I think it goes without saying that the dyno tech is outside the room; hence the need for measuring devices in the room.

 

Well according to the owner manuel , the break in period is 1500 miles , so he didnt reach the half of it .

 

The 2024 Owner’s Manual states the same break-in procedures as 2023; but in 2024, the following is added:

“To remove the engine torque limitation after the initial 500-mile break-in period, turn the vehicle off, and open and close the driver door. Ensure all doors are closed for
15 minutes.”

Kind of weird, no?

 

Yes , sorry i didnt brief my self , i work as Team leader in chevrolet GM lebanon , i am a mechanical enginneer , a quick note , after disabling the torque limitation , they ask to maintain not an aggressive accelerations and deceleration for the total of 1500 miles ,
as per what i did know , that this vehicle was tested Dyno , of course he cant do that . untill total break in is achieved .

Cheeers

 

Of course Bowling Green still does a 20 minute dyno run on each LT6 engine including running it up to redline, and they don't wait for the full break in. Admittedly the DCT and rear gear is not attached during that dyno run.

 

Update on mine, now at 3,300 miles.
I got the Blackstone Labs report from the oil sampled one month ago at 2850 miles, right before my first oil change. The wear indicating metals: Iron, Aluminum, Copper, Tin, were all well within expected initial wear-in levels. The fuel content was negligible so gas wash is not an issue. This gives me some peace of mind to continue driving my car normally as I make decisions on the Ticking TSB repair.

I had a meeting with the Service Director at my dealer and we reviewed the TSB step-by-step. We believe the noise in mine to be on the drivers' side. He also called the regional Chevrolet Engineering rep and discussed the measurement and repair process with him. My Service Director has a good relationship with the engineering rep and has worked with him before. The rep was very familiar with the LT6 Ticking TSB process. I was not aware GM had engineering reps based locally. This made me more comfortable moving ahead with the repair knowing engineering support is close-by and can be brought in quickly when needed.

We are scheduling the PICOScope measurements on mine next week. I will report back the findings.

Charles

 

^ That sounds like a professional interaction, if only all dealers could be that way.

 

First let me say my noise got significantly quieter last week. Until then It was very loud and could be heard at idle both inside the car with the windows up and from 20-30 feet away with the coupe hatch closed and exhaust in tour mode. The only thing I did was make a full throttle run to redline in the first few gears and take a very spirited drive in track mode with hard downshifts for about 15 miles last week. After driving the car hard I noticed the tick was a lot quieter.

Since I already had the appointment for the PICOScope measurement yesterday we went ahead and did it. Without getting into too much detail, let me say my service department was great and kept me very involved in the process. It was their first time doing the TSB procedure so it took a little longer and the measurements were taken multiple times to be sure they were right. They did both the left and right banks. Now that they have experience with procedure, it would only take less than 30 minutes to set up and take readings on both banks.
I was able to view the graphs. As we expected, the left side was slightly worse than the right. Even the left was much closer to the “no-tick” example than the “with-tick” in the TSB.
My Service Director emailed the saved PICOScope files to engineering and we are waiting for their recommendation.

As of now, both the Service Director and I are leaning towards letting it be and NOT trying the repair unless it gets worse again. We will see what engineering says.

 

I’ll chime in with my experience so far with the tick. Took my Z to the local dealer about 2 weeks ago to discuss the issue. Neither the service manager or service rep I spoke with were aware of the issue. They had not seen a new Z06 before mine. I showed them the TSB and both thought, just from listening, that my tick was likely too loud so we scheduled the PICO to confirm. A few days later they confirmed via the PICO that the tick was indeed loud and eligible for the “fix”. I told them I wanted it done. They had to order the parts required and a few days later performed the procedure as outlined in the TSB.
I picked my car up yesterday and they reviewed the before and after PICOs with me. Frankly, I couldn’t see a difference and they couldn’t explain where there was a difference, but they were adamant the tick was greatly reduced. They were right. It was reduced. Still present but not as loud.
I’m trying to decide if I should attempt to get a better explanation of the PICO results to determine if the post fix PICO should look significantly different than the pre fix (mine wasn’t) and if my car needs further repairs.

