Need a mechanic

[cjnspecial]

Got a 98 Chevy 1500 silverado w/ 350 motor. Problem is there is a friggin high pitched squeaking noise that keeps coming back that is driving me nuts. Here is a run down of what all has been done from 1st to most recent:
1. Crank pulley had a dent in it. Replaced with factory new pulley. (no change)
2. Idler pulley/ serpentine belt(off brand)(fixed for about 100 miles)
3. Tensioner pulley replaced.(no change)(quieter for about 50 miles)
4. Tensioner assembly replaced(with new pulley)/Serpentine belt(gates) (fixed for about 1500 miles).
5. Tonight...swapped out idler and tensioner pulleys with old ones. Absolutely no change....still squeaks the same.

I replaced the tensioner assembly and changed to a gates belt at the same time and it was perfect for about 1500 miles, at which point the swarm of mating crickets moved back into the engine bay. There is no abnormal wear on the belt and no oil/power steering fluid is on it at all. It is quiet if the motor is idling but if you give it the least amount of gas......it starts squeaking again. Putting a load on the power steering pump has no effect. What else can it be? Any help is greatly appreciated.

 

[spacemule]

Alternator? Water pump?

 

[Stihl051master]

The alternators go bad on those trucks quite frequently. If it was on its way out, it could be causing intermittent problems when it gets under a load.
Does the truck have A/C? If so maybe the compressor is bad. I had this happen on my 1990 Chevy. Anytime it would kick on it would squeal. The defrost also runs through the A/C system for drier air, so it would present a problem if the defrost was being used. Try pulling the plug on it or just making sure your A/C and defrost are both off.

Other than that just pull the belt off and double check all pulleys to be sure they are turning freely, there is no side to side play in any of them, and they are all running true so the belt is running true in them.

 

[Stihl051master]

Check your fan also. It's probably a clutch fan on there, and the clutch could be dirty or whipped out and maybe not engaging all the way causing the squeaking?

 

[Rookie1]

The alternators go bad on those trucks quite frequently. If it was on its way out, it could be causing intermittent problems when it gets under a load.
Does the truck have A/C? If so maybe the compressor is bad. I had this happen on my 1990 Chevy. Anytime it would kick on it would squeal. The defrost also runs through the A/C system for drier air, so it would present a problem if the defrost was being used. Try pulling the plug on it or just making sure your A/C and defrost are both off.

Other than that just pull the belt off and double check all pulleys to be sure they are turning freely, there is no side to side play in any of them, and they are all running true so the belt is running true in them.

:agree2:

 

[cjnspecial]

The alternators go bad on those trucks quite frequently. If it was on its way out, it could be causing intermittent problems when it gets under a load.
Does the truck have A/C? If so maybe the compressor is bad. I had this happen on my 1990 Chevy. Anytime it would kick on it would squeal. The defrost also runs through the A/C system for drier air, so it would present a problem if the defrost was being used. Try pulling the plug on it or just making sure your A/C and defrost are both off.

Other than that just pull the belt off and double check all pulleys to be sure they are turning freely, there is no side to side play in any of them, and they are all running true so the belt is running true in them.

Check your fan also. It's probably a clutch fan on there, and the clutch could be dirty or whipped out and maybe not engaging all the way causing the squeaking?

Thanks for the advise everyone. That about narrows it down to the fan clutch. I'll take it off to see if the squeaks go away and post up tonight.
The water pump and alternator turn freely, even when the truck is warmed up/lights on, etc. The A/C turns freely and it squeaks whether the A/C is on or not. None of the pulley's have any noticeable run out and the belt is running true.

 

[spacemule]

Any way you can post a recording of the sound?

 

[JohnL]

Old alternator on my s-10 made a noise like that. It still worked, I replaced it fearing that the bearing was getting ready to fail.

 

[wood4heat]

My '99 had a squeal that turned out to be a bad intake gasket, sort of. It was low on coolant because of a leak at the back of the manifold. Replaced the gasket, filled it up with fresh coolant and the squeal went away.

 

[sawinredneck]

Have you tried using a pry bar and holding it against the altenator etc. and to your ear to track the sound down?
A long extension or something can work like a stehoscope to help you isolate noises. Just a thought.

 

[wood4heat]

Have you tried using a pry bar and holding it against the altenator etc. and to your ear to track the sound down?
A long extension or something can work like a stehoscope to help you isolate noises. Just a thought.

A short piece of hose works as well. To get the most out of either method put an ear plug in whichever ear you're not using.

 

[2000ssm6]

Good advice so far. Check all your accesories and make sure their brackets and bolts are tight. The power steering bracket/pump could be loose and deflecting, same with AC...

Might want to give a GM/AC Delco belt a try or get the next size smaller belt to help with the tension.

 

[Peacock]

Does it make the noise with the belt off?

 

[ShoerFast]

Just a few TS tricks for isolating noises....

If you suspect the Alt. load down the alt by turning everything on, same with power steering run it against the stops to load the PS. Cycle the AC and you can carefully add tension to idler-pulleys to listen for a change.

Worst cold or hot? Speed can sometime give away a location.
(Bearings sometime seem to liquefy grease and lube better warm. Not that it will narrow it down, but can give you a better time to be listening, like right at a cold start-up, or if a component gets worst hot?)

Squirting some fluid just up from a pulley will sometime deaden the sound for a moment.
(Don't be afraid to squirt a lot of fluid, try different things, WD-40, Brake-Clean even window washer fluid will sometime deaden a sound for you.)

Take the belts off one by one and start after each one to isolate, more of an old school multi-belt trick, taking the serpentine belt off can allow you to hand rotate things for a feel, noise feels gritty a lot of times.

Visual inspection is not always everything, taking a wrench to everything to see if you can get a little more snug will give a noise source away.

There are items that should just be replaced regularly, like idler pulleys and belts, at the start of a problem, as much as we all hate shotgunning parts, it is a good time to while your under there.

A 12 pack of beer can go a long way to get a qualified mechanic to lend an ear, dealership mechanics see the same problem many times, there are always new noises, but asking for advice if anyone thinks for a second that they might be over there head (no one here) is a good way to avoid a huge problem.

 

[cjnspecial]

Well.... Took the fan clutch off and it still squeaked. Here is what I now know for certain...it is a belt chirp, not a bearing chirp. I can spray lubricant on the belt and it quiets it down for a minute or so. While I had it off I took the belt off again and checked everything over once more. The a/c pulley spins freely with no runout, same with the alternator and water pump. The power steering pump does not have any axial play but you can push or pull the pulley/shaft in or out a few 32's of an inch. That may be the problem, I'm going to tinker with it more tomorrow. Thanks for the help and I'll keep you all posted.

 

[JONSEREDFAN6069]

i know this sounds dumb, but did you check your harmonic ballancer? i had one start to seperate on my dirt track stock car once made kinda the same noise you are describing. you seem to have checked everything else but that.
who knows.

 

[blakey]

Could be the belt itself?

 

[Peacock]

Like 2000 mentioned I'd go to the GM dealer with your belt and just get one that is incrementally shorter.

 

[cjnspecial]

It's fixed.....but I don't know why or how. Truck was squeaking this morning when I left and when I got to work the squeak was less frequent and quieter. It continued to get quieter at lunch and when I got home this afternoon it was silent. I was worried the belt came off but it is intact and in great shape.

 

[spankrz]

It's fixed.....but I don't know why or how. Truck was squeaking this morning when I left and when I got to work the squeak was less frequent and quieter. It continued to get quieter at lunch and when I got home this afternoon it was silent. I was worried the belt came off but it is intact and in great shape.

just like a chainsaw.... they sometimes fix themselves