I didn't drive my 07 very much during 1st two weeks of Sept due to our visit from Gustave. Drove it last week and noticed "chirping" sound from engine - looked and saw pully on harmonic balancer wobbling..
Checked past threads, and learned this problem occurred on some early production 05's. Chevrolet issued a TSB, but no TSB on later cars. Took car to dealer last Friday - they confimed diagnosis, didn't have part in stock, ordered it so it would be ready Monday. Ordered wrong part, placed correct part on backorder, now supposed to be ready this coming Friday.

Bottom line - if you hear a chirping that sounds like the belt - check out the crankshaft pully - if it fails and moves forward on the shaft it could damage the p/s rack, or worse, if it drifts backward - the front main bearing seal - you don't want either!

If this becomes a common problem, we should make sure other OT'rs know to be on the lookout.

 

I thought the harmonic balancer was only a problem on some of the 2005s. Good information.

 

The same thing happened on my '99 C5. The dealer replaced it and it never happened again.

 

I thought the problem had been eliminated in later production runs, but if this becomes a common problem, then maybe not. My car was exactly 2yrs old the day I brought it in, with approximately 24,000 miles. I'm very easy on my baby, and other than this problem the car has been perfect.

 

There are two problems that have been experienced with the Harmonic Balancer (crank pulley). The TSB was for early cars (the first 11,000) where there wasn't sufficient torque applied to some of the pulley bolts during assembly. Some came loose, some came completely out. If the bolt is only loose the pulley wobbles first, belts chirp and then are thrown off. If it the bolt comes out the pulley comes of the crank and slams around the front of the engine.

The second problem is a failed rubber flexible coupling that is part of the harmonic balancer. That only causes the pulley to wobble and the main belt to chirp.

The fix for both is the same. Replace the harmonic balancer according to the TSB.

 

I have an 07 with 40,000 miles. It is chirping and the pulley is wobbly. I guess it's going to the dealer tomorrow morning.

Thanks for the info.

 

It is a potential problem for any LS series engine. Chevy decided to save 5 cents by not keying the dampener to the crank snout on this engine series. This allows inertia loads to unscrew the crank bolt. As a partial fix, Chevy requires a one time use tighten to yield bolt (240 ft-lbs instead of the 70 ft-lbs that was entirely satisfactory for 100 million previous generation small blocks with keyed dampeners), and after bad experiences with 2005s they added the bandaid of a diamond coated friction washer. That doesn't really solve the problem either, but probably costs more than the correct solution of a key.

Since keying the crank now in the traditional way would require removing the crank from the engine to cut a keyway, a different pinning arrangement can be used which can be done without disassembling the engine. What I did is called in the trade a "dutchman". This involves drilling a hole on the parting line between the dampener and the crank snout so that half the diameter of the hole is in the dampener hub, and half in the snout. Then a round pin is driven into the hole, securely locking the two parts together. There are also pinning kits that require a radial hole be drilled through the dampener hub and into the crank snout. Then a radial pin is driven in to lock the parts together. Either way works, but the dutchman method is stronger against shear forces.

The only drawback to doing the dutchman is you have to remove the radiator to drill the hole. But since I had to replace the broken radiator anyway (thanks to broken lower radiator supports, due to the too low car hitting the roadway, another horror story), that was no drawback in my case.

 

I had the same problem with my 07 at 400 miles. Dealer replaced the balancer but needed a special tool to properly aline the pully and belts. Took an extra few days to get it right. No problems since the fix.

 

i had the chirping sound but it doesn't seem like it's coming from the belt, more on the fuel rail cover side (lifters maybe?). checked for wobbling but seems normal, not a perfect revolution. i compared it to my other vehicle and seems like it's fine. hopefully won't have no problem in the long run. was the chirping mentioned coming from the belt itself?

 

One thing to consider is not all chirping will be caused by the balancer problem. In fact, many GM cars are kinda known for chirping serpentine belts when they get dirty.

I've used carb cleaner (carefully sprayed on the inside of the belt as the engine is running) to clean the dirt off. No more chirp!

