Squealing sound at start up and aceleration

NOMADICALLYHAPPY

MEMBER
2000 CHEVROLET EXPRESS
5.7L
6 CYL
2WD
AUTOMATIC
160,000 MILES

Vehicle listed above is a 2500 with a V6 engine.

Started squealing at start and then only when I accelerated. Changed drive belt (serpentine belt) but 24 hours later the noise continued but this time with less emphasis.

Changed the belt tensioner and the idle pulley and replaced the belt once again (swapped it at no cost) but 24 hours later the noise returned.

I think it's important to note that when both belts were replaced, each one had a section with slight corrosion.

(Side note: I've noticed that when my A/C is running it expels more water than I would think is normal. I'm not talking about the small puddle usually created while the A/C is on. First time owning a cargo van.

Power steering, A/C and brakes function as it should.

What do you suppose I check next? Should I go through the effort of removing the belt and checking every pulley for proper rotation? Should I also check the alternator voltage?

Any advice would help. Thank you

Respectfully,

Leyanis Redondo

7 Replies

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Hi,

It sounds like something is starting to lock up. Does it happen if the A/C is off? Is it worse if you place a heavier load on the electrical system?

Let me know.
Joe

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Friday, June 12th, 2020 AT 10:47 AM

NOMADICALLYHAPPY

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When it initially happened, whenever I turned the A/C on, the noise would disappear, but after changing the belt the noise continued 24 hours later. Which is why I changed the pulley and the belt tensioner as well as replaced the belt again.

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Friday, June 12th, 2020 AT 11:10 AM

JACOBANDNICKOLAS

MECHANIC
109,700 POSTS

Is it possible for you to record the sound with your phone and upload it for me to hear? Also, let me know if there is anything that changes it. Also, which pulley was replaced?

You indicate when it started, if you would turn the A/C on, the noise would stop. Is that correct? If so, I would have expected the opposite.

Honestly, if the belt is routed properly, the tensioner is good as well as the belt, and there is no oil, grease, or coolant getting on the belt, the only other thing is if something is locking up. I attached a pic of the routing diagram just to confirm it is on correctly.

Let me know.
Joe

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Friday, June 12th, 2020 AT 11:21 AM

NOMADICALLYHAPPY

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Attached you will find the video of the noise at start, drive and turning the A/C on. You will also find pictures of the belt installation, to the best of my ability. There is one more video of the A/C running expelling water - not sure if this is normal or would attribute to the noise somehow.

The only thing that stopped the noise was when I turned the A/C on but that was before I replaced the belt the first time - which is why I thought the serpentine belt was bad. The noise continued after I replaced the belt the first and second time - and still continued after replacing the pulley and the belt tensioner. As to which pulley, I was not aware there were more than one when I purchased it at Advance Auto. You would think they would ask! Good question. How many pulley's are there for this vehicle? (Wish I had access to AllData!)

Thank you for your help!

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Friday, June 12th, 2020 AT 12:16 PM

JACOBANDNICKOLAS

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109,700 POSTS

Hi,

If there is nothing getting on the new belt, I need you to try something for me. When it is running and making noise, pour a small amount of water on the belt and see if the sound changes or goes away. If it does, then I can confirm the belt is causing the noise. If it doesn't change, we need to remove the belt and check all belt driven accessories.

I certainly do hear it and it would drive me crazy as well. As far as pulleys, they are what the belt runs on, so each belt driven accessory has one. Perhaps you are referring to the tensioner pulley.

I realize the test sounds crazy, but my intention is to see if it is something turning that makes the noise and not the belt. When you do it, just be careful to protect your eyes and clothing because the water will splash.

Also, if you look at the pic I attached (which is your pic), I circled what I believe to be an idler pulley. That has a bearing in it that can be going bad.

Let me know.
Joe

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Friday, June 12th, 2020 AT 10:59 PM

NOMADICALLYHAPPY

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The belt has been replaced with a new one twice already. I did what you asked and the noise went away when I poured water on the belt as the car was running - but of course the noise continues after the water test.

The picture of the pulley you attached was replaced as well as the belt tensioner. Those are new parts. I somewhat understand "car repair" as my dad was a mechanic and I worked at a mechanic shop for some time, although I worked in the office ordering parts and occasionally talked to the mechanics.

Is there any reason why the belt should have corrosion on it? Like I said before, when I changed the belt the first time there was corrosion residua on a section of the belt. When I changed the pulley and the tensioner, I swapped the new b3lt for another new belt and when I removed the old "new" belt it also had corrosion residue on a section of the belt. I'm thinking there is a pulley that has corrosion and I'm thinking it may be the one coming from the alternator. I don't know. What are your thoughts on this?

In either case, I will remove the belt and check each pulley for rotation.

What say you?

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Saturday, June 13th, 2020 AT 5:42 AM

JACOBANDNICKOLAS

MECHANIC
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Hi,

Okay, what type of corrosion was already on the new belt? I suspect that is the cause and not any of the pulleys. Can you identify it? Does it look like oil? Could it be coolant? Can you upload a picture of what you saw? I have seen the water pump leak from the weep hole and get coolant on the belt and cause this.

Let me know.

Joe

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