Why and What to Do When Your Grease Gun Stuck on Fitting?

A common request for advice when operating grease guns for the lubrification of equipment is what to do when a grease gun is stuck on a fitting or a pin. Grease pins and grease fittings are basically the same things. These fittings or pins will be on every piece of equipment that requires lubrication within a joint that is sealed.

Both pins and fittings permit you to attach a grease gun so you can inject a lubricant into the joint. These fittings need to be clean of debris particles, dirt, and grease that has hardened always. A zerk fitting or grease pin will maintain its efficacy for greasing purposes when it is clean.

First off let’s consider why your grease gun nozzle that was relatively easy to put onto the fitting, all of a sudden won’t come off. Generally speaking, grease guns remain stuck on fittings because the zerk fitting is clogged.

The obstruction of the fitting will not permit grease to pass through it. With no passage, pressure will build up and this blocks the release. Several procedures can help you to resolve this situation.

How to Release Built up Pressure?

The quickest thing to try is to unscrew the flexible hose or rigid extension from the grease gun. This simple act should release a sufficient amount of pressure to permit the release of the grease gun hose that is still attached.

With the pop-on fitting, you can try bending the hose gently to one side while turning it anticlockwise and this may be enough for it to pop off.

Or you may be more comfortable using pliers. Clamp the pliers onto the coupler at the top of the hose and not onto the hose itself. Twist a half-turn anticlockwise and the grease hose should pull right out.

Preventing Grease Gun Sticking:

To avoid your gun sticking on a fitting in the future, the zerk fitting will need to be completely clear. Solvents can be used for this and tools similar to grease guns are available for the insertion of a high-pressure solvent to break up a clog.

Another quick solution that does not require solvents or special tools is to heat up a blocked fitting using a heat gun. If you do not own a heat gun or have access to one, a basic hairdryer will do the trick.

Set your heat gun or hairdryer on the low heat setting and point it in the direction of the zerk fitting.

After heating, reattach the grease gun immediately and pump. If the old grease in the fitting is sufficiently soft, the pressure from the new grease should be able to move the older grease and unclog your fitting.

Should either of these solutions prove to be ineffective, you may need to remove clogged grease fittings with a wrench or pair of pliers and then proceeding to clean them. Follow these simple steps.

Step 1: Unscrew any and all grease pins or fittings that appear to be clogged using the correct size wrench or pliers.

Step 2: Spray them with a basic lubricant. Allow the lubricant to sit for a few seconds to loosen dirt, debris, or hardened grease that is stuck to the fitting.

Step 3: Wipe the fitting thoroughly with a clean rag.

Step 4: Replace your fittings onto your equipment and you are ready to grease.

What Size Drill and Tap for Grease Fittings?

To be able to use a grease gun on a piece of machinery, you need to drill a hole in the machine first. Then, you can tap the hole to create a thread for the grease fittings. There are so many sizes of grease fittings and the required drill and tap drill to use depend on the size of the fittings.

In the table below, you’ll find the thread size of the grease fittings, the appropriate tap drill for each fitting size, and the drill selection for spin drive fittings. Kindly note that there are many more sizes of grease fittings, but the ones in the table below are the commonest ones.

Fitting Thread Size Tap Drill Selection for Standard Thread Fittings Drill Size Selection for Spin Drive Fittings
1/4″-28 #3 (for soft metal, use #5) “A” – .234″ Diameter
5/16″-32 9/32″ (for soft metal, use “J”)  
1/8″ Pipe 11/32″ (for soft metal, use “R”) 3/8 – .375″ Diameter
1/4″ Pipe 7/16″  


Zerk Fitting Damage – If you try to remove a stuck grease gun from the zerk fitting, it may suffer damage depending on what tool you use.

In this case. remove your zerk fitting and replace it.

Over Greasing – The owner’s manual of the piece of equipment you are greasing will indicate the amount of grease to use. Follow the manufacturer’s recommendations to avoid under or over greasing.

Zerk Fitting Maintenance – It is important that your zerk fitting is clean to avoid debris or dirt contaminating and entering the joints of your equipment during greasing.

Coupler Tips – The coupler or part that will snap onto a zerk fitting may be adjustable so that it can fit various sizes of zerks. If the sizing adjustment mechanism is too tight you probably can still insert it onto the fitting but not remove it.

You can attempt to turn the tip’s casing while holding steady the hose connection to enable release. When tightening an adjustable coupler, remember to tighten enough so that grease will not leak and no more.

Grease Gun Stuck on Fitting


With a bit of patience and one of these methods, you will be able to remove a stuck grease gun from a zerk fitting, however, the best solution will be to prevent sticking through maintenance.

Regular cleaning of your zerk fittings to remove dirt, debris, and old grease residue that has hardened will go a long way in preventing your grease gun from sticking.