2005 Corvette: GM TechLink: Axle Vent Noise
It's common for a drive axle to be vented to atmosphere to account for internal pressure changes as the axle heats up and cools down. The vent on the 2005 Corvette is unique.
A check valve relieves pressure as heat builds up. It's set to open at 0.7 psi (4.8 kPa).
However, this vent doesn't allow air back in during cooldown, to prevent water intrusion. As the air cools down, it can pull a vacuum of between 3 and 5 psi (20-34 kPa).
Consequently, is possible to hear a hissing sound when removing the oil plug. This is normal, and results from air entering the axle.
TIP: The sound may be mistaken for pressurized air escaping.
- Thanks to Dave Howe, GM TechLink, February 2005
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