toppee

Sharne here from New Zealand.
I have a 2016 Z06 with the 8 speed auto.Only done 7400 miles. I have never tracked the car or abused the car.
Im sorry to say that ive had so much trouble with this car.
First the diff had to be replaced with a new one (started to wine) ,and the car ran great for a while, then trouble with the transmission, so they put a new trans in.

The trouble i have now is when I start to slowly accelerate a loud pump or motor noise starts at the rear left side of the car. It goes away after I reach around 35-40 mph. A service rear axle message appeared but it hasn't come back .
To me it sounds like the ELSD pump for the diff, so I disconnected the fuse #10 for the electronic rear diff module,went for a drive and I couldn't here the noise. Put the fuse back in and the noise came back. So to me its something to do with the Elsd pump.
With having the rear out twice could the pump be low on oil or maybe the module has crapped out.
Im going back to the dealer but they dont know allot about these cars here in New Zealand.
Any imfo or advice which i can go to the dealer would be much appreciated.
Thank you.

tertiumquid

The differential whine was a fairly common problem on the 2016's after 10K miles or so. I had the same problem with my 2016 and it took forever to get a replacement unit. The noise you're hearing has to be the pump unit, the cause is anybody's guess but your dealer ought to be able to contact GM in the States for some guidance.

djnice

The ELSD hydraulic system needs to be filled and bled. It is a separate fluid reservoir from the diff gears. Try this link for starters. https://www.corvetteforum.com/forums...ice-specs.html

toppee

Thank you very much for your reply guys. I have read in the manual about the bleed procedure and my gut is telling me its that. I just thought I would email on the forum in case it might have been something else.
Its a shame That I have had so much trouble with this car and Im almost ready to trade it in on a 2018 Z06 but every time I drive it I get out with a big smile on my face.
Really appreciate the help.
Sharne

azcanuk

Yikes, first I've heard of this and since I've only got about 6k on mine wondering if this is another thing that is going to crop up.. damn, those C8's might be looking a lot better than I originally thought.... So just how "common" is this issue?

tertiumquid

In fairness, it looks to me that it was probably in a portion of the model run and not necessarily as big a problem as the cracked wheels issue. Just be aware that if you start to hear a sound similar to what an old truck rear end has, whether by acceleration and deceleration but not at the exact mid point where you're not putting any torque on the differential, you've got a problem with your differential. The bad part for me and several others recently is that replacement units are scarce. My dealer got 4 units from GM; out of the first three, two had leaks from cracks in the case and the third was actually another core taken from a car with the same problem. The 4th was finally ok but the car was laid up at the dealer for 8 weeks.

toppee

When the dealer check my diff that had to be replaced it only had 2 quarts of oil. Unfortunately the car had already done 2500 miles so the diff was toast. We checked the oil in the new diff when installed. I did 3000 miles and decided to drain out old diff fluid. I was amazed how discoloured the oil was. Maybe because of the break in time?
Im thinking of doing another 3000 miles and change it again. Its not that hard to change and I think its safe insurance.
Im getting the GM diff oil on E-bay at a reasonable price.
Sounds like theirs been allot of corvettes that the diffs are low on oil.

dale fehrenbach

I have a 16 Z06 7M with 16,000 miles with zero problems. Your issues are unacceptable and I hope you get a good resolution.

azcanuk

I had the first oil change performed at 571 miles and at that time had dealer check Differential fluid level... indicated was "slightly" low, filled it up and torqued fill plug. Here is hoping I'm not subject to the noise issues due to having it checked/filled almost from day 1.

toppee

Good idea to check diff fluid. Im sure it will be fine. Im 100% certain that the low diff oil killed my diff, I know of two others that have done the same. My new diff is fine.
I dont understand how GM let this one slip on a high end sports car!
The dealer has contacted me about the pump noise and apparently it can take 3 bleed cycles to get all the air out of the ELSD diff pump and they only done it once, so theirs still air in the system and its not a big deal to fix.
So its going back to get sorted.

toppee

the dealer has bleed the ELSD pump and checked oil level and the car is running great. No more pump noise.

djnice

Thanks for following up with how the issue was resolved.