chirping/squealing noise

[likaroc13]

My '97 Tahoe has developed a chirp/squeal type noise similar to that of an idler/tensioner/belt issue. It can sometimes be heard lightly at idle, however it's mainly when the engine is under load. In August I replaced the idler pulley & installed a new belt. That seemed to cure most everything, however I could still hear a light chirp. When I took it in for a differential fluid change about a week later, I had the mechanic listen. He noticed a lot of build-up on the tensioner, so he went ahead & replaced it for me. My issues seemed to disappear....until about a month or so ago. My wife and I drove to a relative's house one evening while it just happened to be raining. It started chirping & continued to progressively get worse as we drove. I thought maybe it was moisture, as it quit doing it on our way home. My wife also proceeded to tell me that it did this to her one day when she drove it to work, which I wasn't previously aware of. On a different day which was dry & sunny, it began to chirp again. Thus, I ruled out moisture. Well, I took it in for a brake fluid flush & asked the mechanic to take a quick listen. He said he felt some play in the idler & thought maybe it was a bad bearing. The following weekend, my wife and I took it to town. The chirping progressively got louder & worse as we continued to drive. Knowing what the mechanic mentioned, I decided I'd replace the idler while it was under warranty. I swapped it out, but the chirps continued. So, I switched back to the original Goodyear belt which was still in nice shape. That still didn't make a difference. While it was at a local classic restoration shop this week getting some detailing done, I had the owner take a listen. He initially told me it might be a bearing in the alternator, & we both agreed that it could possibly be the A/C compressor. However, they went around with a stethoscope & couldn't pinpoint the noise. It didn't seem to be either the compressor or alternator. On the 15-mile or so drive home, it was completely quiet 98% of the way. However, as I sat at the last intersection in congested traffic for at least 5 minutes, I began to hear the light chirp. As I then accelerated, it continued to chirp just as it had before.

At this point, I'm not sure. I could try the tensioner, but I'll have to buy a new one out of pocket. I don't have the receipt from when the shop replaced it. What else could it possibly be? The owner of the restoration shop thought it could possibly be the water pump. I will probably take it in for further checking when I get back from our Christmas vacation, but I wanted to see what you guys think. It's really annoying & makes me feel like I'm driving a clunker.

[speedygonzales]

Does it ever do it just idling in the driveway?

[likaroc13]

Originally Posted by speedygonzales

Does it ever do it just idling in the driveway?

That's in the second sentence of my explanation. The majority of the time, the answer is no. However, it will lightly chirp on occasion. It's very much more pronounced as you drive, both in noise produced & repetition of the chirps.

[buddy_1]

Could be a belt alignment issue. Look at the P/S pulley and make sure it is flush with the end of the pump shaft. I've seen some that had moved out a fraction of an inch and caused a noise. If that looks good, remove the belt and try to pull the pulley out of the pump. Seen a couple that the shaft had broken inside the pump and would come out at times.

[likaroc13]

Originally Posted by buddy_1

Could be a belt alignment issue. Look at the P/S pulley and make sure it is flush with the end of the pump shaft. I've seen some that had moved out a fraction of an inch and caused a noise. If that looks good, remove the belt and try to pull the pulley out of the pump. Seen a couple that the shaft had broken inside the pump and would come out at times.

Thanks for the info! I'll definitely check it out. My wife took it to work this past Wednesday, & she says it didn't squeak. I was outside when she pulled up & didn't hear anything either. She also drove it Thursday, & I clearly heard it squeaking/chirping when she got home that evening. I'll try to get it figured out when we get back home in a couple weeks.

[buddy_1]

Oh, I forgot to mention to check and make sure the water pump is not starting to leak. Check the weep hole for stains or drips and inside the pulley for coolant. With the way the drive belt runs around the front of the engine, it could be getting some coolant on it and causing a chirp also. That could explain the build up on the tensioner that previous tech found. Buddy

[likaroc13]

Originally Posted by buddy_1

Oh, I forgot to mention to check and make sure the water pump is not starting to leak. Check the weep hole for stains or drips and inside the pulley for coolant. With the way the drive belt runs around the front of the engine, it could be getting some coolant on it and causing a chirp also. That could explain the build up on the tensioner that previous tech found. Buddy

Thanks Buddy. Yeah, the owner of the restoration shop also mentioned that it could be the water pump on it's way out. Will be sure to check it out as well. Thanks again for your input.