 

When I had belt chirp on mine, it was due to the balancer being warped, but not loose. The service advisor said he has heard of a few instances of this and that they normally show up outside the warranty, even though it is a manufacturing defect. He said that's why GM will often do it under goodwill program. Since the balancer replacement alone is about a $1000 job at the dealer, definitely pays to get any belt problem checked out before it causes further damage.

 

If you're lucky it will be only a chirp. When that rubber coupling failed on mine, the balancer moved backwards and started eating into the oil pan and the timing chain cover. $2500 to replace everything. Note that my '05 was built after the diamond-studded washer fix, so the crank pulley bolt never came loose.

 

I know it's an old post but just had mine replaced, 07 with 34K. She just started squeeking and like everyone else I thought it was a belt and noticed the wobble in the pully. Thank goodness for warranty!

Go Gators!

 

That is a shame. That is nothing new. I've seen that problem on numerous old style small block Chevy's for decades. I've had to replace a few over the years because the balancer separated and ate into the timing chain cover. The harmonic balancer has an outer ring and an inner ring with a rubber ring in between and they separate.

Same design for 50 years.

You would think the dumfecks at GM would evolve.

 

My pulley just blew apart yesterday..luckily it moved forward and i could feel the grinding noise when breaking so i got home as i was only a mile away, how hard is it to replace the pulley?

 

involved here is the TSB for the repair.

TSB 05-06-01-001A (Feb 8, 2005)

Check Gages Light, Battery Voltage Low, Accessory Drive Belt Slipping or Missing (Install Washer from WPC and Crankshaft Balancer) #05-06-01-001A - (Feb 8, 2005)
Table 1: Warranty Parts Center Parts
Table 2: GMSPO Parts
Table 3: Part Request Form -- Warranty Parts Center
Check Gages Light, Battery Voltage Low, Accessory Drive Belt Slipping or Missing (Install Washer from WPC and Crankshaft Balancer)
2005 Chevrolet Corvette

with 6.0L Engine (VIN U - RPO LS2)

Built Prior to VIN Breakpoint 55111039
This bulletin is being revised to include VIN breakpoint and additional inspection information. Please discard Corporate Bulletin Number 05-06-01-001 (Section 6 -- Engine).
Condition
Some customers may comment on the Check Gages Light or the Battery Voltage Low indicator coming on. Additionally, some customers may comment on the accessory drive belt either slipping or being missing.
Cause
The crankshaft balancer bolt may have become loose.
Correction
Install a new crankshaft balancer pulley, washer and a new balancer pulley bolt using the following procedure:
Disconnect the negative battery cable at the battery.
Remove the air duct (6).
Remove the radiator support.
Remove the accessory drive belt.
Disconnect the generator.
Remove the generator bolts and generator.
Disconnect the steering intermediate shaft at the steering gear.
Install the lifting links to the engine (J 41798).
Install the fixture for lifting the engine (J 41803).
Hoist the vehicle.
Remove the front wheels.
Loosen the motor mounts.
Install the leaf spring fixture (J 33432-A).
Disconnect the tie rods (5) from the steering knuckle (4).
Disconnect the speed sensor.
Remove the lower ball joint nut and disconnect the lower control arm from the knuckle.
Disconnect the bottom shock absorber bolts.
Disconnect the ABS module bracket bolts.
Disconnect the stabilizer shaft insulator clamp bracket bolts and shaft.
Disconnect the cooler line bolts to the engine cradle.
Install a suitable jack under the cradle.
Remove the cradle nuts.
Lower the cradle.
Remove the A/C belt.
Disconnect and remove the starter.
Install the flywheel holding fixture J 42386-A.
Remove the cooling fan bolts and fan assembly.
Scribe or mark balancer orientation.
Remove the crankshaft balancer bolt (139). Do not discard the crankshaft balancer bolt. The balancer bolt will be used during the balancer installation procedure.
Use the J 41816 (1) and the J 41816-2 (2) in order to remove the crankshaft balancer.
Place the old and new balancers on the bench and orient them the same way (i.e. face up with a weight balance hole at 12 o'clock). Scribe/mark the new balancer in the same location as the old balancer. Do not transfer weight pins on manual transmission equipped vehicles. Most vehicles will be balanced without the use of any additional weight pins. Because some balancers may have spun on the crankshaft, transferring weight pins to the same position would produce a random imbalance. For vehicles that exhibit imbalance (very rare), contact Technical Assistance.
Inspect for the following conditions:
• Metal transfer to the crank post. Replace the crankshaft if metal has been transferred to it or it is damaged.

