High-pitched squeal from engine

My 2000 Montana has just developed a squeal when the engine is cold. It seems to go away once the engine warms up. Of course, it's really cold here in Ohio right now, so I'm not sure whether this is a "big deal" or not.

I'm pretty sure it is coming from something driven by the serpentine belt. The squeal pitch rises and falls with the engine RPMs.

Turning the A/C on and off (or defrost) doesn't change anything.

I checked the power steering fluid, and it seems like it's full.

The water pump and serpentine belt were changed about 30,000 miles ago. The alternator, power steering pump, idler pulley and A/C compressor are original. The van has 122,000 miles on it.

I'm taking a ten-hour-round-trip drive this weekend, and I don't want something to fail on me. I'm worried about something like the alternator or water pump.

Any ideas as to how to isolate where the squeal is from? It's so loud and everything is so tight I can't determine where it's coming from by just looking and listening.

Take a close look at the belt tensioner and pulley, as well as certain model years also had and idler pulley. Sounds like a bearing failling. The tensioner problem can be identified by grabbing the the tensioner pulley out on the end and try moving it in and out. These have a habit of seperating with age and some times is visibly mis-aligned just looking at the tensioner. If these quick checks dont yield any results, remove the belt and spin all the accessory pullies (altenator, water pump, alternator, idler) checking for resistance or "roughness". Goods luck and have a safe trip

I'm feeling a little bit better about this. The temps are in the twenties today, and I topped off the Power Steering Fluid (it wasn't down to the add line, but it was at the "cold" line when it was warm) and started the van. I didn't get the squeal at all.

I cycled the A/C on and off and still didn't get a squeal.

It might have been one of those "really cold" gremlins that pop out when the temps are in the single digits. Or, it might have been that the Power Steering Fluid was just a tiny bit low.

I'm sorry to say that the noise started again. I took the van to a mechanic, because I can't determine where the sound is coming from.

I tried to jiggle all the pullies and everything seems as tight as can be. I don't have a lot of time, so I decided to let an "expert" diagnose the problem.

Evidently, I'm not as dumb as I think I am. They couldn't determine the location of the problem either. It doesn't help that the sound goes away as soon as the engine starts to get warm. They finally decided that it must be the serpentine belt (a Goodyear gator) that was installed only 30,000 miles ago. The mechanic didn't seem to be a fan of the belt, and he said there were some small cracks.

So, after nearly 100 bucks for time and the belt, I drove out of the mechanic's parking lot and didn't go 100 feet before it started squealing again. I turned around and went back, but by the time I got there, it had already quieted down. He came out with his stethoscope thingy and tried to see if he could hear anything unusual from any of the pullies, but everything was perfectly normal.

There's a part of me that wants to just replace all the idler and tensioner pullies, but that might cost more than I realize. After all, they have 122,000 miles on them. Couldn't hurt...might help.

Now, I'm faced with ten hours of driving this weekend, and I'm not sure I can trust the van. We might be renting just to be safe.

I replaced the tensioner (~$40) at around 135,000, the pully was toased and it locked up. It was an easy one bolt replacement. A year later, the idler pullys (~$16 each) were both replaced as well as the water pump (~$27)when mine started to squeal last. Turned out to be the harmonic balancer was going out. The squeal went away but it was then that I noticed the belt was half on/half off the HB. Might want to try the easier ones and if your able, the HB (I farmed this out, around $220 repair). It is the hardest to replace and most expensive part of the abovementioned items.

Well, I just went ahead and ordered the tensioner and idler pulley from Rockauto.com.

We're renting a van for the weekend.

Next week, when I get the new stuff, I'll put it on and see what happens. After all, with 122,000 miles on the van and plans to keep it for a while, the new stuff can't hurt anything. Plus, it's pretty easy stuff to replace.

I hope it isn't the harmonic balancer.

At least I'll know (if the squeal returns) that it isn't the idler pulley or tensioner. I can rule those out.