[Pine Bark Auto]

Are there not 2 idler pulleys? One on the tensioner and a stationary, smooth one. I once replaced the tesioner pulley on my 03 and still had the "same but different noise". Went back and changed the second pulley and eliminated it. Also, didn't happen in my case, but a friend replaced the pulley and bearing only on his tensioner and still had a chirping noise. Turned out his noise was coming from the movement of the tensioner itself and he had to replace the entire assembly. You stated you replaced the tesioner though. Maybe try moving it with a wrench and see if you get a noise. One last suggestion. As another poster mentioned, water or coolant on the belt will make that noise. Check for a possible intermittent coolant leak from hoses, recovery tank, waterpump or intake.

[likaroc13]

Originally Posted by Pine Bark Auto

Are there not 2 idler pulleys? One on the tensioner and a stationary, smooth one. I once replaced the tesioner pulley on my 03 and still had the "same but different noise". Went back and changed the second pulley and eliminated it. Also, didn't happen in my case, but a friend replaced the pulley and bearing only on his tensioner and still had a chirping noise. Turned out his noise was coming from the movement of the tensioner itself and he had to replace the entire assembly. You stated you replaced the tesioner though. Maybe try moving it with a wrench and see if you get a noise. One last suggestion. As another poster mentioned, water or coolant on the belt will make that noise. Check for a possible intermittent coolant leak from hoses, recovery tank, waterpump or intake.

Thanks. Yeah, I need to double check that tensioner assembly. The whole unit was ineed replaced in August, shortly after I replaced the smooth idler pulley. I don't recall seeing any intake coolant leaks. The PO had the intake gaskets replaced when he had it, about 10k miles ago.

[mountie]

I chased a squeak..... thought it was nearly everything mentioned here....

Eventually, I found a broken bolt holding my smog pump..... it was a micro-off alignment, and caused the squeak.

Maybe check all your accessory bolts for a loose bolt? ( cracked/broken?)

[likaroc13]

Originally Posted by mountie

I chased a squeak..... thought it was nearly everything mentioned here....

Eventually, I found a broken bolt holding my smog pump..... it was a micro-off alignment, and caused the squeak.

Maybe check all your accessory bolts for a loose bolt? ( cracked/broken?)

Good idea as well. Thanks! I did retorque the idler thinking it might not be tight enough, but I didn't check other bolts. Would be awesome if I'm lucky enough to only have a minor bolt issue.

[Shyguy]

I had a similar noise and finally found it was coming from the distributor shaft. I pulled the distributor out and lubricated the shaft and never had another problem with the noise.

[Boog]

If you can catch it making the noise remove the drivebelt and start it to see if it's not a belt related issue. My nephew has an 08 pkup in his shop with an occasional chirp or squeak and was diagnosed with a flat cam lobe.

[likaroc13]

Originally Posted by Boog

If you can catch it making the noise remove the drivebelt and start it to see if it's not a belt related issue. My nephew has an 08 pkup in his shop with an occasional chirp or squeak and was diagnosed with a flat cam lobe.

Is that something that would just randomly pop up? I never had an issue in about 6k miles or so, & it wasn't an issue when I bought it. I haven't tried with no belt, but I did put a new belt on with no difference. I put the old belt back on (which was in good condition), & it's the same as with the new.

[buddy_1]

The cams will normally make the noise in neutral at 1500 to 2000 RPM steady rev.

[400sbctruck]

Hello, first post nice to meet you.

Ive had really poor luck out of most tensioner and idler pullies available.
Seems they are adequate, however use chinese bearings. Most bearings used there are sealed and non lubed.

Autozone, advance -niether has adequate parts if you are looking for quality.
Go with Gates brand, to my knowledge as of a few yrs back all bearings were federal mogul. Gates brand is in oreillys, napa, and carquest. Belts too.

I spent a long time in parts and many more years bolting them on.
Just what i would look for/ hope it helps.

[400sbctruck]

Also, you can use the tensioner tool with the engine running.
-no squeal, but squeals when u ADD tension, usually an old dried up bearing.
-no squeal, but starts when you BARELY REMOVE tension=weak tens spring.
Squeals but goes away when ADD-weak tensioner.
Squeals but goes away when you remove tension- bearing.

Fwiw gm used k060947, k060956, k060960, and k060966 belts. Which belt u have? Last three # on belt are length in cm. last number is a decimal. If u have k060956 for example, swap to k060950(think it fits volvo if I remember right) the aftermarket stuff (usually) performs better with shorter belt due to varying tensioner pre-load. Just one of countless useless data i hope proves useful.