• Metal transfer or damage to the timing chain sprocket face. Replace the sprocket if either condition is present.

• Verify that the bolt does not bottom out in the crank post.
Install the new washer onto the crankshaft and push into place by hand.
Install the new balancer paying attention to line up the scribe mark.
Use the J 41665 in order to install the balancer.
Assemble the threaded rod, nut, washer and installer. Insert the smaller end of the installer into the front of the balancer.
Use a wrench and hold the hex end of the threaded rod.
Use a second wrench and rotate the installation tool nut clockwise until the balancer is started onto the crankshaft.
Remove the tool and reverse the installation tool. Position the larger end of the installer against the front of the balancer.
Use a wrench and hold the hex end of the threaded rod.
Use a second wrench and rotate the installation tool nut clockwise until the balancer is installed onto the crankshaft.
Remove the balancer installation tool.
Notice: Failure to apply proper torque to the old balancer bolt may result in the balancer not being fully seated. This could lead to failure of this joint in the future.
Install the old balancer bolt and tighten.
Tighten
Tighten the old balancer bolt to 330N•m(240 ft. lb).
Important: The nose of the crankshaft should be recessed 2.4-4.48 mm (0.094-0.176 in) into the balancer bore.






Remove the old bolt and measure the hub to crankshaft distance.
Coat the three to five threads of the new bolt with thread locker (LOCKTITE™ 272) P/N 12345493 before installation.
Notice: Be sure to follow the torque procedure for installing the new crankshaft bolt. Use of impact tools, or not using torque and angle method will result in joint failure.

Install and tighten the new crankshaft bolt.
• Tighten the crankshaft balancer bolt a first pass.

Tighten
Tighten the crankshaft balancer bolt a first pass to 50N•m (37 lb ft).

Put a paint stripe on the bolt running from the 12 o'clock to the 6 o'clock position in order to verify the correct torque requested in the next step.

• Important: When tightening for the second pass, a minimum torque of 320 N•m (236 lb ft) should be observed. If this torque is not achieved, the bolt should be replaced.


Tighten the crankshaft balancer bolt a second pass.

Tighten
Tighten the crankshaft balancer bolt a second pass to 140 degrees using the J 45059.

Important: Recheck the position of the previously painted stripe to assure 140 degree rotation. Achieving the correct torque angle is critical to the success of this repair. Over-torquing or under-torquing the joint will result in an unsatisfactory repair.
Remove the J 42386-A Flywheel Holding Tool.
Install the starter and bolts. Tighten the starter bolts.
Tighten
Tighten the starter bolts to 50 N•m (37 lb ft).

Important: Orient the purple lead wire to the 10 o'clock position when installing.
Connect the starter wiring.
Install the starter motor S terminal washer and purple lead wire (1).
Install the S terminal nut (2) and tighten.

Tighten
Tighten the S terminal nut to 4 N•m (35 lb in).

Important: Orient the gray and rust harness leads to the 6 o'clock and 7 o'clock position.


Install the gray and rust harness leads to the solenoid.
Raise and align the cradle.
Install and tighten the cradle nuts.

Tighten
Tighten the nuts, using hand tools only, to 110 N•m(81 lb ft).

Install and tighten the engine mount nuts.

Tighten
Tighten the nuts to 65 N•m(48 lb ft).

Install the A/C belt.
Install the cooler line bolts.
Install the fan shroud assembly and bolts.

Tighten
Tighten the bolts to 5 N•m(44 lb in).

Position the stabilizer shaft and install insulator clamps and bolts.

Tighten
Tighten the stabilizer shaft insulator clamp bolts to 58N•m (43 lb ft).

Install the tie rod to the steering knuckle.
Install the outer tie rod end stud nut to the outer tie rod end stud and tighten .

Tighten
Tighten the outer tie rod end stud nut to 20 N•m(15 lb ft) to seat the stud.

