I'm posting this in sequence, as I have dealt with it over a couple months now. I've questioned folks on other forums, so I thought I'd see if anyone here has any insight. Hopefully you can follow along without getting confused.


So, it came back at almost exactly a year after it first happened. Last year about this time, I developed an awful chirping/squealing noise on my '97 Tahoe. I changed the idler pulley, tensioner, & serpentine belt with no change. I tried cleaning off all pulleys. Some said maybe the alternator, A/C compressor, water pump, or P/S pump. I pulled the alternator & cleaned it a bit while looking it over but noticed nothing abnormal. There is no coolant oozing from the w/p weep hole or anywhere. The pulleys all look to be in alignment. The A/C compressor was replaced in May this year, so I know it wasn't the culprit last year. The thing is it happens as soon as the outside temp drops. After temps warmed up this year, I never heard it the whole Spring/Summer. A couple weeks ago during our first temp drop, it popped up. The noise just gets louder as more load is put on the engine, but it quiets down as you sit at idle. Sometimes it will barely even be noticeable until you accelerate. Well, one day when our temps had warmed back up, I had gone outside to move it. I never heard the chirp. A few days later when it got cold again, it started chirping as soon as I turned over the key. Just so happened that the first cold snap this year was the same morning I took it in to test fit my new wheels. I had the mechanic at the shop take a look/listen, & he seemed to think it's the water pump pulley slipping. I have no idea, but I plan to have someone dig further into it. I wonder if it could be moisture-related? If so though, I have no idea how to stop it. It's just so annoying to drive like that!

The mechanic at the shop sprayed the pulley itself with something, but I can't remember if he tried spraying the belt. If I recall correctly, I think I tried that last year with no luck. However, I'll try again just in case I didn't. He did use a stethoscope to try and pinpoint. The conclusion he came to was the water pump pulley slippage. I'm not sure you can even replace those with anything other than used OEM or billet aftermarket? I know I didn't see new ones when looking at some of the parts stores online. I haven't had anyone else inspect it yet, but that's the plan once we get moved. If I get a chance this week, I'll see if I can catch it in action with some video. It's cold now, but temps should warm up again by week's end.

Update: So as I was getting ready to load the Tahoe onto the Uhaul trailer Friday, it started chirping as soon as I cranked it. It was probably upper 50's/low 60's that day. I had purposely left out some WD-40 to try spraying the belt. When I sprayed the top side (smooth) it didn't change. However, when I sprayed the bottom the noise changed. I sprayed more, & it eventually got quiet. However, the noise came back as soon as I put more load on the engine while moving it onto the trailer. So, what does that tell you guys (if anything)?

It had the top of the line Die Hard battery from Sears when I bought it, & I discovered some sort of stress crack on the very top. So, I had it warranty replaced late last year. It has a Goodyear Gatorback belt. It was on there when I bought it as well, & it still looks in good shape. I replaced it with a Dayco from Advance, & I made sure to research the correct part #. After installation though, the noise was still there & unchanged. I kept it on for maybe a month at the most & put the Goodyear back on. It was fine all Spring/Summer until that first cold snap. Maybe I should order a Gates belt & just try it?


Update:
Well, I decided to order a full Gates kit that includes the belt, idler pulley, & tensioner. It already had a new Gates tensioner & Dayco idler in the Fall last year. Instead of mix matching though, I figured I'd throw everything Gates on there since they tend to have a good reputation. We shall see if it makes any difference.

Well, I got the Gates idler pulley, tensioner, & new belt installed. I ended up cleaning the grooves of the pulleys again, & I noticed a bit of a squeak when spinning the alternator pulley. I wonder if that was my culprit all along. I lubed it good with some silicone spray until it quit making noise. After I got everything installed, I'm happy to say it fired up with no more annoying chirp/squeal. Monday afternoon I got ready to head to North MS to help with my dad. Well, I still didn't hear any noise. However, as I got closer to my hometown, slowing down in speed, I could hear a light chirp again. It progressively got more noticeable, but it's not quite as loud as it was in the past. I wonder if the lube on the alternator wore off, & maybe that is indeed my culprit.

I lubed the alternator again Thursday before leaving my dad's. I cranked it shortly afterward & still got the chirping. So I sprayed again & waited a while longer as I inflated the front tires. Cranked it again, but it was still chirping. I turned the vehicle around to inflate the rear tires, so I sprayed it yet again. Once I was done, it cranked with no chirping. Well, after I drove probably 30 miles or so & had to slow down in a city along the way, the chirp had returned. I didn't spray anything other than the alternator, so that has to be the problem. If that's the case, I guess I'll just go ahead & upgrade to a 140 amp, since I want to eventually add electric fans anyway.


Update:
Just received my new alternator yesterday. I went with the Powermaster 48206, which is a 165amp. Saved about $42 by having Summit beat another online price! It's the same style CS130D casing as my stock alternator, thus it should bolt right in. However, it was/is suggested that I upgrade the charge wire. I was told 4-gauge or larger to get the most potential out of the alternator. I'm not sure what gauge the factory charge wire is. Has anyone else done an alternator upgrade, & is there anything else I should consider doing at this time? Everything else is still stock for now, & it'll be a while before I install any power-suckers (E-fans, stereo system, etc.).

Well, my dad's friend Mark helped us last night with the alternator. We rounded up a 4-gauge cable & end links yesterday to make a new charge wire. Got everything installed and wired & fired it up. For about 2 -3 minutes it was quiet. Then that damn chirp came right back! Mark sprayed the back side of the belt as I had done before, & the noise temporarily stopped. It was right back within a minute. So, I'm still chasing this rabbit. Mark did spin the old alternator pulley, & it squeaked just as it did before when I tried it. But it wasn't the culprit. At least I have my alternator upgrade for future purposes, but I'm bummed that the chirping wasn't cured.

