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I accumulated 20 hours of HPDE track time on my C6Z so I started to change the transmission, differential, and power steering fluids.
While removing the differential lower tube to drain the oil I could hear air rushing into the differential. I had the car on the track two days before the oil change.
I am curious if the differential is vented and why was the differential at a lower pressure than ambient. If there is a vent can you get at it to clean it?
Mainly I do not want the differential at a higher pressure than atm. Currently all the axle seals are dry, no signs of oil seepage anywhere.
I can't say for sure about the Z cars, since they are cooled, but the base cars definitely do. Here's a pic of mine out of my car. You can see the vent on the top above the driver side axle.
I've been searching for information on how the differential vent works and have not found much info.
From what I did find is what I think is a pressure relief valve consisting of a spring and a rubber gasket.
When the differential gets hot the internal pressure increases. If the pressure exceeds the relief valve setpoint the valve opens. Now the internal diff pressure is the same as atmospheric.
When the differential cools down the internal pressure is always lower than atm. Which is why I heard air rushing into the diff case. So mine is functioning normally.
Normally the differential is always at or below the atmospheric pressure. This helps with any oil seepage since the diff is never above atmospheric pressure.
I am still under the car and will check for access.
I am replacing the left CV Axle because I noticed the inner rubber boot started slinging grease.
I have the axle and shock removed. The control arms are separated at the upper ball joint. You can see the valve but there is not enough clearance to access the valve from the wheel well. The left exhaust pipe, as well as the transmission and differential cooling lines are in the way.
If you remove the left exhaust pipe & muffler it looks like there would be ample room to access the valve from the rear.
Is The Differential Vented?
