2021 3.5 Ecoboost Belt Squeal

[dharmon012]

Hi all,

I have a 2021 3.5 ecoboost with roughly 90k on it. The belt has been squealing for about 40k now. It seems worse when it is damp out or humid, but also when it's cold.
I swapped the belts on it thinking they may be old and slipping but it didnt solve the issue.
Google search lists new belts, worn out idlers, or worn out tensioner.
Any insight before i throw parts at it? This squeal drives me crazy.

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[jkosh22]

Did you replace the stretch belt too? Or just the alternator belt? I had a buddy with a 22 that chirped when cold or damp and replaced the stretch belt and that fixed his issue.

 

[dharmon012]

i replaced both belts

 

[zx6roclet]

Mine has done this every cold am since new as well…. 23 tremor

 

[jkosh22]

You could try running it without either and that will pinpoint if it’s the ac belt or alternator belt. Tensioners are the first place to start. Spin all pulleys hand and check for a resistance or rough spinning. Also could spray a little penetrant on just the belt and that would also tell you if it’s a belt or a pulley. If the noise stops, it’s just a belt. Not uncommon to have new belts squeak also.

 

[dharmon012]

ill give that a shot. Thank you

 

[zx6roclet]

.

 

[MrMaighan]

I have the same problem with my 2021 F150 3.5. I sprayed the belt as a temp fix and it went away for the most part. I want to change the belts but can't find the stretch fit AC belt. Anyone know what part fits that? Also, why is the stretch fit in front of the main belt? All the videos on how to change the belts has the AC belt closer to the engine so you could remove the other belt without taking it off. Not mine, stretch fit is on top.

 

[dharmon012]

Napa had them for me and yes my stretch belt was in front as well

 

[MrMaighan]

I guess I'll try Napa. I went to O'Reilly's and AutoZone, and they could not find it in their computers. I also tried Amazon but with no definitive this fits your truck results.

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