As worry free as serpentine setups are supposed to be, there are several things that can cause "chirping". Here is a link to the Gates trouble shooting pdf, great read. One thing most are not aware of is that the drive pulleys can wear out and not matter how many belts, tensioners, etc. you replace, the noise will always come back soon.
http://www.gates.com/~/media/education/ ... ension.pdf

Thanks for the link. I'll check it out. You're not the first to suggest a possible pulley issue. Isn't it odd that the chirping isn't an issue in warmer months though? I mean the past 2 years it happened right when the weather turned cold.

Temp can have strange effects on things.

So, we know how cold it was this past Wednesday. That afternoon, as I prepared to head to my dad's in MS, I went out to crank the Tahoe so it could warm up. Upon turning the key & engine firing, it made an abrupt whine similar to something you'd hear from a P/S pump. After a couple seconds, it went away. I haven't heard it anymore. It was also quiet for a couple minutes, but then the chirp returned.

Fast forward to yesterday (Friday) when I got ready to head back to TN. It fired up with no initial chirping. I waited a few minutes & still no noise. I drove down to the local gas station to fill up, & there was no chirping there & back. I then proceeded to drive 2.5 hours back home with no chirping whatsoever. It'll be back I know. Just a matter of time. If that don't make you want to shoot yourself, I don't know what will!

More than likely its the water pump pulley. I have seen it before. It either gets a good glaze on it from the belt or it gets grooved where its wearing from the belt. Just for GP you may take a brown roloc pad or green sanding disc on a die grinder and clean the glaze off where the belt rides and see if that helps. You can use emery cloth as well but takes longer if you dont have a die grinder. If its grooved or has any kind of lip where the belt rides than i would change the pulley.

Thanks for the input Terry. That's one road I have yet to cross but keep dwelling on. If you read through the whole thread, you probably saw where I mentioned a mechanic in SC saying he thought it was slippage at the water pump pulley. I was wondering how I could find a replacement since I didn't see them carried by any local parts store. I proceeded to research online & found them available through some of the GM discount parts retailers. One dealership I emailed also said he could get it, but it was cheaper online. I will just go ahead & order one. I do know that there's a bit of a lip where the belt rides, so that might indeed be the culprit.

Well, it wasn't the water pump pulley. I bought one last week & changed it yesterday. I didn't hear any noise upon start-up a couple times last night. Today while out driving it reappeared. It's not as noticeable, but it's still there. I bet as soon as the temp drops again, the noise will be just like before. Like I mentioned before, temp seems to affect it. That's probably why it's a bit quieter now, because the temps are considerably warmer. The last winter & this one has been the same chirping issue, but it never gave me an issue all last Spring/Summer. It started back during that first cold snap this past Fall & has continued since.

So annoying. Have you had a chance to read the Gates link?

Yes I did just after you posted it. I should've already had the alignment checked. That's actually my next step. I just need to find somebody to check it for me. Based on the info quoted below, I'd say there's a good chance that could be the problem (although I've said that with everything so far, lol). I've sprayed the back side of the belt before, & the noise will disappear temporarily.

"Another tip for identifying misalignment or slip is to spray
water on a noisy belt. If the noise gets louder, then the belt is
slipping due to loss of tension; if the water causes the noise
to fade or go away completely, then there is misalignment
in the ABDS."

Isn't it amazing how something so simple can be so complicated.

Yes it is. Guess I'll have to catch it on a bad day to have it inspected. That's what is frustrating and puzzling, because it isn't a constant. When I cranked it Friday to run errands with my dad, it was lightly chirping. It went away as we drove off, & I never heard it anymore while we were out. I later proceeded to drive 2.5 hours home with no issues. Temps were pretty darn cold that day too, so I was a little surprised to not hear it.

I'm happy to say that last Wednesday night we finally fixed the chirping issue. It feels so good to have that annoying sound gone. It had gotten so bad that I hated to even drive to town. A few weeks ago I went by a local custom shop in Spring Hill, & the guys there looked it over for a while. The only conclusion they could come to was that it might be the water pump itself. So, I gathered up a bunch of parts in preparation of a cooling system overhaul. I ended up going with the AC Delco OE style pump, which is pricey. However, they're supposed to be better quality. I also bought new Gates upper & lower radiator hoses, along with the small heater & bypass hoses that attach to the water pump. Since they were originals, I went ahead & replaced them all. I also bought a new Delco 195* thermostat & genuine GM serpentine belt just for the heck of it. Before installation, I bought some VHT satin black engine enamel & painted the pump. My dad's friend Mark did the work for me at a great deal. For what a local shop in Spring Hill was going to charge, it was a no-brainer to let him tackle it instead. I needed to make a trip down to MS anyway to help dad do some stuff at my grandparents' place, so it worked out good. Just wanted to update you guys, & I appreciate you all trying to help me diagnose it.

Well if it doesn't fix it at least you know you have a good pump. lol, Are the tensioners new?

It's fixed! Yeah, I went through two tensioners & idler pulleys, 3 belts, alternator, & water pump pulley trying to chase down that chirp. None of those cured it, which means they weren't faulty. Good to know, but I hate I wasted money on them. At least my alternator upgrade is good for future electric fan plans. The water pump was the culprit this whole time though. Oh well, just happy to have that chirping gone.

I'm sure you are! Always nice to have the little buggers cleared up.