Turn the nut an additional 160 degrees.
Check for the outer tie rod end stud nut for a minimum final torque of 45 N•m(33 lb ft).
Install the lower ball joint to the steering knuckle.
Tighten the lower control arm ball joint stud nut.

Tighten
Tighten the nut to 20 N•m (15 lb ft) to seat the ball joint stud.

Turn the ball joint stud nut an additional 210 degrees.
Check the ball joint stud nut for a minimum final torque of 55 N•m (41 lb ft).
Install the shock bolts and tighten.

Tighten
Tighten the shock absorber lower mounting nuts to 28 N•m (21 lb ft).

Repeat tie rod, lower ball joint and shock for the other side.
Install the tires and lug nuts.
Important: Tighten the nuts evenly and alternately in order to avoid excessive run out of the tire and wheel assembly.
Using the J 39544-KIT , tighten the wheel nuts in the appropriate sequence shown.
Tighten
Tighten the nuts in sequence to 140 N•m(100 lb ft).

Remove the support jack.
Remove the Leaf Spring Compressor (J 33432-A).
Lower the vehicle.
Remove the engine support fixture.
Remove the engine support links.
Install the upper radiator support and tighten the bolts.

Tighten
Tighten the bolts to 9 N•m (80 lb in).

Install the coolant and EVAP lines to the fan shroud.
Install the engine cover and oil fill cap.
Install the intermediate shaft.
LOCTITE™ the steering intermediate shaft bolts and install.

Tighten
Tighten the lower coupling retaining bolt to 34 N•m (25 lb ft).

Install the generator and tighten the bolts.

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

Connect the generator wiring.

Tighten
Tighten the battery feed cable nut to 13 N•m(10 lb ft).

Install the new accessory belt.
Install the air duct and box.
Connect the battery cable to the battery.
Perform a crankshaft variation relearn procedure.
Parts Information
Order a washer from the WPC using the form at the end of this bulletin. Fax the request form to the WPC at 248-371-0192, or E-mail to warrantypartscenterusa@gm.com .

All other parts should be ordered from GMSPO. Use the normal ordering process for all orders.

Warranty Parts Center Parts WPC Part Number
Description
Qty

305
Washer, Crankshaft Balancer
1

GMSPO Parts Part Number
Description
Qty

12557840
Bolt, Crankshaft Harmonic Balancer
1

12583637
Balancer, Crankshaft Harmonic
1

12579229
Belt, Water Pump, Power Steering and Generator
1 as req'd

12579228
Belt, Air Conditioning Compressor
1 as req'd


Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
Description
Labor Time

J0710
Pulley, Crankshaft Balancer - Replace
2.3 hrs

 

Looks like I just squeek under the radar here with an '05 Vin of 55120011.

Thanks for the info. I will keep an eye on mine and if it becomes a problem, I will have a good excuse to upgrade to an aftermarket SFI approved balancer and ARP bolt.

 

Just started installing a supercharger an my next step was going to be pining the harmonic balancer. Well I remembered seeing a bit of a wobble right before I put it away for winter. So put the battery in an fired it up. Its a older vette not a c6 but a 2000 C5 with 60,000 miles on it . Gawd dam its a good thing this is just a winter project ! Should I go with a after market balancer. Its a A&A PS1 v3 kit I am installing . Bought hp tuner software as well. This far into it whats another Grand now ? ! # @

 

Does it chirp all of the time? Or just sometimes. I have a noise in my engine that sounds like it is coming from the front end of the engine that goes away after a few minutes when the car warms up. I checked the pulleys yesterday and I could not see that any of them were wobbling. The noise sounds more like a clicking noise than a chirping sound. But it sounds like plastic. It doesn't sound like a lifter or anything in the engine. I can't figure out what it really is. The last eight numbers on my vin is 55105300

 

Old thread.
The TSB above is overkill. There is a much more easy way to swap the HB. It's still quite involved and not for the faint of heart, but not extremely difficult...just time consuming as a lot of components have to be moved out of the way.

If you go through the hastle and expense of doing it, I wouldn't install another GM pulley. But install a Power Bond, SLP etc instead. PB has a stock 7.4" pulley as well if you don't want to reduce to an underdrive pulley.