That adequately checks the idler-tensioner systemand allows moving on. Next stop is the alternator/ it is stressed the most in off-idle situations and such
The cam in that engine should be a roller, lobe could be swedged/brinneled, you would likely have noticed click from it ticking after full lift on the closing side. 9 out of ten times, if you check the spring it will be weak if the lobe was the problem, unless for some reason you have a flat tappet cam(lets not mention oil and additives nless this is the case). Hope i helped.

[likaroc13]

Originally Posted by 400sbctruck

Hello, first post nice to meet you.

Ive had really poor luck out of most tensioner and idler pullies available.
Seems they are adequate, however use chinese bearings. Most bearings used there are sealed and non lubed.

Autozone, advance -niether has adequate parts if you are looking for quality.
Go with Gates brand, to my knowledge as of a few yrs back all bearings were federal mogul. Gates brand is in oreillys, napa, and carquest. Belts too.

I spent a long time in parts and many more years bolting them on.
Just what i would look for/ hope it helps.

Originally Posted by 400sbctruck

Also, you can use the tensioner tool with the engine running.
-no squeal, but squeals when u ADD tension, usually an old dried up bearing.
-no squeal, but starts when you BARELY REMOVE tension=weak tens spring.
Squeals but goes away when ADD-weak tensioner.
Squeals but goes away when you remove tension- bearing.

Fwiw gm used k060947, k060956, k060960, and k060966 belts. Which belt u have? Last three # on belt are length in cm. last number is a decimal. If u have k060956 for example, swap to k060950(think it fits volvo if I remember right) the aftermarket stuff (usually) performs better with shorter belt due to varying tensioner pre-load. Just one of countless useless data i hope proves useful.

That adequately checks the idler-tensioner systemand allows moving on. Next stop is the alternator/ it is stressed the most in off-idle situations and such
The cam in that engine should be a roller, lobe could be swedged/brinneled, you would likely have noticed click from it ticking after full lift on the closing side. 9 out of ten times, if you check the spring it will be weak if the lobe was the problem, unless for some reason you have a flat tappet cam(lets not mention oil and additives nless this is the case). Hope i helped.

Thanks for the info! The tensioner actually came from O'reilly, because that's who the shop partnered with. But I'm not sure what brand it is since I didn't get a receipt. I'll do your suggested test though. The new Dayco belt is part #5060960, but I'm not sure if the old (but good) Gatorback belt corresponds to that exact same number. It squeaks/chirps with either belt though. The cam is still factory roller.

Btw, I'm originally from Corinth, MS, just down the road from you.

[400sbctruck]

Is it the 1997 in ur sig? At the counter, i would instinctively hand you a k060956 being a 97. The difference is in which pulley you have, 96 and early 97 was larger.
Parts application being what it is, you can go +/- a size usually. Seeing that u have aftermarket tensioner, the springs are stronger with different preload, and succeptible to "under tension" if longer belt used. Loosen the tensioner and see how much slack is there when pulling the belt tight by hand.
It would be great for that to be the problem vs the alternative!
Fwiw mine was k060947, but on 400sbc. Aftermarket pulley required k060950.

Also, the rollers are tough. Most any failure in that area suggests debris/other failure etc if thats the case i would advise teardown inspection and cleaning block. Heck some of them are what, 280-300k miles and no probs...

Ps, i built the washtown in iuca a few yrs back. Been thru your town often. Eagles nest and the wierd biker bar were usual stops when I hustled pool.

[likaroc13]

Originally Posted by 400sbctruck

Is it the 1997 in ur sig? At the counter, i would instinctively hand you a k060956 being a 97. The difference is in which pulley you have, 96 and early 97 was larger.
Parts application being what it is, you can go +/- a size usually. Seeing that u have aftermarket tensioner, the springs are stronger with different preload, and succeptible to "under tension" if longer belt used. Loosen the tensioner and see how much slack is there when pulling the belt tight by hand.
It would be great for that to be the problem vs the alternative!
Fwiw mine was k060947, but on 400sbc. Aftermarket pulley required k060950.

Also, the rollers are tough. Most any failure in that area suggests debris/other failure etc if thats the case i would advise teardown inspection and cleaning block. Heck some of them are what, 280-300k miles and no probs...

Ps, i built the washtown in iuca a few yrs back. Been thru your town often. Eagles nest and the wierd biker bar were usual stops when I hustled pool.

