Changing Your Serpentine Belt

Squealing from under the hood?

It might just be a wearing serpentine belt


Drive Belt replacement

How to change a serpentine belt


You wake up in the morning, start the car up and hear a strange squealing noise coming from under the hood. You decide to drive anyways and the noise magically dissapears. Must have been nothing right? Nope chances are you have a serpentine belt that’s on it’s way out. In most cases the serpentine belt is to blame for high pitch squealing that can come and go as it pleases until one day it snaps.

The squeal coming from the serpentine belt actually happens when the alternator needs to add more power or less to the car causing the belt to move around more than it usually does. Any “minor” defects to the belt will cause a noise.

It’s best to get this fixed as soon as you can because if the belt snaps it wont necessary damage your car but it will make your alternator useless, meaning there will be no charge to your car. If the serpentine belt is snapped your car will soon run out of juice and you will be stranded.

In a worst case scenario it can warp the alternators bearings which im afraid to say will require the use of a replacement alternator. Don’t try and repair alternators they are not worth the aggro. See our guide on how to change your alternator if you require a new one.

I recently changed my serpentine belt on my car and found it to have cracks everywhere. Im surprised it didn’t snap off as I was driving. Funny thing is I had bought a replacement serpentine belt the week before just never got around to swapping them over. Lesson learnt!

If your hearing any kinds of squealing coming from under your hood it’s best to check the serpentine belt first before performing anymore checks on the car.


How to check if your serpentine belt is to blame


Firstly you will want to locate your serpentine belt. They are quite easy to locate they are attached to the side of your engine on 2, 3 sometimes 4 or more small pulleys this belt then extends to your alternator. See picture below:


Here is a side view of your serpentine belt

Full view of your serpentine belt –


It’s really not that hard to find as it’s the only belt attached to the alternator. If your having problems locating your serpentine belt then seek help from your car owners manual.

There are a few things you can look out for when it comes to checking for a faulty serpentine belt. Follow this checklist to ensure your serpentine belt is in good health.

High pitch squealing on cold start ups

You will first notice a squealing during cold start ups. This is because the car needs more power to help the car turn over. Also not to mention the heating you may have on in the car. Any squealing coming from your car needs to be addressed as soon as possible. It may not be the serpentine belt that’s to blame it could be other belts, pulleys or both.

Grease or dirt on the serpentine belt

Open up your hood and locate your serpentine belt as shown in the previous picture. Once you have located your belt first look at it from above for any dirt or grease. Then rub your fingers across the belt if there is any dirt on your finger then there may be an oil leak or some mud has gotten into the engine bay. If there is any oil leaks make sure you locate the leak before changing your belt.

Cracks on the serpentine belt

You may not be able to see these without taking the belt off but in some cases it is quite easy to just touch the belt and feel cracks in it or missing ribs on the belt. If you have any doubts about the condition of the belt replace it there only around $30 for a new one.

If you have noticed any of the above problems it is common sense to replace the serpentine belt now before it gets in a much worse state. You can still follow our guide if you are just interested in DIY car repair. This is a relatively easy task to complete and in most cases does not require the removal of your car bumper (but bare that in mind!).


Tools required when changing your Serpentine Belt


Here is a list of tools you will need to change your serpentine belt. Bare in mind some cars require “special” tools when it comes to doing work on them. It’s in your best interest to purchase the tools listed here as most of them if not now, will come in handy later on. Always check your car owners manual if you are having any doubts when installing your serpentine belt.

Set of Wrenchs 10mm – 25mm

You will need a wrench to turn the bolt that is holding your serpentine belt in place.

Set of Allan Keys and Torx Security Keys

The tensioner has an Allan key style lock sometimes a Torx lock on it that needs to be loosened before the bolt can be turned. Never unscrew these bolts all the way off unless you plan on changing the pulley too.

