How To Properly Load A Grease Gun (And Why You Need To Prime It Before Use)

A grease gun is not the first item on the list when it comes to your garage toolbox. Yet, they are essential tools that add a certain feng shui to your DIY projects. In fact, grease guns are one of the best tools to complete your home tool kit. Let's say you're in the garage with a grease gun in hand. You're probably wondering if it's a giant syringe for tractor joints or just a fancy weapon against squeaks. The truth is, it is both. These guns act like syringes that push lubricant into the nooks and crannies of your machine. It is a great way to oil those bearings, U‑joints, and other tight spots that need heavy-duty lubrication.

Grease guns can be manual lever, pneumatic pistol, or battery‑powered. Whichever kind you have, including one of Harbor Freight's grease guns, its goal is to deliver grease into friction-ridden areas. Yes, even a Milwaukee battery-powered grease gun is not left out. However, loading it properly matters. If not done properly, you could face a plethora of problems. For instance, it could trap air, which in turn leads to sputters, blank pumps, or no grease at all. That's why you need to not only load it properly, but also prime it. With that said, here's how to properly load a grease gun and why you need to prime it before use.

Loading a grease gun usually involves a cartridge. However, you can also bulk-load from a bin of grease by dipping the barrel and pulling back the rod until it fills. Both methods rely on eliminating air while ensuring contact between grease and the pumping mechanism.

To break it down, start by holding the gun and twisting the barrel off from the gun head. Set the head aside to avoid contamination. Next, extend the plunger rod fully and latch it into position. This creates space for the grease cartridge or bulk load. Proceed to remove the cap from a new cartridge and slide it into the barrel, open-end first. Be sure to press it firmly so it sets properly. Then, peel off or puncture the seal so grease can flow forward. If you're bulk loading, dip the barrel into a tub of grease and slowly pull back the plunger until grease fills the tube.

Once loaded, screw the barrel back to the head, but don't tighten it. Leave about one or two turns free to allow trapped air to escape during priming. Once you do that, unlock or release the rod handle so it pushes the grease forward under light pressure. Pump the trigger and keep pumping until grease flows steadily from the nozzle. Once grease emerges consistently, fully tighten the barrel head and the gun is primed and ready to use. You'll be glad to have such a tool when the time comes to use it.