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Knocking noise around serpentine belt and pulley?

Tiny
TEAMCALIJUJU
  • MEMBER
  • 2017 FORD EXPLORER
  • 2.3L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 160,000 MILES
Knocking noise coming from serpentine belt/water pump/pulleys area. Narrowed down to this area by taking off the serpentine belt and running engine. Sound does go away when belt off. Replaced idler pulley, tensioner pulley, serpentine and A/C belt. Noise still there after putting back together. Any suggestions?
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Wednesday, November 15th, 2023 AT 10:59 AM

11 Replies

Tiny
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Hi,

When the belt is off, spin all belt-driven components to see if any of them feel rough. You have already replaced several things. Check to make sure the water pump doesn't have play in the pulley. Also, confirm the A/C compressor pulley spins smoothly.

Let me know.

Joe
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Wednesday, November 15th, 2023 AT 8:35 PM
Tiny
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The water pump does in fact have play. I can manually spin it around without issue, especially when the belt is off. I have no issues with getting cold or hot air, but my engine has overheated but went back down to normal as soon as I let off the gas. Thoughts?
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Wednesday, November 15th, 2023 AT 10:23 PM
Tiny
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Hi,

If there is up and down, side to side, or in and out play, the bearing is likely faulty. That could be the source of the noise.

If possible, record the noise and upload it for me to hear.

Take care,

Joe
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Thursday, November 16th, 2023 AT 7:59 PM
Tiny
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Update. Replaced water pump and pump pulley. Noise still there. And again, only present when belt is on or when I apply or reduce pressure on the tensioner. I've uploaded a video. Sounds like a faulty alternator pulley/bearing. Not sure.
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Friday, November 17th, 2023 AT 12:20 PM
Tiny
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Hi,

Wow! I certainly hear it. I wish I would have heard that before you replaced the pump. Make sure nothing is hitting. Also, when this is making the noise, does the belt jump around at all? Also, with the belt removed, does anything feel stiff, like it is rough when turning?

Also, does the sound change if you turn the AC on or turn the steering?

Let me know.

Joe
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Friday, November 17th, 2023 AT 9:39 PM
Tiny
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The belt doesn't look to be jumping around more than what I would assume to be somewhat normal. It's an aftermarket bando belt and its brand new but the noise was also there with the old belt on. And as far as AC/heater both work as they should and don't change the noise either way. Neither does it change when turning. What do you suggest it might be? Thanks
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Friday, November 17th, 2023 AT 11:49 PM
Tiny
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Hi,

That is a good question. Have you removed the belt again to check all the pulleys to make sure there are no issues? Also, just to reconfirm, the sound isn't present when the belt is off, correct?

Let me know.

Joe
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Saturday, November 18th, 2023 AT 9:17 PM
Tiny
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What do you suggest it might be? Are you AI or something. What happened to getting answers for questions. I'm just getting question for question without any answers.
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Saturday, November 18th, 2023 AT 9:19 PM
Tiny
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Hi,

No, I'm not AI. LOL, I feel it is one of the belt-driven accessories that has a faulty bearing. Since it doesn't make noise with the belt off, it has to be one of them. The only way to check is to remove the belt and inspect each component. Not being there limits what I can determine as the cause. However, that is what will need to be done unless you have an automotive stethoscope and can carefully listen to each accessory to determine which one is making the noise.

From here, that's the best I can offer.

I hope you understand.

Joe
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Saturday, November 18th, 2023 AT 10:03 PM
Tiny
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Lol. I apologize. You never know these days. So, my next step is the alternator pulley. I can turn the pulley both ways with a flat head inserted. I read that it should only turn in one direction. Also, it makes noise and moves somewhat when I spin it manually. Thats literally the last pulley I haven't replaced. I don't suspect the alternator because I have no issues with starting the car, no lights flicker, etc. Thoughts? Also, could it just be a lose belt (which I just put a new one in but not OE).
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Saturday, November 18th, 2023 AT 10:39 PM
Tiny
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Hi,

The alternator can turn in either direction. However, keep in mind, although it is charging, the bearing still could be faulty.

The idea that you have replaced everything, like you, I suspect the alternator must be it.

Let me know if that resolves the issue. I just had an idea. Remove the alternator and have it bench tested at a parts store. They actually put a belt on it and spin the alternator. Hopefully, that will tell you if that is the issue. It's just a thought, but it may help.

Take care,

Joe
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Sunday, November 19th, 2023 AT 7:49 PM

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