...
I hope it isn't the harmonic balancer...
..waiting for an update...but I do not think, until informed of the contrary, the harmonic balancer to be a common issue with the 3.4, this engine being a true 60° and quite naturally balanced...so there is not much of parasitic momentum to balance out and the harmonic balancer is rather solicited only mildly; the 90° 3.8 was really tough on balancers, even if the pistons were offset +/- 15° on each throw to even out the firing, in addition to the countershaft balancer. Tensioner bearing (..and there is also an idle on this one ?..) would be a good bet.
...alternator bearing can do a lot of whine too....and you did rule out the free wheeling A/C bearing by turning it on an off...(would stop squeeling when a/c compressor is ON...if outside temperature is warm enough not to disable it)

..waiting for an update...but I do not think the harmonic balancer is an issue with the 3.4, this engine being a true 60° and quite naturally balanced...so there is not much of parasitic momentum to balance out; the 90° 3.8 was tough on balancers, even if the pistons were offset +/- 15° on each throw to even out the firing, in addition to the countershaft balancer.

Naturally balanced...

Parasitic momentum....

Countershaft balancer....

I don't even know what to say about such intellectual terminology; however, my harmonic balancer did bite the dust at around 150,000 miles. Hopefully hufhouse has better luck than I did.

Did they say anything about possibly the water pump?

... my harmonic balancer did bite the dust at around 150,000 miles. .
http://www.avigex.ca/xport/balancerjunkphoto.jpg
this one from a 3.8; it really seems vibration took a toll. Can you remember if the damage on yours had that kind of signature ?

I don't know what it looked like, I farmed this job out to the mechanic. My serpentine belt would ride half on half off of it indicating the alignment was off and I was sick of messing with it. I did replace the water pump and both idler pulleys before this, didn't make any difference, then I noticed the serp belt misalignment.

The water pump isn't weeping, and it only has about 30,000 miles on it.

They inspected everything, and nothing seemed to be loose or hard to turn.

I'm still waiting on the idler and tensioner pullies to be delivered. I should have time to put them in some evening this week.

I received the parts that I ordered today from Rockauto.com and installed them this evening. (I didn't notice, and Rockauto didn't mention that there are actually TWO idler pulleys. I only bought ONE.)

I took the new belt off, and spun the pulleys one-by-one. I immediately noticed that one of the two tensioner pulleys did not spin as freely as the other one. I removed it first and replaced it with the new one. Once I took it off, I noted that it was very black inside and spun with a clicking noise, almost like there was a gear inside. Obviously, that's not right.

I then removed the tensioner and pulley and replaced that with the new one. The old one spun very freely, but I figured it was a pretty important part and it couldn't hurt to have a nice new one on there.

After growing a third arm from the middle of my forehead (oh wait, that's what I was wishing I had), I replaced the serpentine belt.

I started the engine, and it purred smoothly. However, this isn't really an accurate test because the engine was still slightly warm from a trip my wife had taken an hour or two earlier. We'll have to let it get really cold and see if that makes a difference.

I don't think I'm going to replace the other idler pulley because it spun very smoothly. (If it ain't broke, don't fix it.)

Right now, I'm feeling pretty good that one of the idler pulleys was causing the problem.

I'll let you know what happens after a few days.

Thanks for the help and information so far.

(By the way, I looked closely at the harmonic balancer from above and it looked to be in good shape and lined up well.)

I drove the van three times today from a cold start (once after sitting out in nine degrees all evening).

No squeal.

I'm 99.9% sure it was the idler pulley, which was obviously bad as soon as I gave it a spin. I'm really disappointed with the mechanic who looked at it last week. Almost $100 down the drain.

But you found the problem, it sounds like. Mechanic would have charge you even more if he had to track more stuff down, and you have a few items changed out so you are good to go. When my harmonic balancer went the mechanic first just replaced the belt, and it was quiet for a bit. Felt stupid cause I could have done that, but when the squeal came back and the HB was out of line, I didn't feel so bad.

I found it easier when putting the serpentine belt back on to put around all appropriate pulleys except the water pump. When you pull the tension off with one arm, push the belt under the water pump pulley with the other. Eliminates the need for that third arm!

....just in case...
http://www.likecool.com/Third_Arm--Other--Gear.html