Grease Gun Problem

[expat]

I have an Alemite A500 Grease gun, http://www.amazon.com/Alemite-500-Develops-Delivery-Cartridge/dp/B009K52WNY
I use 24oz cartridges, it has worked well the last 25 years
until today!

To change a cartridge I will pull the piston down from the bottom the gun body. Lock it down.
unscrew the pump. remove the old cartridge. put in a new cartridge. open it with the Ring Pull.
screw the pump back on.
Then release the piston rod, and push it back into the gun body.

Today, no matter how I tried, the piston won't go back in.

That is, until I thoughtlessly unscrewed the pump, then it shot out a whole tube of grease on the garage floor

 

[Eddie]

I've had that happen when the back of the cartridge was dented.

 

[Merkava_4]

Originally Posted By: Eddie
I've had that happen when the back of the cartridge was dented.


Interesting!! I would have never thought of that.

 

[expat]

After dumping the contents of a new cartridge, I inserted another.
Same thing, the piston rod won't go in.

It's hanging in the workshop now. All but about 2" of the length of the piston rod is sticking out the body.

 

[pcoxe]

On some guns the rod is keyed to the piston so that when rotated one way it stays connected to the piston so you can judge the amount of grease by the extended length of the piston, or force the grease if it won't move by the spring only. If you can line up the keyway, the rod will collapse through the piston so that the gun isn't so long. Since your gun threw out the grease when you unscrewed the pump, I'd say this is the problem.

 

[expat]

Originally Posted By: pcoxe
On some guns the rod is keyed to the piston so that when rotated one way it stays connected to the piston so you can judge the amount of grease by the extended length of the piston, or force the grease if it won't move by the spring only. If you can line up the keyway, the rod will collapse through the piston so that the gun isn't so long. Since your gun threw out the grease when you unscrewed the pump, I'd say this is the problem.


Bingo!

The T handle had become partially unscrewed on the piston rod, so turning the handle was having no effect, until it had rotated twice to tighten on the rod.

All is well now, many thanks!