Yes, it's the 97 Tahoe mentioned in my Sig. Everything I've found points to me having the correct belt part #, however the tensioner & idler are both aftermarket now. As you said, that might make a bit of difference. It doesn't really explain why the chirping stopped for about 3 months though. It was beginning to chirp before any of that was replaced in August. It had gone almost 7 months with no issues prior to that. I now wonder if any of those original parts were faulty in the first place. I'm thinking it might be related to something else. I'll be home late Wednesday & start checking things out on Thursday if the weather permits.

[likaroc13]

Little Update: I'm still confused!

On Thursday I went out to crank it before making a trip to the store. This was my first time driving it in 2 weeks. It had already been raining earlier that day & was lightly misting when I popped the hood. I noticed the pulleys & belt to be coated with moisture. The rain is obviously splattering inside the engine compartment, but I'm not sure what I can do to seal it off. I wiped things down as best as I could & started the engine. It didn't squeak immediately but started shortly afterward. It was just the occasional chirp that it does when at idle. I tried to check the tensioner by lightly placing pressure on it. It seemed to slightly change noise as I added tension, but I can't swear to it. I didn't have much time to investigate as the rain was beginning to pick up. I went ahead & drove to the store, & the chirps/squeals intensified as they had in the past. It did this on the way to the store & back home. I figured I could chalk it up to moisture being the main culprit, but I dunno.

Well, Friday I looked it over really good for leaks. I couldn't find coolant anywhere, even after letting the engine warm up. All pulleys look to be in correct alignment, & it's still running the old Gatorback belt. It never chirped after cranking/idling, so I decided to make a trip up the road. Nothing! It never made a noise during the entire trip. So, today I went out to install my new LED interior bulbs. I cranked it while out there & still nothing. My wife decided she wanted pizza for dinner, so I figured I'd take the Tahoe to pick it up. The whole way it was quiet as a mouse!

Needless to say, I'm still not sure what the issue is. Before we left for our Christmas break, it had been routinely chirping for about a month & a half. This occurred at both warm & cooler temps, as well as during wet or dry conditions. I'm just waiting for it to make noise again before I investigate further. I thought for sure it would chirp either yesterday or today.

[400sbctruck]

Wicked little pest, gotta be simple.
Are your underhood splash guards all there?
Do you have a trace on the radiator cap seal from steam maybe?
A space heater would help rule out moisture as problem I guess, if it had a couple of hours of good heat and dry.


(just where my mind meandered)
So adding tension, was it worse? Kinda get a rush doing that...

[likaroc13]

Originally Posted by 400sbctruck

Wicked little pest, gotta be simple.
Are your underhood splash guards all there?
Do you have a trace on the radiator cap seal from steam maybe?
A space heater would help rule out moisture as problem I guess, if it had a couple of hours of good heat and dry.


(just where my mind meandered)
So adding tension, was it worse? Kinda get a rush doing that...

I haven't messed with it in the last couple days. Cold front coming through tomorrow, so I'll probably wait till Wednesday to check it again. I have a cowl induction hood, which was installed when I bought it. I'm not sure what all splash guard's it would have from factory. It does have the inner fender splash guards. The pics of my old '93 look to be pretty much the same under the hood, aside from the insulator which I don't have on the Tahoe.

As for tension, I can't really say for sure. I'm waiting on the chirping to begin again so I can investigate further. With the rain the other day, I didn't have much time to determine anything. I lightly added & released tension as it was chirping. It kinda seemed to change noise as I lightly added tension, but I could be mistaken. It might've just gotten quieter at that moment, as the chirps aren't constant when it's at idle.

[likaroc13]

So, I drove it again yesterday with no chirping. I took my wife to work this morning, & again no chirping there or back. I was about ready to write it off as having disappeared. Not so fast! This afternoon I made a stop at a local body shop before picking my wife up from work. As soon as I pulled up I could hear light chirping. When I left the shop, the chirping began to increase. After arriving at my wife's workplace, I popped the hood to look it over. I still can't decipher where it's coming from. I was planning to start digging further into it this evening, until it completely quit chirping about half way home. Unless I just start throwing parts at it (which I don't wanna do), I can't try to diagnose anything without it chirping. Grrrrrr!

[Rod_Lei]

My motto with my truck, while probably a bad one, wait until it just breaks.
Then you'll know what was chirping.
Last time I had a ghost chirp it was my alternator.