rich5962

'07 A6 Z51 Coupe 41k miles.....Normal fun driving around, occasional quick blips getting on the highway(love that part), never too hard on the car, frequently passed by seniors driving 4cylinder buggies.....

Sorry, kinda' long but more info for future reference.

This past Sunday noticed a rattling noise which I thought was in the engine area. Sounded like a noisy AC tensioner or main belt idler or tensioner. It happens only in Drive or Reverse at rest, idling, with foot brake applied or ebrake applied. Like sitting at a red light. If I shut the AC off it seemed to go away.

When I got home I opened the hood while it was making the noise, sometimes in neutral, but more noticeable with AC on. Noticed the harmonic balancer(aka crank pulley) was wobbling. Stopped the engine and saw that the rubber insulator was a bit deformed.

Brought it to my dealer for service Monday. They had the parts in stock and replaced the balancer, new bolt, 2 new belts. I read the procedure in my service manuls. Big job. Excluding belts was covered under the 5yr/100k mile powertrain warranty. They checked the AC & main tensioners and idler pulley were all ok.

Picked it up yesterday, but noticed a few minutes later driving home at a light the rattling noise was still there. Doesn't appear to happen till it's fully warmed up. Took it home and decided to pull and check the AC tensioner myself. They were right, it was ok. Reinstalled and ran the engine again. Still rattling noise.

As it turns out, the noise is really in the rear of the car. It tricked me thinking it was up front. I put the car up on a (2 post)lift with engine running in Drive with brake on and AC running. Rattling noise coming from the transaxle area. I checked exhaust/hangers, floor plates, etc and no change. Seems like it's at the torque converter area. Maybe loose bolts, bad bearings? Called the dealer. Back up there again today.

The service writer and tech heard it right away. I explained that's the sound I heard Sunday. The balancer needed to be changed anyways as it was defective, but didn't solve the original problem. The in/out mileage was only 2 miles so they didn't hear it after the balancer work. It's in the rear. The sound is like a internally broken catalytic converter, or tensioner/idler rattle if you know what I mean.

They called me late today. On a lift they verified where the noise is coming from. Tomorrow morning the transmission tech with be working on it.

Could be 2 major repairs in one week. Will update when I get the word.

Rich

Piratesoul

Any word on the problem?

I am trying to diagnose a very similar noise.

bklyn vette

I had the same problem with my 07 c6...under acceleration i heard a crazynoise that i belived was coming from the motor....when i got home i put the car on a lift and with a friends help we heard the noise from the back of the car....when i brought the car to the dealer the bolts backed out of the tourqe tube causing this crazy noise they replaced the bolts......no more noise

rich5962

My car is still at the dealer. Their tranny expert was out Thurs and Fri with an emergency. They're looking at it this morning.(service dept open today, Saturday)

When I spoke with them yesterday they suspected the bearing at the end of the torque tube. I think I'm going to take a ride up and talk to them right now after reading the reply from "bklyn vette".

bklyn vette
Exactly which bolts are you referring to? The tube to converter housing?

Thanks,
Rich

bklyn vette

internal bolts at the end of tube...not exposed holding housing.

rich5962

Update....

The service tech suspects the problem is the nut that holds the converter input shaft to the yoke. My adviser said there is a service bulletin, PID4466 which addresses this.(I may have the "PID" wrong). It replaces the nut and instructs the use of locktite when assembled. I looked online to try to find the service bulletin but I cannot. I never made it to the dealer today so I don't have a copy of it. I won't know any more until Monday.

I looked at the procedure in my service manuals to do this work. In order to get in there, the torque tube assy and transaxle must come out, along with dropping part of the rear crossmember. I'm not happy this is happening, but I am happy this is all covered in the PT warranty.

If anyone has access to the TSB's please see if you can find it. If it turns out the nut was loose, I have concerns about the splined shaft, the yoke housing, the 2 bearings, and seal.

Here they go taking my car apart again, this time the back half.

more to come.....

bklyn vette

this is what happend to me.....good luck.....let us know..sorry I dont have the tsb#

rich5962

Fixed............

After a week or so of waiting for parts the car is fixed. 2 bearings were replaced in the rear prop shaft housing. This housing connects the driveshaft(propeller shaft) to the rear housing at the yoke and spindle, which connects to the flexplate, which connects to the torque converter, etc, etc. The tech said only the forward bearing was bad but both were replaced, along with a new spindle nut(threadlocked this time). This was a big job to repair. Transmission must come out to get to the bearings. Flat rate is 7+ hrs labor.

