my 4runner has been making that horrible screaching sound when u first start it up, for like the first 15 seconds. it normally stops when u rev it up a little bit and it gets warmed up. well i thought it was a belt slippin and well its not. its either my alternator or my power steering. i know an alternator bearing overtime can cause that sound but will a power steerin pump do it. i need to know wut to replace but cant seem to figure out which one it is. is there anyway to tell. thanks for the help.
-Kyle

 

Ya have somebody stand there with your hood up while you start it and listen for the noise. It could be the clutch on your fan as well. Would be pretty easy to pinpoint I would think if you stuck your ear in there during a start. Also how did you rule out that it was a belt slipping? That's what is sure sounds like to me.

 

What engine?

If the belt is separate, like on the 22RE, you could remove the p/s belt and see if the noise goes away, if so it is that belt or the idler pulley or something on that belt loop. If not, it is the water pump or alternator.

 

the noise doens't really do it long enough to have someone really look for something, it just kinda does it, then it doesnt. its the 3.0. i ruled out a belt slipping because it used to do it bad every morning on the way to school and i just started putting a little oil behind the pulley on the alternator and the power steering pump and it stopped. i know my alternator is going bad but i dont know if that is the reason for the sound or not. main reason im trying to figure out which one it is, is because my dad was tired of hearing the sound and said he would pay to get it to stop.

 

Like Roger said remove either the power steering belt or the alternator belt and see if the noise stops. I can't remember which one is on the outside on the 3.0 but that would be the easiest one to remove.

 

if one of them is screaching then it would be the bearing right? couldnt i just take the belt off both of the pulleys, spin them and see which one spins freely without a noise and which one like get stopped up. if it didnt spin good then the bearing was bad and that would be the cause of my screaching. plz inform me if my thinking is right on this one.
-Kyle

 

Yes, that is a possibility and valid way of checking it out.

 

If you suspect a bearing problem, take off the belt and check the pulley for lateral play by pulling on the pulley side-to-side (as opposed to in-out!). If you can feel any amount of play, the bearing is worn. Check it in several orientations, like north-south, east-west, etc. (That clear what I mean? )

Also, you can easily check if it's the belt(s) by simply replacing it/them. Belts don't cost much if it ends up not being one of them so you won't be out a lot of money.

 

Like the other guys said (and you've probably figured out) it's most likely a bearing going bad. My 22re would sound the same way and I narrowed it to the idler pulley bearing. I also replaced the belt at the same time. The bearing seized up enough so that the belt was just spinning on the pulley without the pulley turning. It is such a lovely noise, isn't it? Like nails on a chalkboard. Good luck!

 

alright well i have determined that it is in fact the alternator screaching so i will be buying a new one. im not looking to spend bunch of money on a new one. i know i can get a stock one new/rebuilt for 200 bucks minus 80 core charge. is there a certain brand i should get or anything else i should take into consideration when choosing a new alternator. thanks guys.
-Kyle

 

I'd just get a remanufactured one from O'Reilly. They come with a lifetime warranty, and they're less pricey than a new one from Toyota.