High pitched screeching/squealing sound

[Blastingaston]

This is my first post here, I've been looking around and have found similar threads but none have really touched on the specifics that I'm having trouble with.

I have a 95 ford explorer. My problem is I am having a very high pitched screeching/squealing sound coming from somewhere under my hood. My only hypothesis is that it's the power steering. I have had problems with a power steering leak.

Let me explain. The noise only starts when it is cold, below 50 or 40. I don't know how else to describe it other than a very high pitched screeching/squealing sound that can become very loud. It was at its worst today when I was sitting in line at McDonald's. The Temperature outside is in the 30s. I was sitting completely still, just idling and it was squealing so loud. I wasn't turning the wheel at all, which is what really makes me question whether or not it could be the power steering.

Anyone have any ideas? Any feedback would be appreciated.

 

[arco777]

Take the serpentine belt off and spin everything by hand. Look for anything that feels tight, crunchy or way too loose. Chances are you probably have an idler bearing going out, or the alternator bearing. It is usually either the idler pully or tensioner pulley. On the 4.0 OHV they are usually the same pulley so if the tensioner pulley bearing fails, you can just buy a new idler pulley and install it on the tensioner instead of buying a whole new tensioner.

 

[Blastingaston]

Thanks for the info I will give that a try. After driving a little more the noise does seem to be related to acceleration. My dad seems sure that it's the power steering pump, but I don't think so. I have a little doubt in his knowledge.

My question is, how could it be the power steering when the power steering works fine? I have had some issues with a leak, but other than that I've had no problems. It does take a minute to loosen up on a cold day but that seems normal.

Does anyone see any reason to believe it could the power steering?

 

[Turdle]

Before everyone gets to
"speculating" you should be doing what was already suggested. Take the belt off and turn all the pulleys, by hand. They should all be silky smooth.

Once the serpentine belt is off, start the engine for a brief time to see if the noise is in the engine or the accessory drive. If the squeak is still there with the belt removed, you need to look at the cam sensor.

It will not hurt to run the engine for a few seconds with the belt removed.

Before removing the belt, make a small mark toward the front of the belt, when you re install the belt put the mark toward the rear. This will change the belt direction, and possibly quieten it down.
If this eliminates the squeak, you should replace the belt.

 

[Blastingaston]

I am going to give that a try as soon as I get off of work.

I'm a little confused when you say to put a mark at the front of the belt. I don't know much about cars so excuse me if I sounds foolish, but aren't the pulleys going to turn the same direction not matter how I put the belt on? I'm also not sure about where the front of the belt is. Relative to its position on the pulleys? Or the passenger side of the belt? considering if you're looking under the hood that would be the left side.

 

[Turdle]

Yes, the pulleys will still rotate in the same direction, however, the belt will be "pulling" from the opposite direction, if it is flipped. I suggested marking the front so you would be able to know it was flipped, by putting the mark in the rear when installing it.

 

[Blastingaston]

I think I see what you're saying. So I would mark the left side of the belt and when I put it back on, make sure that mark is on the left side? Or do you mean top and bottom?

I know I must sound really dumb but I'm just not seeing how the belt would pull any differently. I am going to try it, though.

 

[Turdle]

Front=front bumper
Rear=rear bumper.

Driver side=left
passenger side=right


Put a small mark ( 1/4 way across the belt) on the belt near the radiator (toward front bumper). when re installing the belt, make sure the mark is toward the engine (toward rear bumper).

 

[Blastingaston]

So basically, I'm taking the belt off and flipping it upside down?

 

[Turdle]

Yes.
However, you are going to be doing a bunch of stuff with the belt off, then forget how it goes back on. That is why you want to have a reference mark.

 

[Blastingaston]

Ya I see what you're saying. I am definitely going to give that a try. That's what I was thinking all along, I just didn't see how that would cause it to "pull" any differently.

Now that the temperature outside has risen above 40 I have not heard the noise, so far.

 

[Blastingaston]

So I did all of the above. Took the belt off, spun all the pulleys. Try spun what seemed to be just fine, except the power steering pulley and crank shaft pulley. The power steering pulley doe spin, just not as fast or as smoothly as the other pulley. I couldn't get the crank shaft pulley to spin at all. What's the verdict on those things?

After I took the belt off I ran the car for a minute and the noise was not there.

When I put the belt back on I flipped it as I was told, after driving the car after all of this, the noise continues.

 

[DjDom]

Lol, of course the crankshaft won't spin by hand. You've got compression in the cylinders, you can't turn it that easy. You can turn it with a breaker bar/torque wrench, but there's no point..
Seems like you've found which pulley is rough. Sometimes you can even hear if it's rough, it'll have a grinding sound inside.

 

[Blastingaston]

So I'm thinking about replacing the idler puller since that seems to be where the noise is coming from and it seems to be pretty inexpensive. All I need is a new pulley and I would just simply take the old one off and use the same old hardware to put the new one on?

 

[DjDom]

http://www.youtube.com/watch?v=vZirj_rbl7o

 

[Blastingaston]

Thanks for the link

 

[arco777]

So I'm thinking about replacing the idler puller since that seems to be where the noise is coming from and it seems to be pretty inexpensive. All I need is a new pulley and I would just simply take the old one off and use the same old hardware to put the new one on?

That's exactly right.

When you buy the new pulley, they may give you a slightly different one. Some have fences (lips) to keep the belt centered, some don't. Some are plastic and some are steel. All work fine, just don't install a ribbed pulley in place of a smooth one. Sometimes the new pulleys come with new bolts. Use your best judgement on which bolt to install. Factory is usually best but on some aftermarket pulleys it may cause the bearing to bind. Take your time.