4.0L belt squealing

So I replaced my belt about a year ago. It starting to squeal again. I'm wondering how bad of a problem this is? Only happens on startup and under hard acceleration.

 

Could be a pully or your belt tensioner

 

I replaced all pullies when I did the belt using koyo bearings, as I can recall. It hasn't even been a year. But should I be concerned it if only happens at startup and hard acceleration? Granted it could be the tensioner but that looks like a pain to replace.

 

Have you pulled the belt off and visually inspected it for damage? Even if it looks alright, there still may be damage to it. I just went through this about a week ago. The belt was squealing but looked perfectly fine when I pulled it off the truck. Swapped it with a new one and I haven't had a problem with the squealing since.

Is the belt OEM? Aftermarket?

 

The tensioner pulley can be replaced in-situ. Beware it's a LH-threaded bolt. Usually the tensioner pulley is the same P/N as the lower idler pulley.

Use either OEM or Bando-branded belt. Other brands can squeal.

 

Check pulleys and tensioner.. but keep in mind there's 2 kinds of Bando available. The OEM Bando is more expensive and will stay quiet. There's a cheapie Bando that sucks and will make noise within 3 weeks. Ask me how I know..

Gates makes a good belt. Some guys swear by Continental "gator-back" ..

 

^My experience with Gates in my Subaru was bad. Belt liked to slip on the power steering pump pulley no matter how hard I cranked the tension. Replaced with aftermarket Bando from Rock Auto and the slippage went away.

For the 4Runner, the Toyota OEM belt carries the same Bando P/N as the aftermarket Bando.

 

When I offroad more often I eat belts, dust, dirt, mud, all are bad for belts.

I had a busy offroad year 2020 and my belt only lasted one year. Bando belt.

 

Certain things make sense to price shop, but when it’s comes to Serpentine belts, timing belts/chains get OEM. Just the peace of mind and what are saving $20 buying an auto parts store belt. Not worth it IMO.

 

Yeah I'm running a Bando

$20 7PK2120 OEM Quality Serpentine Belt

7PK2120 which if you buy the OEM belt for the Tacoma V6, it will literally say Bando 7PK2120 on it. I've run both the OEM one and the one direct from Bando, they looked exactly the same and had no issues with either.

 

I recently had a problem similar to this. I had replaced y belt about two years ago and it had started to squeal on start up. I replaced it with a new belt and after a couple of days was having the same problem. I went to a friend who has been a mechanic for years to figure out why. He took one look and asked to see the routing diagram. I had accidentally gone underneath the pulley between the power steering pump and the water pump. He noticed that that pulley was not shiny like it should be. I had been running it like that for two years and when I put the new belt on I did the same thing. I was kind of embarrassed that I did not catch that.

 

The bearing in the pulley is replaceable if the pulley is in good condition. Last I checked, only Febest sold a pulley/bearing combination but it is a Chinese-made part. There are several Japanese-made bearings that can replace the oem bearing in the pulley. I have a thread with more detailed info.
https://www.tacomaworld.com/threads...arings-in-the-idler-tensioner-pulleys.480961/

Spray belt with water to see if the noise goes away temporarily - until the water dries out. If noise goes away, that tends to ID the belt as the source of the noise. First spray on one side of the belt, then the other. If no change in noise, a hearing is likely the culprit - this could be a pulley/tensioner bearing or the water pump, alternator or PS bearing.