Serpentine belt squeals at startup, when in drive or reverse and when A/C turned on

Hi,

Is the belt tight? Is there anything getting on it such as coolant or oil?

If I understand, it makes noise and then stops and is worse with the AC on. When you have the belt removed, are any of the belt-driven accessories seem hard to turn?

Here is information for testing the belt auto-tensioner. I realize you replaced it, but confirm it is working properly. The attached pic correlates with the directions.

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2006 Mazda 6 L4-2.3L
Drive Belt Auto Tensioner Inspection
Vehicle Engine, Cooling and Exhaust Engine Drive Belts, Mounts, Brackets and Accessories Drive Belt Tensioner Testing and Inspection Component Tests and General Diagnostics Drive Belt Auto Tensioner Inspection
DRIVE BELT AUTO TENSIONER INSPECTION
DRIVE BELT AUTO TENSIONER INSPECTION
1. Remove the drive belt.


pic 1


2. Verify that the drive belt auto tensioner moves smoothly in the operational direction.
- Replace the drive belt auto tensioner if necessary.
3. Turn the drive belt auto-tensioner pulley by hand and verify that it rotates smoothly.
- Replace the drive belt auto tensioner if necessary.
4. Install the drive belt.

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If possible, record what it is doing so I can hear and see it. That will help me.

Take care,
Joe

The tensioner was not replaced. I replaced the bearing of the pulley. the belt I put the size we measured from the one that came with the car, I removed the one that was too tight, the belt does not have any coolant or oil on it. it squeals at startup and stops immediately, then it starts when the A/C is turned on, it only squeals when the car is not moving, when I am drive on (accelerating) it does not make any noise. when I come to to a stop it starts again. When the belt is removed all the accessories turns smoothly by hand.

Could this be the tensioner?

Hi,

I need you to confirm the model. Is it a Mazda 6 or 626?

When the car first starts, a brief heavy load is placed on the alternator which can cause this. If that is the only time it does it, it sounds like a tension issue.

Let me know if I can help.

Joe

Hi, it is a Mazda 6. it does this at startup and and when I turn on the A/C while the car is on in park or even neutral, it gets worse once I put it in drive or reverse then stops when i am driving. it also squeals in the evening when the weather is cool when I put it in reverser or drive even if the A/C is off, but stops to squeal while I am driving it and starts again when I stop while in drive or reverse, it does not squeal when it is on park of neutral if the A/C is off.

Hi,

I have t be honest, it sounds like the belt isn't tight enough. Specifically, the belt that runs the alternator. Have you checked the tensioner?

https://www.2carpros.com/articles/car-squeaking-noise

https://www.2carpros.com/articles/how-a-serpentine-belt-tensioner-works

I'm not sure why, but I have to go to 2003 for the Mazda 6. In 2002, it is showing the 626. It may be based on where you live.

Here are directions for testing the tensioner. See if it helps.

DRIVE BELT AUTO TENSIONER INSPECTION
1. Remove the drive belt.


imageOpen In New TabZoom/Print


2. Verify that the drive belt auto tensioner moves smoothly in the operational direction.
- Replace the drive belt auto tensioner if necessary.
3. Turn the drive belt auto tensioner pulley by hand and verify that it rotates smoothly.
- Replace the drive belt auto tensioner if necessary.
4. Install the drive belt.

Let me know.
Joe

Hi, sorry for the late response. I was sourcing for money to get a new tensioner. I got a new tensioner and replaced it but with no luck. the squealing is still there. what really can I do to stop the squealing?

What kind of belt are you using? the manufacturer? also can we get a video of you showing us the belt tension?

Sorry for the late reply, i was away from home.

The belt looks good, so the next thing is to confirm it is in good condition. Does it appear dry, cracked, or anything that could cause this? If it is tight, I'm wondering if there is an issue with the alternator putting too much of a load on it.

However, I feel it is truly related to the belt itself. Are you certain it is the correct belt for this vehicle?

Can you record it when starting so I can see what it's doing?

Joe

The belt does not have any cracks, it is 5 months old. the size of the belt was measured from the original belt that was on the vehicle. I am not sure what you mean by dry but it does not have any liquids on it. I will make a video at startup and upload

this is a video at startup. A workmate was suggesting that maybe it could be the crankshaft pulley, does the crankshaft pulley squeal?

This one is the original belt i removed from the car. (6PK2275)

The images below is the smallest belt (6PK2260) I tried on, just to see if the squealing will go away but did not go away, after using it for about 3-4 weeks I decided to remove it and found it had cracked up not sure if the tension was too much. I tried it because when I visited the link below this was the size showing up for my car.

https://www.buycarparts.co.uk/mazda/6-gg/16685/10531/v-ribbed-belt

The size of the original belt that came with the car is 6PK2275.

I cannot find the belt routing for his vehicle.

Maybe y'all can!

Just to throw something in there that may not be obvious.

I have seen other vehicles whereas just putting the belt on the way one might "think" it should go, the belt would closely fit and the tensioner might provide some tension.

In all actuality, the belt was routed incorrectly,

If it had been correct, the tensioner's "turned or twisted" position would have been "clocked" as it was originally and tension would have been correct. (does that make sense?--I don't mean the tensioners mounting, I mean its movement in order to hold the belt)

I had seen this misrouting on other cars, and when through trial and error or finally finding a diagram, we used a magic marker to draw it in a conspicuous spot under the hood so that the confusion would not happen again.

Just a thought.

The Medic

Hi Medevac, the image below shows the diagram on how the belt sits on my vehicle, and it is routed exactly as seen in the picture.

the belt in the picture is no good please install a new unit, also once installed check the tension. Can you please shoot a quick video with your phone so we can see what's going on? that would be great. You can upload it here with your response.

Hi Ken, i uploaded the video earlier and the belt on the vehicle is in good condition. you can refer to the earlier video i posted. thank you

that does not sounds like a belt issue, I would remove the belt and turn each accessory by hand to see you you can find the bad bearing in one of them I suspect the belt tensioner or idler pulley is bad. Check out the diagrams (Below). Let us know what happens and please upload pictures or videos of the problem.

Hi,

I listened to the video and did hear it. If the belt is tight and good, something must be on the pulleys. Make sure nothing is leaking on them. Also, try removing the belt and cleaning the pulleys with something like brake cleaner.

Let me know if that helps.

Take care and God bless,

Joe

Hi Ken, thank you, but the i have change most of the accessory, i have replaced the following: tensioner (together with the pulley), idle pulley, i replaced the bearing in the A/C pulley, and i replaced the steering pump and the belt, the only things not replaced is the alternator and the crankshaft pulley. i had tried on a different alternator but the noise did not go away.

Hi Joe, i don't have any licks on the vehicle and the belt is dry, there is no liquids on it. the size of the belt is the same size as the belt that came with the vehicle.

Honestly i feel like changing the crankshaft pulley because i really don't know what to do now.

In the past, I have seen pulleys that caused a noise simply because they had road dirt, oil, and other things on them that you really couldn't see. Just for the heck of it, try cleaning all the pulleys with something like brake clean. It won't hurt to try. Focus on the crank pulley. Keep in mind, if there is something there you can't see, it will already be on the belt, so take a rag and wipe it down really well.

Joe