Part #'s
1- 89059716 Nut
2- 12456221 Bearings

Below is a copy of the document I mentioned in the earlier post.
----------------

Document ID: 2184842
#PIP4466: Rattle Noise At Idle From Front Of Transmission Area - keywords bearing driveshaft prop propshaft shaft torque tube - (Sep 4, 2008)

2006-2009 Cadillac XLR 2006-2009 Chevrolet Corvette

Equipped with 6L80 (RPO - MYC) Automatic Transmission

CONDITION/CONCERN:
Some customers may comment on a rattle noise at idle with the transmission in gear. This noise may be heard from the area of the rear of the driveline

support and front of the transmission.

RECOMMENDATION/INSTRUCTIONS:
This conditions may be caused by the driveline support, rear prop shaft coupling nut (1) being loose allowing the hub (2) to move on the flexplate spindle (11) (see SI document 499587 for illustration). This nut should be torqued to 90 Nm (60 Ib ft). If the nut is found to be loose remove the nut, clean the threads and apply thread lock PIN 12345382 (Canada PIN 10953489) or equivalent to the threads of the spindle. Tighten the nut to 90 Nm (60 Ib ft). If the nut is not loose inspect the torque tube bearings prior to replacement of the torque converter or transmission oil pump.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.

GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicies, or to provide information that couid aSSist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicie will have that condition. See your GM dealer for information on whether your vehicie may benefit from the information.

-------------

RicK T

Don't recall seeing this problem before. Thanks for posting the info. Hope that's it for you.

Nd4spd2

Good info, thanks

rich5962

Just an update...... Yesterday I stopped by the dealer that did the work. I've been wondering why this bearing went bad. According to the technician that worked on it, the new bearings are a permanently lubricated "sealed" type bearing. The original bearings were not the sealed type as I was told. I have only 41k miles on the car.

The rubber cap that covers the flexplate/torque converter access hole in the rear housing was missing before they worked on it. I know as I had the car on a lift when I diagnosed the noise. The cap is about 3"x4" trapezoid shape. I don't know how long it was missing, but the failed bearing had some contamination in it, possibly caused by water getting in that area. These bearings have no access for inspection or lubrication. They replaced the cap as part of the warranty work. Either contamination or poorly designed bearing application(not sealed type) caused this. Clearly the new sealed bearings should prevent this from happening.

So.......Next time you're under you cars, make sure that the rear housing rubber access cap(auto or manual trans) has not fallen off. Also check the front rubber access cap at the flywheel/bellhousing of the engine.

Particularly '05 and '06 owners that don't have the 100k powertrain warranty or extended coverage.

Rich

sam-garcia

I'm sorry if I've already asked you or if I'm accidentally spamming the same threads but can someone listen to this noise and let me know if they've heard it before...It's driving me nuts as evidenced by all the old threads that I've been reviving lol

rich5962

I listened several times but having difficulty hearing the noise. Can you tell us the exact timestamps when it happens?

Since it's a manual I'd think it's not the rear prop shaft housing bearings like on the AT 6L80s. But could it be(rhetorically) the loose spine nut syndrome(TSB above), if the configuration is similar?

MARSC6

With car idling in neutral try to listen underneath it and determine source of noise. Reminds me of torque tube bearings but can't give answer by listening to someone else's video.

sam-garcia

Hey rich thanks for getting back to me. I've updated the YouTube link. If you click on the description I linked the timestamps where the noise is heard. It's the loudest about 0:51 to 1:01 seconds into the video.
The sound can be heard at the following time stamps:
0:04 to 0:07
0:12 to 0:14
0:18 to 0:20
0:51 to 1:01
1:05 to 1:09
1:15 to 1:17

How does the noise I'm hearing compare to the noise you had?

sam-garcia

I tried that but unfortunately the noise only seems to happen while the car is under load. That video is of my car. You can hear the noise the most distinctly at 51 seconds to 61 seconds into the video...Unless you meant just in general someone else's video

rich5962

I saw your post & video also in my Noisy Torque Tube Thread. I read through your entire explanation. Good job describing in detail.

With your timestamps, ok hear it now.Since only under load, maybe a exhaust pipe hitting somewhere. You said you got under it and heard nothing, but it was idling and not under load.

So since you can't get under the car under load, the best way would be to get it on a raised chassis dyno with someone running it through the gears under load with you and a sharp tech under it to try to locate the noise. Just wear safety glasses and lots of safety gear.

One like this. I restored a '61 a while back and ran it at my friends shop to help break in the car as it wasn't registerd so I couldn't put any miles on it.

Bypass the preptime and go to 1:40 for startup and run.

This was inside the car on the 2nd run.

sam-garcia

Thanks and nice car!!

Funny you mentioned a raised chassis dyno because I woke up wondering if such a thing existed lol. I'll start looking in my area (metro Atlanta) for a place that has one. Thanks again.