Grease guns - what am I doing wrong?

I don't use grease guns often, but when I do it always seems like a major pain in the butt and always turns what should be a simple job into a major mess. I currently have two guns, both are the small tube size, one from harbor freight and the other from Walmart. Yes they were cheap but in theory they should do the job...

My problem is on both of them, after loading a tube, I might get a few pumps of grease out of them into whatever I'm working on and then they just cease to pump anymore. I have broken them down to analyze why this is happening and it appears the plunger and its seal are getting stuck at the of the cartridge. The problem is that the plunger is mounted on the rod in such a way that it just floats on it. It's only backed up by spring force so you can't manually force the plunger into the cartridge via the rod. So what end up happening is the plunger gets stuck and then the plunger rod just ends up slowly pushing it's way into cartridge. At that point grease ends up flowing out behind the plunger and disassembling it ends up being a giant mess.

What's frustrating is that this harbor freight gun used to work for at least one tube. Perhaps the plunger seal swelled up? Or do the cardboard tubes have a different ID then the plastic tube cartridges causing the plunger to to not work right? What am I doing wrong?

Grease tubes invariably have some air in them.  There should be a bleeder screw on the top of the gun to let the air out of the piston.  Also, you should be able to pull the loading rod out, rotate it and lock it into the piston so you can push on the piston to force the air out.

If you can't do those things, find a grease gun that has those features.

Yup, airlock.

Happens with pretty much every fresh tube.

Have to bleed it or make the apprentice do it.

Here is my procedure, based on thousands of grease tubes replaced:

-Spit out the old one

-Pull the plunger and lock into place

-Install the new tube

-thread the head back on BUT only a few threads. Just enough to keep it on

-release the plunger which compresses the grease and expels a lot of the air through the loose threads.

-Start pumping

-If it is still cranky, good grease guns have a setting where you can pull the plunger back again and lock it behind the piston. Then you can put the plunger against your chest and exert pressure while pumping the handle and that will sort it out.

I think cheaper grease guns have poorer tolerances and when you pump, some of them draw air in instead of creating vacuum so they are troublesome. My last employer bought some cheap ones and I went and pulled them out of three excavators and tossed them and asked him to not be so cheap. It's no fun greasing a large machine by hand in the rain at 6 AM and fighting a cheap grease gun is not the way to start the day. 

-Edited to say warm grease pumps easier so try warming up the loaded grease gun before you start. On a truck or machine we drop them into the exhaust pipe. 

I'm pretty sure it's not an air lock issue since I can't even get the piston to enter the cartridge with the head of the grease gun entirely off. All it does is just push the piston all the way back to end of the housing.

Unfortunately, neither of my guns have any provision for locking the piston to the shaft so maybe I just need to upgrade beyond a $20 gun. Sucks because I only need to use this thing a couple times a year.

Sounds like an air bubble to me, but I've got very limited experience with grease guns.  I like my lock n lube gun, it came with very explicit directions on how to load a tube of grease and expel any air

Cheap Grease guns can be evil beasts.  Spend a little extra and get a decent one.  I always store extra grease tubes standing on the end that the grease comes out of.  I  may have tricked myself into believing it, but they seem to not have as much problem pumping out that way. 

Well after playing around with one of them for a bit I was actually able to get one of them to work. But I had to use a utility knife to cut a lead in chamfer on the tube so the piston could actually get started in the tube. After that it actually functioned normally. A pain in the butt though. Someday I'll just have to buy a decent one.

Usually you can flip the piston over, one end is fatter than the other so they can be used for bulk grease or tubes.

Did you maybe put the piston on the wrong way around?

ShawnG said:

Usually you can flip the piston over, one end is fatter than the other so they can be used for bulk grease or tubes.

Did you maybe put the piston on the wrong way around?

It's a cheap gun. There's nothing that can be disassembled on it beyond taking the head off to load a new tube. It's all stamped shut together.

I've had the same issues. I'm going to try and find a video on this cuz I only half understood any of the fixes described above. :(

Yes this is messy but I've not had ANY tube issues.......go buy the canister of lube of choice not the refill tubes.....pull the empty tube outta the gun .....proceed to "spoon" new grease in the old tube using ,my fave a plastic knife....not all the way full but with practice you'll get the hang.....start the tube down into the gun....grab the trigger cap hose assembly and push the two together while turning to close the connection .......yes there maybe some outside goo but put that back in the cannister.....it's just grease for cryin' out loud .......go seek ZERKS.......I will admit after a few YEARS the line from the trigger to zerk connection finally gave out...no biggee getya new one grease ON!!!

Best thing I ever got was a power grease gun.  Thought it was a bit of a "what do I need that for" but yeah its that nice if you have to do a lot of greasing.

Other one I like is one that I got from the assembly floor at a major US motorcycle manufacturer.  It is a high end unit and never a trouble to get going.  It also has a clear tube and aluminum pump head.

https://www.tooldiscounter.com/product/lincoln-industrial-hd-grease-pistol-w-clear-tube-lin1134clr

Like that but with a flex hose.  Worth it...