time. Pulleys are made from nylon, plastic or steel and should have a flat, smooth surface. Some pulleys are also designed to have grooves on them.
A good pulley is one that has a flat surface without any dents or cracks in it. For the grooved pulleys, these should be free from inserted dirt and do not exhibit any visible cracks or dents as well. The plastic pulleys should not have cracks or breaks on the sidewalls especially on their fins.
- Misalignment of Tensioner Assembly
Probable causes for this may be an improper alignment during the last tensioner installation or there has been rusting between the base and the mounting surface. A deformed mounting connector is also a possible cause for misalignment. You may be able to observe this if there is an unusual belt tracking on the tensioner pulley.
- Tensioner Noise
Make sure that the air conditioner or fan is on, the wheels are turned ¾ to the left or right, the defroster is on, and the lights as well, to properly diagnose a noise coming from the engine. If a high-pitched squealing noise is produced, this is most probably because of loss of tension in the serpentine belt. This is the second most common cause of noises from the belt.
A rattling noise in the tensioner area may indicate corrosion in the internal parts and this means that it is nearing its failure. A grinding noise, on the other hand, may be a result of damages on a bearing pulley assembly. You may confirm this by revving up your engine and continue to hear the grinding noise from the engine.
- Tensioner Arm Misalignment
The usual cause for this is the metal contact between the arm and the spring housing of the tensioner. You will be able to notice scratches or marks on the tensioner arm due to the abnormal belt running on the tensioner pulley.
- Excessive Tensioner Arm Oscillation
This is where there is too much swaying of the tensioner arm when the engine is on. Continuous swaying indicates that the damping system or spring torque has been damaged. These parts are responsible for absorbing the vibration before it reaches the belt drive system. If this happens, there will be a premature failure of the engine.
- Grinding Tensioner Arm Movement
This is a red alert to replace your tensioner if there is a binding or grinding when turning the tensioner arm using a wrench. In order to check this, move the tensioner throughout one revolution by applying force into the arm. If there is any grinding or binding while twisting it, then, there is a definite need for a new tensioner.
- Loss of Spring Force
Manifestations of this concern include squealing from the belt slipping from the tensioner or the belt stops from completely rotating. It is important that there is still resistance when moving the tensioner arm as it is mounted on the engine. If there is no resistance, then the force of the string is already gone.
- It is always better to replace the serpentine belt together with a new belt tensioner especially if the belt has come off due to a damaged pulley.
- Test the other belts while the serpentine belt is off. This is a good opportunity to replace other secondary worn out belts.
- It is also a good time to check the condition of free-wheeling pulleys like the alternator when replacing the tensioner.
- You also have to be prepared for any other repairs the technician might want to do while inspecting your belt tensioner. The repairs may also include other nearby or similar accessories to that of a belt tensioner that might also be worn out already.
- If you are to do the changing by yourself, make sure that there is an available torque wrench with small increments to be used in tightening the bolts. This is to avoid over-tightening or under-tightening the tension which will be very costly in the end.
Always set aside a regular visual inspection of your belt and its pulleys as you do every oil change. This will help extend the life of your vehicle as well as ensure safety while driving.