How to Bleed a Grease Gun

Regardless of the type of grease gun you own or use, whether it be a manual lever, pistol grip, pneumatic air-powered, cordless electric, or mini grease gun, one of the most common problems you will run across are air pockets trapped in the gun.

An air pocket can impede and interrupt the continuous flow of lubricant while you are greasing your equipment or machinery. It will literally block the air pressure that you are trying to pump with. Continuing to pump your gun to try and force the grease out risks doing damage to your grease gun.

For this reason, many grease gun designs include an air bleeder valve to assist you in resolving this problem quickly and easily. Often, when you reload your grease gun, either with a new cartridge or even manually, air can become trapped in the grease load even without you realizing it.

This is especially common when spooning grease into a gun and packing it down manually, however, it can happen with any grease gun loading regardless of which method you use for refills.

It can also happen when your gun barrel or cartridge is almost empty or if you have purchased a new grease gun and are loading grease for the first time.

How to Bleed a Grease Gun

Preparing to Bleed a Grease Gun

You need to load your gun with grease using one of these four common methods:

  • Insertion of a grease cartridge
  • Loading through suction without a cartridge
  • Loading with a Bulk Fill Pump
  • Loading manually by spooning grease into your gun and packing it down

Priming to Expel Air

When loading or reloading a grease gun, you also need to prime your grease gun especially when it is new. With a new grease gun, both the hose and the gun will be filled with air as there is no grease yet. For this reason, you prime your gun to help expel all that unwanted air. Unfortunately, because there is no grease you end up pumping more air. So, the goal is to get the grease moving upward and out of the cartridge or barrel into the gun head.

A Constantly Primed Gun

For those that are reloading grease guns, you can keep your gun a bit primed always by simply avoiding allowing your gun to empty completely. If you pump a gun that is finishing that last bit of grease, as it empties and you are still pumping, air can enter into the grease hose.

Always finish pumping and reload while a small amount of grease is still left in the gun head and in the hose. If you need to check how much grease is still in the gun, pull the follower rod downward because it will stop as soon as it touches the follower plate that is positioned at the bottom of the grease load. That will tell you how much grease is still inside the gun.

Bleeding a Grease Gun

When you hear or read “Bleeding” in reference to a grease gun it means bleeding the air out of your gun. Some grease guns will have an air bleed valve that screws into the gun generally at the top of the gun.

As it is normal for some air to get trapped inside during a reload or cartridge substitution, bleeding your gun becomes necessary for the correct functioning of the gun.

Step 1: Open the grease gun barrel and prepare the gun

Remove the empty grease cartridge if you are reloading. If the gun is new remove the gun tube so it is open.

Step 2:Position the rod handle.

Pull out the rod handle completely and lock it into place.

Step 3: Prepare the grease cartridge and insert or refill the barrel tube with grease.

When using a cartridge, remove the plastic cap from the bottom of the new replacement cartridge and place it into the gun tube. Remove the metal tab from the top of the new grease cartridge and you will notice an air space at the top of the cartridge. This means that when you return the gun head to the grease barrel, the new grease will not immediately enter the gun head because of this air pocket. Even if your gun does not use a  cartridge, this is true.

Tip: Even if the pumping mechanism has a spring, it will not be sufficiently strong enough to push the entire supply of grease upward if there is an air pocket or space.

Step 4: Position the Grease Barrel

Take the newly filled barrel and screw it completely into the gun head. Now unscrew it once or twice so that it remains a bit loose. This will free the air at the top.

Step 5: Bleed the gun

Push the rod handle all the way into the barrel. Begin to pump or turn on the grease gun if battery operated. When a small bit of grease emerges, hold the handle pressed down and close and retighten the grease barrel.

Tip: If your grease gun has an air bleeder valve, you will not need to unscrew the gun barrel. Unscrew the air bleeder valve at the top of the gun three or four turns. A popping sound should be audible as the follower plate moves upward. A small amount of grease may emerge from the air bleeder valve. At this point close the air bleeder valve and wipe off any grease.

Step 6: Ready to Grease!

The gun is primed and ready to lubricate.