To bleed the air out of an engine hoist, you need to first locate the bleed valve or fitting. Charge the hydraulic circuit at low pressure and begin at the fitting farthest from the power supply. Loosen the fitting to allow a steady flow of oil until it runs clear, indicating the air has been expelled. If the hoist has features that limit or divide the flow, repeat the process at each point, working back towards the power supply. After the oil runs clear at all points, tighten the fittings.