Pulley squeal ?

I have a 2014 Tacoma 93k miles and has been squealing as soon as I go over 10mph, replaced the serpentine belt last night with a brand new bando belt and the squeal is still there . Any ideas on how I can tell if or which pulley is the culprit ? I spinned all of the pulleys by hand and none of them wobble or make noise when spinning . Could it be my tensioner as well ? Noise goes away as soon as you drop
Below 10pm it cuts the noise off , ac does not affect making the noise appear or disappear so I’m thinking pulley

 

If you want to diagnose yourself, then my suggestion is to get a stethoscope and probe the pulleys.

 

A stethoscope is your best bet, otherwise i've found that when a belt is squealing that it's also shedding material.For persistent squeakers i've found that you sometimes have to wire brush the grooves of grooved pulleys to remove the old belt material to quiet things down.

In theory, a belt is not driven by the contacts of the "peaks and valleys" of the belt and pulleys but by the sides of the "peaks and valleys". If the "peaks and valleys" of the belt and pulley bottom out, then you get belt slippage i.e. noise.


This is easier to see on a v-belt setup as it's just one big peak on the belt and one big valley in the pulley. Looking in at the side of that setup or the polished witness marks on the pulley, you'll see that the belt rides on the sides not on the top. Same thing with a serpentine setup, just harder to see.

 

Triple check the routing of the belt. It's very possible to have it routed wrong but "make sense" and have everything still work, just the tensioner can't get enough slack out of it. The correct routing isn't super intuitive.

I did just that a few years ago. Put the new belt on and got a bad alternator squeal (as identified by worsening whenever I turned on the headlights and/or blower.) Everything made sense; the ribbed and smooth sides were all on the right kinds of pulleys. But I had it routed wrong so it was far too loose. went back to the diagram and routed it the CORRECT way and the tensioner was significantly tighter.

EDIT:
Just realized I mis-read your post, and that the squeal was there before the belt change. As said above, careful use of a mechanic stethoscope is your best bet. they're a few bucks at harbor freight. Cleaning up the pulleys is also not a bad idea.

Though....you mention that the sound appears over 10mph? That sounds more like a powertrain issue. May want to see if you can get it up on a lift and "up to speed" to isolate where the sound is coming from. could be a bad wheel or driveshaft carrier bearing. maybe even the front diff needle bearing.

 

You can take the belt off a cold engine and run it without it in order to diagnose the issue. This is the easy way to eliminate the belt, pulleys, water pump...... You are not going to melt down a cold engine running it without the water pump for 10 seconds. If no noise, then go to the pulleys and accessories as said.

 

^^ This is the way

 

I had a weird squeal I could hear at speed. Did a new belt and decided at 140k miles ill do the idler pulleys. Noise is gone now.

 

*Edit*
So I took off my skid plate again and I’m watching the belt and pulleys while my truck is idling and I noticed that my tensioner has some play moving side to side , it’s the only thing moving none of the idler pulleys or other parts are moving except the tensioner . Is this normal or did I find the culprit ?

 

Usually see pulleys go bad before the tensioner, but its possible! If youre keeping the truck, replace the pulleys first, they are quite easy actually(and not too expensive), and see if it goes away. The tensioner is a bit of a pita to replace

 

If you are seeing play in the tensioner I'd be checking that the proper belt route was used like @risethewake said. It's an easy thing to get off and have it "look" right.