S-707DC Lever Action Grease Gun

Frequently Asked Questions: Lever Action Grease Gun

What can I use the S-707DC 6,000 PSI lever grease gun on?

The S-707DC is a 6,000 PSI general-purpose lever action grease gun for automotive, agricultural, and industrial equipment maintenance. Applications include car and light truck chassis zerks, tractor U-joints and 3-point hitch pivots, wheel bearing fittings via Bearing Buddy style caps, fleet vehicle service, forklift mast pivots, small excavator and loader pins, conveyor roller bearings, compressor bearings, and general workshop lubrication. The 14 oz. (400 g) cartridge or 500 cc (15 oz.) bulk fill capacity covers a full service shift without reloading, making this the go-to tool for workshops handling mixed automotive and agricultural work.

Is 6,000 PSI enough for a lever action grease gun?

Yes. 6,000 PSI (413 bar) suits approximately 85 percent of working grease fittings across automotive, agricultural, and light industrial service. At this pressure the S-707DC clears most chassis zerks, tractor joints, wheel bearing seals, and fleet vehicle fittings without stalling. 6,000 PSI also stays below the 7,000 PSI threshold where high-pressure injection injury risk increases sharply, making it a safer choice for mixed-experience shop staff. For badly crusted zerks on older neglected equipment, 20+ ton excavator pins, or severe industrial conditions, step up to the 12,000 PSI S-707 (steel head).

What is the output per stroke on a 6,000 PSI lever grease gun?

The S-707DC delivers 1 gram of grease per lever stroke, which equals 1 oz. per 28 strokes or a full 14 oz. / 400 g cartridge in approximately 400 strokes. This output is controlled by the 57.15 mm barrel diameter and piston stroke length. Count strokes to meter grease accurately: typical chassis zerk takes 3-5 strokes (3-5 g), U-joint 5-8 strokes, wheel bearing 10-15 strokes, heavy equipment pin 15-25 strokes. Keep a stroke-count log per service route to calibrate grease consumption per equipment type. Over-greasing damages bearing seals, so always stop at the manufacturer specified quantity rather than pumping until grease overflows.

What is a 4-way loading grease gun?

4-way loading means the S-707DC accepts four different fill methods: the standard 14 oz. / 400 g cartridge, bulk fill up to 500 cc from an open pail, suction fill through the head from an open grease container, and filler pump transfer from bulk grease drums. Most 2-way and 3-way lever guns skip one or two of these options. The 4-way flexibility lets one gun fit every workshop scenario: cartridge for clean brake and chassis work, bulk for high-volume fleet greasing, suction when cartridges are back-ordered, and filler pump for rapid reloading across a bay of guns. Switching between methods needs no tool change or head modification.

How do I load the S-707DC using suction fill?

Suction fill uses the plunger rod as a vacuum pump to draw grease directly from an open pail into the S-707DC barrel. Start by removing the coupler and extension from the head. Pull the plunger rod back 2-3 inches and lock it in the side slot. Place the open head mouth directly onto the grease surface in an open pail, then release the plunger rod from the side slot and slowly pull it through its full travel while the head stays submerged. The vacuum draws grease up through the head into the barrel. Reinstall the coupler and prime normally. Suction fill works reliably with NLGI 2 grease at room temperature. Cold stiff grease resists vacuum loading, so warm the grease to 15-20°C first or switch to bulk dip loading.

What grease gun do farmers recommend for tractor maintenance?

Yes, agricultural tractor and loader service is one of the primary applications for the S-707DC. Typical tractor greasing schedule every 50-100 operating hours: front steering kingpins (3-5 strokes), tie rod ends (3-5 strokes), drive shaft U-joints (5-8 strokes), PTO slip yokes (5-8 strokes), 3-point hitch pivots (2-4 strokes), loader arm pivots and bucket pins (5-10 strokes), front axle pivots (5-10 strokes). A typical 100 HP tractor has 15-25 grease fittings per service, well within one cartridge load. Use NLGI 2 moly EP for drive shafts and U-joints, NLGI 2 lithium for general chassis, calcium sulfonate water-resistant grease for implements that contact mud.

