Chevrolet Equinox Service Manual: Valve Lifter Priming Caution

Caution:Ensure each valve lifter is filled with clean engine oil andthe valve lifter does not tip over (plunger down) before theinstallation of the valve lifters. The loss of oil in the valvelifter lower pressure chamber or the dry stroking/cycling of thevalve lifter plunger will allow air to travel into the highpressure chamber of the valve lifter. Air in the high pressurechamber of the valve lifter may not be purged causing extensiveengine component damage.