This bulletin applies to 2006-2012 Chevy Corvette Z06, 2009-2012 ZR1 and 2010-2012 Grand Sport, equipped with a 6.0L or 7.0L LS9, LS3 or LS7 engine equipped with a dry sump oiling system.
Some customers may complain about a rattle or tapping noise that is heard under the hood at just above idle, usually 1,200 to 2,200 rpm. In some cases, this noise may also be heard on the inside of the vehicle, more pronounced on the passenger side.
The noise may be caused by the internal transfer tube in the engine oil tank hitting the inside of the tank cover. The O-ring seal that secures the tube may split or slide down the tube, allowing the tube to be loose.
Diagnose the noise by raising the vehicle on a hoist and holding the throttle at about 1,500 rpm to duplicate the condition. Use a stethoscope or chassis ears and place them on the side of the engine oil tank. If the noise is detected, perform the following procedure.
1. Remove the engine oil tank.
2. Remove the eight bolts that secure the tank top.
3. Separate the tank. Inspect the O-ring seal for damage and position. If needed, replace the seal with P/N 24576940.
4. Reinstall the tank top and secure with the eight bolts.
5. Install the tank.