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Discussion Starter #1
Hi, My '03 is chirping pretty good. All efforts to date have been unsuccessful in tracking it down. Any one here have a sucessful repair?

So far: Noise appears on startup, goes away after warmup.
The shop changed out the drive belt, probaby to Gates brand, sound disappeard for a week. I swapped out what appeared to be a bad idler pulley. The problem has not been corrected. Today, the shop mechanic swapped out the other idler pulley, examined the tensioner and other pulleys as well as the belt. Belt dressing eliminates the sound for ten seconds or so, then it would return (often louder). He couldn't isolate a bearing noise with a stethascope or otherwise diagnose it in 1.5 hours. A search through TSB's comes up with a) swap out the belt and B) swap out the belt to an alternate GM belt #.
I couldn't hang around for a delivery from the GM dealer, so I'll get the replacement belt myself.

Thanks for listenin'!
 

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is your a/c on when it is making the noise? Mine chirps when it kicks on and off. Maybe it isn't disengaging? Maybe an alternator?
 

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Discussion Starter #3
No, it's constant. There's no change when the A/C clutch engages. Your's sounds like the tensioner might be getting ready to depart the mortal plain:blowup Pulley misalignment seems likely to be the root cause, perhaps combined with an unforgiving OEM belt design.
 

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Let me know what comes of this, I recently (within the last week) noticed this also. Same exact symtoms. I have an '03 with about 90,000 miles
 

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I had the same problem, just changed the belt & it went away. I see you have already changed the belt though......you said belt dressing will stop the noise; how long was the belt that you changed to sitting on the shelf? Maybe the belt that you put on has been sitting on a shelf too long & is not as flexible as it should be.
 

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Discussion Starter #6
The mechanic ordered/installed it. from the look of his shop he doesn't stock parts so...? I still haven't got that alternate belt (mislaid the part no:)
 

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My 03 did the same thing. I did the belt dressing trick but it came back within 1 minute. Replaced the idler pulley with no change at all. Replaced the belt and the problem disappeard for about 3 months and know its starting back up again.
 

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I just got off the Alldata web site. This is what they state.

Diesel Engine - Chirp/Squeal On Cold Start Idle

Bulletin No.: 07-06-01-003

Date: March 07, 2007

TECHNICAL

Subject:
LBZ LB7 LLY 6.6L Duramax(R) Diesel Engine Accessory Drive Belt Chirp, Squeal, or Squeak Type Noise at Cold Start Idle (Replace Accessory Drive Belt)

Models:
2002-2007 Chevrolet Silverado (Classic)
2006-2007 Chevrolet Express
2003-2007 Chevrolet Kodiak C4500/C5500 Series
2002-2007 GMC Sierra (Classic)
2006-2007 GMC Savana
2003-2007 GMC TopKick C4500/C5500 Series

with 6.6L Duramax(R) Diesel Engine (VINs D, 1, 2 - RPOs LBZ, LB7, LLY)

Attention: Do not replace the accessory drive belt for a chirp noise during engine shutdown. This is a normal condition for a diesel engine.

Condition

Some customers may comment on an accessory drive belt chirp, squeal, or squeak type noise at idle, especially on a cold start. The noise may be reduced or go away after the engine warms up.

Correction

Refer to Service Bulletin Number 05-06-01-018A. Follow the service procedures outlined in the bulletin to diagnose and repair an accessory drive belt chirp, squeal, or squeak type noise at cold idle.

If the noise was not fully eliminated by the service procedures outlined in the bulletin in step 1, then replace the accessory drive belt with a second design belt that may be less prone to noise.
 

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Discussion Starter #9
excellent - that referenced bulletin 05-06-01-018A has the alternate belt parn number in it. Thanks rogerkoop!
 

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My dad has replaced the belt and belt tensioner twice now. The problem came back this morning. Maybe something needs to be done to alter the pulley assembly? Any help would be appreciated. Don't flame me just because I am a dodge guy either :p....I love all trucks :D
 

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Discussion Starter #11
The alternate serpentine GM belt is doing the job... time will tell. FWIW, it has a fairly light, crosshatched pattern on the backside. If it returns, I'll be looking at bringing the PS pulley or air pump into alignment with the others (if req'd).
 

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belt chirp

I have an 07 Classic with 18,000 + miles. Same chirp descrilbed here, it usually goes away after it has run for the better part of an hour. Kind of annoying but not sure it's bad enough to start replacing stuff. Anyone tried getting GM to warranty something like this?
 

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If I were you, I would go to the dealership and complain about the problem. They have to fix it if there is any warranty left on the truck. If they give you a hard time, take a test ride in a brand new truck and see if it does the same thing. You paid 40-50,000 for a truck, make GM stand behind it. My truck is no longer under warranty, so I just live with it until something goes out.
 

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chirp chirp chirpity chirp

mine sang like a bird, ried the dressing, it was good for 40 seconds, then replaced the belt with a goodyear gator back. she was quiet for about 200 miles then she started a little squeal here and there. I figured I could live with it. Last night the squel quit and apparently the pulley quit as well. So, this morning I have to run out, locate the pulley, and another goodyear belt, and do repairs in the parking I left her in. Still think the gatorback belt is a fix.:gearjamin
 

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I had this same belt chirp on my truck since day one of purchase. Dealer couldn't fix it.

Went with a goodyesr gatorback belt and it's been perfect since(about 5000 miles)
 

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All The Above

Well I have tried all the above, and still have loud belt noise. I guess I will live with it. Thank god for the radio..:mad:
 

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mybe this will helpCondition
Important: It should be noted that a chirp type noise on engine shutdown is normal for a diesel engine due to higher engine compression and the rapid stopping of the crankshaft. No repairs should be attempted for this condition.

