When a grease fitting won’t take grease, the usual causes are a clogged zerk, hardened grease in the passage, or a blocked relief path.
A stuck zerk slows a job and can wreck a bearing. The fix starts with a clean gun, the right coupler bite, and a fast check of the fitting and relief path. This guide gives a simple flow that works in the shop, on farm gear, and on compact equipment. You’ll see quick tests, safe fixes, and when to swap parts.
Grease Fitting Won’t Take Grease: Quick Diagnosis
Start with the easy stuff. Wipe the nipple. Snap the coupler on square. Pump once. Watch the joint and the gun hose. No flow and a hard handle points to back pressure. Grease escaping at the coupler points to a loose jaw or a worn head. A free handle with no movement points to an empty cartridge or air in the gun.
Fast Checks And Likely Causes
| Symptom | What It Usually Means | Next Step |
|---|---|---|
| Gun handle goes rock hard | Blocked path or hardened plug | Try bleed, then deplug steps |
| Grease oozes around coupler | Coupler not seated or worn | Tighten jaws or swap coupler |
| No pressure builds | Air pocket or empty tube | Bleed gun, replace cartridge |
| Fitting wobbles or spins | Stripped threads | Replace fitting, inspect port |
| Grease exits a relief hole | Cavity already full | Purge at relief, then resume |
| One shot then stops | Check ball stuck shut | Tap lightly, then test again |
If the quick checks point to a blockage, do not force the gun. Manual guns can hit huge pressure and can blow seals. Back up and clear the path first. The steps below take only a few minutes and save parts.
Step-By-Step: Clear The Obvious Blockers
- Bleed And Prime The Gun. Crack the bleeder or loosen the head one turn. Pump until a firm stream forms. Tighten the head. A soft handle with no feed often means trapped air.
- Seat The Coupler. Adjust the jaw tension. Snap on straight. If grease leaks at the head, the jaws may be loose or the fitting is undersize. A locking coupler can help on awkward angles.
- Free A Stuck Check Ball. Use a small punch or a needle adapter. Press the ball to break varnish. Wipe away any grit. Then try one slow pump.
- Swap The Fitting. Thread in a known good zerk of the same size. If flow returns, the old one was bad. Keep a small kit with common SAE and metric sizes.
- Purge The Relief Path. Open the drain or relief. Some housings have tiny ports that clog with soap thickener. Crack the plug, pump a few strokes, then close.
Still jammed? Then the obstruction sits past the fitting. That means caked grease in a passage, a pin bore packed with dirt, or a collapsed seal that can’t pass new grease. At this point move to light deplugging. Go slow and stay gentle.
Deplug Without Damage
- Warm The Joint. A heat gun softens old soap. Keep the nozzle moving. You’re warming, not baking paint or seals.
- Use A Needle Adapter. A fine needle can push a slim path around the ball. A few tiny shots can break a plug without stress.
- Try A Low-Volume Injector Tool. These tools send a sharp pulse to crack waxed grease. Use short bursts. Stop if the seal weeps.
- Pull The Pin Or Link. On link pivots and loader pins, removal lets you clean the cross holes. A bench wipe and a pipe cleaner work wonders.
- Last Resort: Solvent Touch. A drop of light oil at the nipple can free varnish on the ball. Avoid flushing the cavity. You want grease, not solvent, inside.
Do not apply a torch. Do not smash the nipple. Heat and impact risk seals and temper. The goal is a clear path and a live bearing, not a short win that costs a teardown later.
Safety And Prep That Prevents Stuck Zerks
Lock out motion and stored energy before you grease near belts, shafts, or springs. A calm setup beats a rush near moving parts. Wipe the fitting each time and cap it on dirty jobs. Keep cartridges sealed. Dirt rides in on threads and couplers, then hardens inside the passage.
For shop policies and minimum steps on disabling equipment, see the OSHA rule on hazardous energy. Link opens in a new tab.
When The Passage, Seal, Or Cavity Is The Culprit
Some housings need a clear exit to purge. If the drain is painted shut or packed with dirt, new grease has nowhere to go. Open the relief and try again. If a lip seal lifts, stop at once and relieve pressure. Overfill can pop shields or push grease where you don’t want it.