Or A Serpentine Belt removal tool


Serpentine belt removal tool


If you want to save yourself time and the aggro of trying to get to the serpentine belt you can use a serpentine belt removal tool to remove the belt. This guide does not involve using one of these tools. The tool is just basically an allan key and wrench in one.

You can purchase one of these from all over the net there are plenty available on amazon and ebay.


Where to begin?


Right now we are ready to get the job done firstly you will need to park your car up on level ground make sure your handbrake is on. We don’t wan the car rolling whilst your working on the car. Please note in rare cases you may need to remove the drivers side wheel to get to your serpentine belts tensioner. Just bare this in mind in case you need to remove the wheel to make adjustments to the serpentine belt.

Now open your hood and locate your belt. If there are any wires, hoses, or general housing blocking your belt you will need to remove these and make sure you put them back in when you have changed the serpentine belt over.


serpentine belt removal

Top view of serpentine belt


Now that you have located your belt and there is enough room to work in you can remove the belt.

Removing the serpentine belt


Before you do anything get a pen and paper and draw the belts location on your engine. Which pulleys it goes on is vital when putting the serpentine belt back on the car. One thing to remember is that the belt has two sides a ribbed side for the ribs on the pulleys and a smooth side for the smooth parts on the pulleys.

Now if you have the serpentine belt removal tool just follow the instructions that came with the tool. If your working with an allan key and wrench you will want to have a bit of patience with this one.

Drive Belt replacement

Torx key required for this tensioner


As you can see from the above image a torx key needs to be inserted into the middle and a wrench needs to be placed on the outside (see photo below). Since your working from the top of the car it can be quite fiddly to get your wrench and key in the correct place. Once you think you have got your tools in the correct place turn the allan key first (anti clockwise) and then the wrench bolt will just come loose. You do not need to loosen this up all the way only a little will be fine. Your only taking the belt off.


how to change a serpentine belt correctly

Wrench and key in correct location


Installing the new serpentine belt


Just do the previous steps but in reverse order. Make sure you take your time when installing the new Serpentine belt the last thing you want to do is damage the serpentine belt on a sharp edge or get frustrated and stretch the belt. Remember the tensioner moves up and down if it doesn’t loosen it up a little more to give yourself more room.

When your sure the serpentine belt is on correctly your going to want to tighten the belt up. You should tighten the belt up to the correct tension which should be written in your car owners manual. If your belt is to tight or too lose will either snap, squeal or fall off.

First get your wrench around the bolt and push it as far as you can clockwise. This will tighten the belt up, to set the correct tensioner you then just tighten the allan key up and it will sit at that tension. The tip is to not tighten it too tight or too lose. If in doubt check your car owners manual.

If you don’t have a tensioner and want to tighten your belt without one then make sure there is “little” play in the belt and always test your belt before performing long journeys.


Testing your Serpentine Belt


Now that you have successfully changed your serpentine belt its time to test it out. Follow these steps:

  1. Turn on your car make sure the car is in neutral.
  2. Rev the engine a few times.
  3. Turn off your engine.
  4. Turn your engine on again with the air con on (heater/blower). Wait 5 minutes.
  5. Now take the car for a 5 minute test drive.

If your belt doesn’t squeal chances are you have done the job correctly. If you notice any squealing pull over when and where it’s safe, then check the serpentine belt and readjust if you have to. I kept my tools in the car and had to re adjust my belt 5 hours later in the middle of no where as the belt was put on too loose.

It really is that simple to change a serpentine belt the hardest part is probably getting your hands into the engine bay to reach the serpentine belts tensioner pulley. But when you have done it once before it’s simple the next time.

Bare in mind if you would have taken this to the mechanic for a change they would most likely have changed the tensioner and pulley aswell which can set you back around $100 – $200 so go grab yourself a cold one you have deserved it!

Leave comments if your struggling with your serpentine belt and we shall try to help you fix your problems.


Regards, The Beat The Mechanic Team