How to Get Air out of a Cartridge-Type Grease Gun
Normally when replacing grease in a cartridge-type grease gun, it is not necessary to bleed the air out. However, if the grease does not flow through the nozzle evenly, the air must be bled from the grease gun. There is usually a valve on the top of the unit to get air out of a cartridge-type grease gun. This valve allows air to pass through without leaking grease. It might take several attempts to remove the majority of the air pockets within the cartridge and grease gun.