Strange Sound From Manual Transmission Clutch

Well, Dave, you do need a second opinion. If you're the type of guy that is

*overly* concerned about the noise, then you need some satisfaction. First, if you are hearing "gears whirring" you would hear them all the time that the engine is running. The noise you described can be caused by a number of things that all relate to the clutch. The first thing most people would claim as the noisemaker is the throw out bearing. Its pretty common for them to make noise when they start to dry out. Its not real common for them to go so soon. You should probably hear the noise in any gear as the clutch starts to engage, but in forward and reverse, there is a transfer of power involved that may lessen the sound. Consider your dealer. The service manager heard it and said it sounded strange. If you take it back, you might get the same runaround. I'd suggest a second dealer if its not a problem. A new set of ears might confirm your suspicions.

As my clutch is released, the engagement point is reached about 1/2 way up. The noise is heard (I'd guess) about 90% of the way up, that is past the clutch engagement point. The clutch seems to be engaged at the "noise" point. I probably hear the noise in all gears, even when I leave a stop sign. However, a diesel is not the quietest of engines & probably masks the noise when actually driving. The noise is not heard at any point in the clutch travel except at this "90% noise point". The symptoms occur exactly the same whether or not things are warmed up (driven a bit).

An interesting point is that when I first brought the truck to the dealer, the service manager agreed there was a noise & it probably was the throw-out bearing. However, when I brought the truck back for the repair appointment, the mechanic said no problem.

I plan on taking the truck to another dealer as soon as I can. Since the other dealer sells the same make/model truck, warranty repair at a different dealer should not be a problem.

Not enought Fluid in the Transmission..

Dave wrote:

Excessive Shifter and/or Engine Vibration, Bearing Growl and/or Rattle Type Noise While Depressing or Releasing Clutch Pedal (Replace Flywheel and Flywheel Mounting Bolts) #04-07-31-006A - (Dec 9, 2004) Excessive Shifter and/or Engine Vibration, Bearing Growl and/or Rattle Type Noise While Depressing or Releasing Clutch Pedal (Replace Flywheel and Flywheel Mounting Bolts)

2001-2005 Chevrolet Silverado

2001-2005 GMC Sierra

with 6.6L DuramaxT Diesel (RPOs LB7, LLY) and Manual Transmission (RPO ML6)

This bulletin is being revised to add the 2005 model year, VIN breakpoints and include the replacement of the eight flywheel mounting bolts. Please discard Corporate Bulletin Number 04-07-31-006 (Section 07 -- Transmission/Transaxle).

Built Prior to the following VIN Breakpoints:

Plant VIN Breakpoint

Flint, MI 5F836256

Pontiac, MI 5E148789

Condition Some customers may comment on a bearing growl or rattle-type noise while depressing or releasing the clutch pedal. Some customers may comment on excessive shifter or engine vibration. In some cases, the excessive vibration may result in an injector balance rate fluctuation condition.

Cause The steel clutch thrust washer may wear down the flywheel bushing prematurely, causing an excessive vibration condition.

Diagnostic Tips The bearing growl/rattle-type noise and or vibration is eliminated with the clutch fully engaged or disengaged.

Correction Replace the flywheel assembly with a Dual-Mass Flywheel, P/N 24232434. Refer to the applicable SI procedure below.

Important: The eight flywheel mounting bolts, P/N 97226124, must be replaced when service requires removal or replacement of the flywheel.

Ian

IAW a sticker on the driver's door, my truck was built in Flint, MI. I took delivery on the truck from my local GMC dealer Sept 14, 2004. The VIN# is: 1GTHK23255F825655. From your posting, it appears that my truck is effected.

Personally, I have never seen a GMC bulletin. Your posting says to discard bulletin 04-07-31-006. Is there a new bulletin number? Is there any way I can get a copy of the applicable bulletin? My local dealer does not believe there is a problem. I would like some evidence to convince him.

Dave

I just gave you the applicable bulletin! The reason that it says to discard bulletin 04-07-31-006 is because "it" (the bulletin I copied for you) is version 006a. Don't get worried about all that stuff, that's simply internal stuff for the dealer. The bulletin I quoted is the latest. Take that number in to the dealership (the one with the "a") and see if they think it applies to your situation.

Ian

Ian:

Thanks for the info. I appreciate the time you took to help me.

I would like to find a good source of TSB's for my truck. I tried alldata.com, but the TSB you referred to was not available. I used the TSB# you provided as a sample to search alldata's database.

I am willing to pay any reasonable price for the TSB's. Helm will sell them, but you need the TSB number first.

Do you know of any source besides alldata.com that has a complete selection of TSB's for my truck, or at least a database of TSB numbers & descriptions?

Dave

Well, yes....I have access to GM's online Service Information...but it's not available to the public. Are you not able to simply print out the newsgroup message that I sent with the TSB in the body? That's what I was attempting to do, give you the full copy of the TSB in the newsgroup message, all you have to do is make a copy of it.

Unfortunately, I can't sell you the TSB's, but I can and will copy them for you in a newsgroup message. If you want to simply browse through all the bulletins that pertain to your truck, I can't help you there. For the most part, that would end up being interesting, but a big waste of your time. You would see issues that will probably not appear on your truck, but will end up worrying you to no end. Or, you might end up being the kind of person that we see occasionally in the dealership...always in there with handfuls of bulletins demanding this/that/and the other be fixed. Bulletins are designed to apply to a problem that your vehicle "might" have. Even I (some techs might) don't bother trying to read "all" the bulletins...it's too tedious. If it's a slow day, I might browse the "new" bulletins to see what's coming down the line, and every now and then I catch an interesting bulletin that I'll be able to use, but for the most part, I don't bother with looking up bulletins until I'm faced with a particular problem.

Ian

Ian:

To date, I have visited the dealer 3 times. The check engine light came on (required a software update), routine maintenance, and this noise problem. I will return to the dealer with the TSB you sent. I was able to copy it easily from the newsgroup. Thanks for the help!

The reason for asking for a source of TSB's is merely personal curiosity. I've always serviced my own vehicles in the past. But, with the increasing complexity of modern cars & trucks, this is getting much more difficult.

I've read summaries of TSB's in alldata.com & mycarstats.com. All I have seen are vague summaries. I've also found these sources rather incomplete. After browsing these summaries, it became rather obvious that browsing TSB's is a waste of time unless you have a specific issue to solve.

Would you object to sending me an email address? The email address for me ( snipped-for-privacy@nordquist.us) is valid.

Dave