porshuh

I'm sorry if this has already been discussed, but I couldn't find it by searching the forums. Has anyone received this letter and taken it to the dealer to see about getting their radiator swapped out to the newer one? I'm curious how much of a headache / how much griping I'm going to get from the dealer...

I was well aware that there were several lawsuits about the overheating condition, but never knew it actually got to GM sending out letters about free replacement!

EVRGRN

Check out the c7 z06 Discussion section for related threads.

For affected owners new to this subject:
Bear in mind that you'll need to provide evidence of an actual overheating event. This letter does not mean that the indicated vehicles get a no-questions-asked, free radiator swap.

porshuh

Cool. That’s part of the reason I came here to ask - what kind of evidence do I need? The dealership I just went to said if I bring the car to their dealership the next day or two after it goes into limp mode - the car *should* retain some sort of code they can pull to validate it did in fact go into limp mode.

Does anyone have any confirmation of this?

I’m assuming a GoPro video inside the car showing it would not suffice...

SladeX

Go pro video is iffy; if you have a code set (ie dash indicated reduced power mode), you will be fine for proof. Even better if you have a PDR recording of it if your car was equipped.

Unless your supercharger intercooler was not filled correctly; ie air bubbles trapped in cooling bricks; excessive air in reservoir. It is near impossible to hit this condition with street driving short of driving in the middle of a massivle 110F heatwave stuck in traffic and revving the **** of the car AND having the bad intercooler setup.

porshuh

I did have a dash indicated reduced power mode at Dominion Speedway in VA last September 3rd - but the service person said that was a YEAR AGO (their math is interesting) and way too many cycles of the car have occurred for them to be able to tell. They *say* that if I get the car into limp mode ("dash indicated reduced power mode") and bring it to them THE NEXT DAY (their emphasis, not mine), they would...probably...be able to get the evidence they needed to warrant the replacement.

I'm just trying to get confirmation that this is true before I attempt to get my car into limp mode again.

And does anyone know that PDR will show that the car goes into reduced power mode? I have PDR, but did not remember to bring an SD card with me to record the day it went into limp mode...

(mods - are you able to move this to the C7 Z06 subforum? I meant to post there in the first place)

Bill Dearborn

Do you have an M7 or an A8? What were your coolant and oil temps. Reduced power can be triggered by high coolant temp (262 deg) or high oil temp (320 deg). When you saw the reduced power indication on the IP what happened to the car and what was your response.

The PDR not only captures video it also captures a lot of the car's vehicle health and performance information.
For example, you can process the raw video with Cosworth Tool Box (free download from Cosworth) and get a screen that looks like this:


Once you have that screen do a screen capture to get a .jpg picture file and you have your data ready to print or email to the dealer.

Along with that, I would include the video and the following performance info:


There was a GMPP Secondary Radiator kit that became available starting in late December 2015/early 2016 that cost ~$950. The kit was advertised to drop oil and coolant temps an average of 14 degrees and was for the Z06 and Z51 cars. I installed that kit in my 2015 Z06 M7 in early 2016 before I ever took it to the track and have never come close to overheating the car. The data in the two pictures are from VIR.

GM made the Secondary Radiator standard in M7 Z06/GS cars starting in 2017. I don't know for sure whether or not it was also made standard in Z51s at the same time.

If you have an M7 you will get the Secondary Radiator and the proper plastic ducts/hoses to configure the car like a 2017+ M7. If you have an A8 you will have the 2019 A8 radiator installed (which is thicker than the previous model year A8 radiators) along with a change in transmission programming.

If you aren't driving on a track it will be almost impossible to get the car into limp home mode. You can't just block the radiator and let the car idle until it overheats since that doesn't meet the qualifying conditions stated in the letter: "when driven on a
track at sustained high speeds in high ambient temperatures". I suspect a high ambient temp would be anything over 86 deg F since Tadge stated they used that number when developing the car.

Bill

porshuh

I have a 2016 M7. The car went into limp mode on track due to high coolant temp (though I don't remember what the number was). There was a persistent car "alert" ding (much like other dummy alerts like trunk is open or hood is open or whatever)...the car drove and engine felt/sounded fine - just noticeably much less power.

I immediately did the rest of the session as my mother would drive the car to give it a thorough cool down. It cooled down immediately, but I made that my last track session in that weather (~95*F ambient temps in the mid afternoon. I'm sure track surface temps were through the roof).

That data log method using cosworth looks awesome. I'm just trying to get an answer from the dealer as to exactly what they will take as "proof" to get approval to do the replacement. I'm not sure that it would ever be an issue again, but would really like to get the updated secondary radiator that all the 17+ Z06es had.

Bill Dearborn

Ordering General Motors Performance Parts (GMPP) Part Number 84309470 will get you pretty much the same thing although you will need to cut the lower radiator duct to install the secondary radiator. The coverage in the letter removes the old radiator duct and installs a newer version that is preshaped to fit the secondary radiator. When I installed this radiator in my Z06 back in Feb of 2016 I checked the various online providers (Cultrag, GMPartsDirect, Trunk Monkey, etc) to get a price with shipping and then went to my local dealer parts department and negotiated a price equal to what it would have cost to have the part shipped to me. The local dealer came in with a price that was $20 higher and they would be able to get the part within two days so I went with them.

I never had a reduced power episode in ~5000 track miles and I since I did the conversion before I ever took the car to the track I never had a code or video showing the car overheating so I know I will never qualify for the coverage.

Bill