Some customers may comment on an accessory drive belt chirp, squeal, or squeak type noise at idle, especially on a cold start. The noise may be reduced or go away after the engine warms up.

Cause
Some 2004/2005 Silverado or Sierra trucks, with a 6.6L LLY engine produced before June, 2004, may have an A/C compressor/power steering pump mounting bracket and power steering rear mounting bracket that are machined slightly out of specification, causing a misaligned power steering pump.

If the power steering pump is misaligned, it will force the accessory drive belt to run farther inboard on the fan pulley. When the belt leaves the fan pulley, the belt will not align properly to the crankshaft pulley grooves and create a chirp or squeak type noise at the point of interference.

Vehicles built after June 2004 will already have the new A/C compressor/power steering pump mounting bracket installed, but still may exhibit belt noise caused by the power steering pump rear mounting bracket.

Correction
Vehicles built prior to June 2004, replace the A/C compressor/power steering pump mounting bracket.

Vehicles built after June 2004, enlarge the rear power steering pump bracket bolt holes.

Follow the published service information (SI) diagnostics for drive belt chirping. The diagnostic chart for the drive belt chirping will ask to inspect for a misaligned accessory drive pulley.
Important: Remove the top section of the radiator shroud and TCM/cover to gain access to check alignment and measure the power steering pulley on the power steering pump shaft.

Verify that the power steering pulley is properly pressed onto the power steering pump shaft. Refer to SI for the power steering pulley replacement. If the pulley needs to be realigned on the power steering pump shaft, follow the published SI procedures for the power steering pulley replacement.



If the noise was not fully eliminated by the procedure in step 2, the power steering pulley may be adjusted with an allowable maximum variance of 1.0 mm (0.039 in) to the front from the flush position on the shaft to assist in eliminating any remaining belt noise. Refer to graphic illustration number 1 and number 2. Ensure that the power steering pump pulley illustration number 1 is flush against the power steering pump shaft illustration number 2, with an allowable variance of 1.0 mm (0.039 in).
If the noise was not fully eliminated by the procedure in step 3, and there are no other concerns found, follow the published SI diagnostics for drive belt chirping. Then, if the vehicle was built prior to June 2004 go to step 5. If the vehicle was built after June 2004, go to step 6.



Vehicles Built Prior to June 2004:
5.1. Replace the A/C compressor/power steering pump mounting bracket with P/N 97362175. Refer to graphic illustration number 1. Follow the published SI procedures for the Air Conditioning (A/C) Compressor and Power Steering Pump Mounting Bracket Replacement.

5.2. With the new A/C compressor/power steering pump mounting bracket installed, reposition the power steering pump to gain access to drill larger holes into the rear mounting bracket using a 14 mm (1/2") drill bit. Drilling the bolt holes larger will ensure proper alignment of the bracket when installing the bolts. Refer to graphic illustration number 2.

5.3. Install the power steering pump to the A/C compressor/power steering pump bracket. Refer to graphic illustration numbers 4, 2, and 1.


Important: Power steering pump front mounting bolts must always be tightened first to ensure correct pulley alignment.


5.4. Refer to graphic illustration number 4 and tighten the front power steering pump mounting bolts.

Tighten
Tighten the bolts to 50 N·m (37 lb ft).

5.5. Refer to graphic illustration number 2 and tighten the rear power steering bracket bolts.

Tighten
Tighten the bolts to 50 N·m (37 lb ft).





Vehicles Built After June 2004:
6.1. Remove the front and rear power steering bracket bolts from the A/C compressor/power steering pump bracket. Refer to graphic illustration numbers 4, 2, and 1.

6.2. Reposition the power steering pump to gain access to drill larger holes into the rear mounting bracket using a 14 mm (1/2 in) drill bit. Drilling the bolt holes larger will ensure proper alignment of the bracket when installing the bolts. Refer to graphic illustration number 2.

6.3. Install the power steering pump to A/C compressor/power steering pump bracket. Refer to graphic illustration numbers 4, 2, and 1.


Important: Power steering pump front mounting bolts must always be tightened first to ensure correct pulley alignment.


6.4. Refer to graphic illustration number 4 and tighten the front power steering pump mounting bolts.

Tighten
Tighten the bolts to 50 N·m (37 lb ft).

6.5. Refer to graphic illustration number 2 and tighten the rear bracket bolts.

Tighten
Tighten the bolts to 50 N·m (37 lb ft).

Dual Generator System
New belts are not available for dual generator systems. If a belt chirp noise is occurring on a dual generator system, please complete a Field Product Report (FPR). The instructions for completing a FPR can be found in Service Bulletin Number 02-00-89-002F.

Parts Information
Part Number
Description
Qty

97386417
Bracket, A/C Compressor and Power Steering Pump Mounting
1


Warranty Information
 

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Thanks

Wow..that was impressive. Thanks for the info. You are awsome. This is a huge help in eliminating an annoying problem. Thanks again for your help..
--Pottsie:drink
 

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Fixed for now

I tried the third and final belt today, a goodyear gator, and for the first time since owning the truck, I heard the turbo instead of belt screech. Yess! Now life is good. If the sound comes back, I will definatly be getting the new bracket for the power steering pump/pully. Thanks so much for all your help with this guys. It's really great.:rof:rof:rof
 

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My 02 lb7 does the same thing. It will sit there and squeel a little. The sound goes and comes when it pleases. I was just talking to a mechanic the other day about it and he told me that it had to do with the way the pulley is placed. I do believe he said to solve the problem the pulley needs to be adjusted in/out just a hair or two. He says the problem isnt the belt it how the belt runs on the pulley not wuit centered.
 
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