AZDoug

Noticed a couple times. I pull out garage, make hard right turn, straighten out, stop, go forward, and like someone flipped switch, i get a growling, even at a couple MPH. Comes and goes, mostly gone after 1/4 mile.

Once I get on the street, it is hard to tell over tire noise if it is there, but doesn't do it once car is fully warmed, stopped and started again.

Doesn't sound like typical R&P gear whine that I remember from years ago..

Thoughts?

Could it be brake pad dragging/shudder? (non-Z07)

Thanks,
Doug

dcher

I have the same noise you describe. Car seems to be OK otherwise. I now have 8600 miles since March of 2015. Do you have an A8?

AZDoug

Yes on the A8.

Doug

xp800

Could be the ediff purge pump. I notice mine more when it's cold out. Seems to have more to do with distance than how long the car has been running. And it does seem to be done with its business before I've left my neighborhood. It been the same with both my Z51 and the ediff is common hardware with the Z06.

AZDoug

That seems plausible as the noise is constant, it doesn't seem to vary with speed, and is does sound like some sort of pump, now that i think back to it.

What does this purge pump do? it is the pump that sends the diff fluid through the cooler?

Thanks,
Doug

xp800

The ediff (eLSD) hydraulics are an entirely separate system with its own fluid than the differential. It provides external "electronic" controlled hydraulics for the clutches in the diff. The differential system has a cooler, as well as the transmission for a Z51/Z06. I don't believe the ediff module has a cooler.

In trying to recall the discussions of this a while back, I believe the purge pump primes the line pressures and purges any air for proper ediff function.

The link below identifies the system with a bit of insight based on the service procedure:

https://www.corvetteforum.com/forums...ice-specs.html