If the joint sat through a season, grease may have dried into a waxy plug. Gentle heat and short pulses can free it, but plan a deeper clean. On pins with cross holes, pull the pin. Scrub the bore. Align the holes on install so grease reaches the loaded face.
Grease Choice Matters For Flow
Grease that matches speed, load, and temperature flows and feeds better. Base oil viscosity and thickener type set that behavior. A high NLGI grade resists shear but can move slow at low temps. A light grade moves fast but can thin under heat. Match the grade to the job and season.
For bearing relube timing and viscosity guidance, SKF hosts clear notes and charts in its grease life and relubrication section.
Grease And Hardware: Small Choices That Help
| Item | Why It Helps | Tip |
|---|---|---|
| Locking coupler | Holds square on worn nipples | Back off one turn for easy release |
| Needle adapter | Reaches recessed zerks | Carry two sizes |
| Pressure relief gun | Limits burst pressure | Great for shielded bearings |
| Rubber caps | Keep dirt off the ball | Cap after each service |
| Thread repair kit | Saves a loose port | Use the right tap pitch |
| Assorted zerks | Swap bad fittings on the spot | Stock SAE and metric |
Match The Fitting: SAE And Metric
Wrong threads cause leaks and clogs. Most light equipment in North America uses 1/4-28 taper or 1/8 NPT. Plenty of compact tractors and imports use metric zerks. If a nipple feels loose or won’t seat, stop and check the spec before you force it.
Keep a small chart in the toolbox. Measure the thread, count the pitch, and test with a spare. A fresh fitting costs little and fixes many “no feed” calls.
Common Mistakes That Keep Grease Out
- Packing Dirt Into The Nipple. Wipe first. A quick rag swipe saves loads of grief.
- Forcing High Pressure Into A Blocked Joint. This blows seals. Clear the path, then feed.
- Mixing Incompatible Greases. Soap types can gel when mixed. Purge fully when you change products.
- Ignoring Relief Ports. A closed drain keeps grease out. Open, purge, close.
- Skipping Coupler Checks. Loose jaws leak. Tight jaws damage nipples. Set them just right.
Quick Field Fix: Loader Pin With A Dry Zerk
You snap the gun on a loader pivot and the handle locks up. First, crack the bleeder and prime. Next, tighten the coupler one turn and try again. Still stalled? Tap the check ball once, swap in a new 1/4-28 zerk, open the tiny purge screw on the back side, and give two slow strokes. If grease shows at the joint, close the purge and finish with a few more pumps. If not, pull the pin and clean the cross holes.
A Simple Greasing Routine That Prevents Jams
- Stage gear and parts. Gun, rags, caps, spare zerks, and adapters within reach.
- Work in a loop. Start at one corner and circle the machine so no point gets missed.
- Purge where needed. Open drains on housings that call for it. Close after a short feed.
- Record hours. Note intervals on a tag or app so joints don’t starve or overfill.
- Store clean. Cap nipples on dusty jobs. Keep guns sealed and upright.
Fast Troubleshooting Flow
Clean → Prime gun → Seat coupler → One test pump → Pressure spike? Stop → Free ball → Swap zerk → Open relief → Short pulses with heat → If still blocked, clean the passage by pin removal. Avoid air guns on stuck joints. Manual control beats brute force.
When To Stop And Inspect
If a seal bulges, stop. If the joint will not take grease after the deplug steps, stop. A dry joint can hide wear, a cracked race, or a misaligned pin. At that stage inspection beats more pressure. Parts are cheaper than downtime from a failed pivot or bearing.
Coupler Care And Gun Setup
A tired coupler wastes time and grease. Replace the jaws when they lose bite or leave marks on every nipple. Keep the head clean, and add a drop of oil to the jaw sleeve so it slides smoothly. A flex hose helps reach tight spots; a rigid tube gives better aim in the open.
Air pockets are common after a cartridge change. Stand the gun upright, crack the bleeder, and pump slow strokes until a steady ribbon forms. Tighten the bleeder. If the handle still feels spongy, repeat the bleed. Store the gun with the plunger released to protect the spring and keep oil from separating. Label each gun by grease type so products never mix.
Quick Setup Tips
- Wrap NPT threads with tape; leave the first thread bare.
- Keep dust caps on seldom-used zerks.
- Add a pressure gauge to the gun if you work on sealed bearings.