How Tight Should Serpentine Belt be and How to Tighten it?

The engine starting to make weird sounds or the AC stopping working in the middle of the road can be a horrifying experience. But if it really happens, ever wondered what you are supposed to do?

Your vehicle’s engine or other electrical components can stop working suddenly if there is a problem with the serpentine belt, which means it’s either tight or loose. So, you need to know how tight a serpentine belt ought to be and how to tighten it in order to save yourself from that horrible situation.

So, how tight should the serpentine belt be? It should be in a middle range that is highly suitable for your engine system. Ideally, it shouldn’t bounce more than o.5 inches when you twist it from the center.


What is a Serpentine Belt?

Like most other complex parts of an engine, a serpentine belt is a strong rubber belt that controls most of the accessories inside including the alternator. Tension is a very important thing to maintain when it comes to a serpentine belt. It mostly works by a number of pulleys.

Some of the crucial parts of the engine system such as an air conditioning compressor. The air pump, power steering pump, and water pump rely on this belt for uninterrupted operation.

This belt usually makes connections between all the devices in the system and makes them work properly. Generally, an auto-tenser or an adjustment screw comes along with the belt to apply the appropriate tension needed to work these devices.

If in any case, the belt stops working or gets loose, there are many likely possibilities of your steering losing control or the engine getting overheated.


Effect of Tension on the Efficiency:

As I mentioned earlier, the Serpentine belt’s efficiency depends highly on its tension. This means that the tighter the belt is, the better will be the result and performance of the belt.

This tension is the one that keeps the devices tight and connected to the pulleys while preventing the belt from flipping over.  This applies to everything including the air conditioner and steering.

So, if for anything the belt twists, flips, or stretches while doing its job, it will wear out soon choking on the engine accessories and you will see the bad effect on their performances almost immediately. Worse, your engine might stop working suddenly in the middle of the road.

That happens because the tension is not in a proper amount, and the engine starts to consume more power than usual which will have an effect on everything of devices including efficiency and performance.

So, you need to check the tension of your serpentine belt regularly to make sure that everything is working properly.

Now, your serpentine belt must be tightened in a way that’s not too much for the system or too loose that will stop working. It’s really important for this belt to be tightened in an appropriate amount because the pulleys and connections will come off otherwise. But how tight it should be dependent on the engine system you are using.

You don’t want the premature failure of the bearings and connection lost in your devices, do you?


What Are the Signs of a Problematic Serpentine Belt?

It’s normal for the belt to slip, crack or flay as it gets older and starts to wear down or the rubber parts peel off. If the belt really cracks, it will be at risk of getting filled with toxic fluids or misaligned. So, you need to identify the problem immediately before it goes too far.

These are the most common symptoms of a failed serpentine belt:

Squeaky Noises: You may hear squealing noises in the engine of your belt if it starts to slip off. That means either the belt has a low tension or is having a belt stretch. It can also mean that the belt and pulley are not properly working together.

  • Cracks or Wears: sometimes your serpentine bell might also show some physical damages that might include cracks, wear, chunks, or rib separation.
  • Steering or Air Conditioning Failure: Your serpentine belt might be telling you something if your steering or AC stops working suddenly. Also, the alternator or water pump may add to these signs.
  • Vehicle Breakdown: If your serpentine belt reaches an extreme condition and you have been using the vehicle anyway, it will result in the ride stopping midway through your driving.

The engine light might also start sending you signs. You should never ignore any of these symptoms if it feels like a serpentine belt problem.


How Tight Should Serpentine Belt Be?

You know that you need to check your serpentine belt when the engine starts producing loud squeaky noises. Whenever this happens, you must check the position of the belt immediately.

If you don’t do anything in time, the belt will slowly go over the pulleys, and removing the connections will result in a sudden breakdown of the engine.

The most proper tension measurement of a serpentine belt is that it mustn’t bounce more than 0.5 inches when you twist it from the center. From this position, it will get loose if you twist more and it will get tight if twisted less

Make sure that the belt is in the right position, with not too much tension on the serpentine belt, not too less tension. Both of these positions will result in a serious outcome.


How to Tighten a Serpentine Belt?

Now that you know how important it is to get the serpentine belt in the right position, you will have to know the steps for tightening it. In this part of the article, I am going to give you a brief idea of how to tighten a serpentine belt.

Always remember, the belt should not be too loose or too tight, just perfect!

Conventional Procedure:

In most vehicles, the tension of the belt is controlled by a generator that is placed near the engine.

You need to move the generator either away from or towards the engine to adjust this tension. Generally, you can adjust the belt with the pivot screws on the generator which needs to be loosened or tightened.

In this case, you need to take the generator away from the engine with a tool like a hammer handle to tighten the belt properly. Then, loosen the screws from the pivot part and pull in the belt. Make sure the tension is right. If so, bolt back the screws to the pivot.

Use a hammer handle to move the generator towards the engine in order to loosen the belt. You can pull the belt out after loosening the screws from the pivot.

Again, check the tension, and if it seems right, both back the screws.

Contemporary Procedure:

Now, in modern days, the engines come with an automatic belt tensioner featuring a pulley arrangement. This is one of the most useful tension fixers invented till now.

With this arrangement, adjusting the serpentine belt tension is not only easier but also more manageable than moving the whole generator part.

You need to get to the tensioner pulley in order to adjust the tension of the belt that’s in the pulley system. You should look in the instruction manual to get help with this process.

After that, get almost one-half of the pulley out. Then twist the screws both anti-clockwise and clockwise with a spanner tool to adjust the tension.

Measure the twist margin and tension by rotating the belt. Everything’s fine and in the right position, tighten the screws back. Put the pulley covers back and turn the engine on to check the vibrations of the pulleys and bearings. Also, make sure the serpentine belt is spinning in the right way.

If you find any jam in the movement, you will have to open up the pulley cover again and correct the screws bolting. However, make sure that the belt alignment doesn’t move while you try to adjust the tension.

Then again try to start the engine after putting the pulley cover back. You need to keep doing this step continuously until the serpentine belt starts spinning smoothly and the engine stops making squeaky noises.

Importance of the Tension:

You must have had a good idea by now how important the tension of the serpentine belt might be on your vehicle’s engine. If the tension is not right for anything, the noise produced by the engine should be enough to let you know about the problem!

Also, both loose or tight belts will cause the devices to be dysfunctional leading to the wear of the belt. This will also lead your vehicle to lose efficiency eventually.

Based on what I mentioned earlier, you need to pay attention to the belt’s condition before it gets too late. Also, you need to check the instruction guide for more information regarding the tension.

Generally, the tension of the belt can get disturbed due to the daily use of the straining over the belt and needs to be corrected all the time.

But if you maintain a regular checkup on the belt and use it carefully, it will give you service for a long period of time. So, in order to enjoy a lovely ride on the road always, you need to check and maintain the belt regularly.



So, I hope now you know how tight should the serpentine belt be. While the tension is a key element of your engine working properly, it can also be the cause of your vehicle’s most electrical problems.

Hence, you should never ignore a serpentine belt problem. You don’t know what a simple squeaking sound might lead to.

Always read the instructions manual before starting to fix your problem. But if you are not confident enough, ask a professional to do the job for you.

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