 

The regional Corvette engineers are involved with this issue. Ask for one of them to explain it to you since they are very familiar with this issue/TSB.

 

Thanks. I will give it a shot.

 

Smithers, Was at Green Mountain last week. I asked them about engine and transmission failures in the C8 and the Z06. They told me they had 0.
I believe to the many that have been built that the percentage is really low with problems. It happens with all vehicles.

 

I don't believe that for a second... that's what they're told to say. If a car has an issue it's swapped out and serviced.

 

I can see why the courts place the burden of proof on the prosecution.

 

My Service Director heard back from engineering.
The regional rep agreed the picoScope measurements were at the low end of noticeable. While not giving a hard recommendation, he was leaning toward the leave it alone and wait to see it the noise gets worse again approach.

I will continue to do an oil analysis at least every 3,000 miles and monitor the noise. Otherwise I am going to drive the #@%$ out of the car and enjoy it!

Here is a screen shot of the left bank:



Charles

 

Really, that's great for you. My Brand New C8 Z06 crapped out the day I brought it home with multiple system failures and not drivable. same day I took it home it was flat bedded back to the dealer. GM and the dealer told me it could take months to get the parts to fix it.
Brand new car can't drive it for months, UNACCEPTABLE! My Lawyer is going after GM. And yes, I babied the car on the way home from the dealership never went over 3500 rpm. Go figure.

 

was your issue diagnosed as engine related? I thought it was a front lift helper bag leaking hydraulic fluid and took out a module or something?

 

Guessing trans leak onto exhaust…

 

From what I've understood from all the engineers at team corvette, they recommended NO launches and NO track use for 1500. I recall Tadge in an interview where he stated that he'd wait to even 2000 miles before getting more aggressive with the DCT. The once in a while fast acceleration won't bother it if you're rolling, but hard launches and heavy shifting prior to break in could definitely be an issue with some transmission failures. The engine break in was noted to be 500, however, more is better with this too. I really didn't get my RPMs up past 5000 until about 700+ miles.
I currently have 1582 miles on mine now and it's been great. I changed my oil at 1532 miles and it looked very clean. The filter did too. There might have been about 3 tiny shinny metal specs that I could see in the fins of the filter but that was it and it's possible it was just the fiber shimmering in the sunlight at the time. It seemed like after I changed the oil and took it for a ride that it drove even better. Maybe that's just in my head

I'm knocking on wood but perhaps I'm just lucky for now. I'll continue with my current driving methods till about 2k. Then I'll try launch control. I did some parade laps with it at Lime Rock Park( I was the only C8Z06 there) but that wasn't anything harsh. Brought it up to about 110 on the straight and being paced laps we didn't get crazy in the corners. I was able to feel the potential of the car though. I can't wait to really get this thing on the track at some point.

 

You're off-base with the recommendation/interpretations and blaming this all on "abuse". People are having leaking transmissions at PDI or after only a few hundred miles of use. There are case porosity issues (bad castings) and various gasket and seal issues. If GM wanted to break-in to be differently they would have stated as such. The engine is broken in at assembly and first run-in. The other guidelines (500 and 1,500) are for the DCT gears to develop sufficient wear-patterns for a long service-life. The first 500 miles they suggest a lower redline and torque management is active. No launches, no hard use etc. From 500-1,500 you can launch and use the car, but no trackday use i.e. extended high heat or extended loading of the car.

The main issue sets with these cars so far are:

1. Engine vale lash (the tick)
2. Trans leaks (porosity, parts defects)
3. Trans debris causing premature valve-body failure (assembly debris, poor valvebody design)

One member is on his 4th valvebody and was told they recently redesigned it.

GM is adamant that the break-in is 7,500 and if you do the trans filter early, you MUST do it again at 7,500 to have warranty. On all 3 of my Stingrays I do the first oil change and trans filter at 2,000 miles and then again within 7,500 more. This was all before GM clarified the "YOU MUST DO IT AT 7,500 NO MATTER WHAT" update.

For my Z06 I will do oil and trans filter when I get it home from the NCM (about 1,200 miles) and then again at 7,500.