Can I use a lever grease gun for wheel bearings and U-joints?

Yes, the S-707DC's 6,000 PSI is ideal for wheel bearing packing via spindle fittings and U-joint greasing on drive shafts and axles. For Bearing Buddy style boat trailer and utility trailer hubs: pump one stroke at a time while watching the spring-loaded piston. Stop immediately when the piston moves forward 1-2 mm (indicates hub cavity is full). For drive shaft U-joints: pump 5-8 strokes until fresh grease appears at all 4 cross bearing caps. Never over-pump U-joint fittings. Excess pressure blows the cap seals and contaminates the bearing. Use NLGI 2 moly EP grease for U-joints to handle shock loads; NLGI 2 lithium for wheel bearings.

What is the advantage of a CNC-machined aluminium die cast head?

A CNC-machined aluminium die cast head gives precision grease-flow geometry, lightweight durability, and natural corrosion resistance while still handling sustained 6,000 PSI. The die cast process creates a dense, void-free aluminium structure, and CNC machining finishes the critical surfaces (bulk loader thread, head and barrel threading, coupler seat, bleeder port) to tight tolerances. Benefits include roughly 40 percent less weight than a steel head (reducing operator fatigue on extended service), precision-matched check valve seating for reliable priming, and corrosion resistance without plating. The trade-off is impact tolerance. Aluminium will not match forged steel if the gun is dropped repeatedly onto concrete. For drop-heavy construction and mining environments, the steel-head S-707 is the right choice.

How do I fix an air lock in the S-707DC?

Air lock on the S-707DC is cleared in seconds using the built-in bulk loader valve. Rotate the head assembly a quarter turn counter-clockwise to open the air release, pump the lever slowly for 3-5 strokes until grease flows through the loosened joint, then rotate the head back a quarter turn to close it. The gun should now pump normally, with grease flowing from the coupler within the first or second stroke. If air lock persists after that, check that the cartridge is properly seated against the head, confirm the plunger rod follower plate is still in contact with grease (not dropped below it into empty space), and inspect the plunger rod seal for wear. Air lock is the top priming failure mode on every lever gun, and the bulk loader valve resolves most cases without disassembly.

Why does the S-707DC not build pressure or prime?

A lever gun that fails to build pressure has one of four root causes: an air lock between grease and plunger (most common), a worn plunger rod seal letting pressure bypass, a one-way check valve in the head stuck from debris, or a cartridge improperly seated or empty. Troubleshoot the S-707DC in order. Start by bleeding the bulk loader valve a quarter turn and pumping until grease flows. If that fails, pull the plunger rod back to check whether grease remains in the barrel. When the gun still will not build pressure, unscrew the head and inspect the one-way check valve for grease debris, then wipe it clean with solvent. Only if the check valve is clean and the gun still fails should you suspect the plunger rod seal and replace it from the spare parts kit. Most cases resolve at the bleeder stage. Mechanical failures at the valve or seal are rare on a well-maintained gun.

Can I mix different types of grease in one grease gun?

No. Mixing incompatible grease thickeners (lithium with calcium, lithium with polyurea, calcium with aluminium complex) causes a chemical reaction that forms hard deposits, clogs check valves, and degrades lubrication performance. Symptoms include lumpy grease, erratic pumping, rapid prime loss, and loss of water resistance. Mixing across NLGI grades within the same thickener family (NLGI 1 and NLGI 2 lithium, for example) is usually safe. To switch grease types cleanly, empty the current grease completely, solvent-flush the barrel and head with mineral spirits, dry thoroughly, lightly re-grease the plunger rod seal with a compatible grease, then reload with a single grease type. Workshops servicing mixed fleets should keep one dedicated gun per grease type, each clearly labeled.

How often should I clean a lever grease gun?

The S-707DC needs three maintenance activities at different cadences: an external wipe-down of the coupler and head after every use (to keep grit out), a deep clean of the barrel and follower plate every 3-6 months under continuous professional use, and an annual disassembly with seal inspection. For a deep clean, unscrew the head, remove the cartridge or bulk grease, and wipe the barrel interior with a solvent-dampened rag. Inspect the follower plate for wear, check the plunger rod seal, solvent-clean the head and check valve, then reassemble with fresh grease on the plunger rod seal. Workshops running 10+ reloads per shift should clean every 90 days. Occasional use (weekly or less) can go 12 months between deep cleans. Replace worn seals from the STAR spare parts kit.

How should I store my grease gun?

Storage method on the S-707DC depends on duration. For daily storage, hang the gun vertically head-up with a loaded cartridge and the lever backed off to release residual pressure. For storage over 30 days, clean external grease from the coupler and hose, back off the lever completely, keep a cartridge loaded to prevent air ingress through the seals, and store in a dry location between 10-30°C away from direct sunlight (which degrades the hose and seals). Avoid temperature extremes that separate grease oils from the soap base. After any stretch longer than 30 days, pump 3-5 strokes to waste before greasing actual fittings to clear oxidized grease or separated oil at the head. For year-plus storage, drain the gun completely, clean it, and store dry with the plunger rod seal lightly greased.

Can a grease gun cause injury?

Yes, at 6,000 PSI (413 bar) the S-707DC produces enough pressure to cause grease injection injury if grease contacts skin through a wound or hose pinhole. Operators should wear wraparound safety glasses, nitrile gloves, closed-toe shoes, and long sleeves when working at face height. A few safety rules are non-negotiable. Never point the coupler or hose at any part of your body, and keep hands behind the coupler rather than in front. Inspect the 12 inch flexible hose before each use for cracks, bulges, or stiffness that signal an imminent burst, and never test the gun by pressing the coupler against skin or fabric. If injection does occur (a small puncture with pale waxy skin around it), treat it as a surgical emergency and go to hospital immediately. Injected grease does not absorb and requires surgical removal within hours to prevent tissue damage.

What is the difference between 6,000 PSI and 10,000 PSI grease guns?

6,000 PSI guns (like the S-707DC) are the standard for automotive, agricultural, and general workshop use; 10,000+ PSI guns are specialized industrial tools for heavy equipment with crusted zerks or sealed bearings. The 6,000 PSI level clears 85 percent of working fittings at lower operator fatigue and safer pressure margin for seals and hoses. 10,000+ PSI guns (S-707 at 12,000 PSI) are needed for construction equipment, mining machinery, and 20+ ton excavators where grease fittings are routinely neglected or exposed to heavy contamination. Trade-off: higher pressure guns stress component ratings (head seals, barrel wall, hose crimps, coupler), shortening service life if used daily below the pressure threshold.

What does 0.049 inch (1.2mm) barrel wall thickness mean?

0.049 inch (1.2 mm) is the wall thickness of the cold-drawn steel barrel on the S-707DC, which determines burst pressure rating, corrosion margin, and structural rigidity under sustained 6,000 PSI operation. Cold-drawn steel at 1.2 mm delivers roughly 4x safety margin on 6,000 PSI operating pressure, meaning actual burst pressure exceeds 24,000 PSI. Thinner-wall barrels of 0.035 inch / 0.9 mm, often seen on commodity lever guns, reduce that to 2x safety margin and raise the risk of failure under cold-weather stress or drop impact. The 1.2 mm spec also provides corrosion margin for humid storage environments and enough structural rigidity that the barrel does not deform under grip force during aggressive lever pumping. Thick-wall cold-drawn steel is the durability spec that separates professional-tier lever guns from commodity alternatives.