S-708 Lever Action Grease Gun

Frequently Asked Questions: Lever Action Grease Gun

What is the difference between high output and high pressure grease guns?

The S-708 is a high-volume lever action grease gun with a 5/8 inch (15.87 mm) wide piston that delivers 2.4 grams of grease per stroke, double the output of standard 1 gram per stroke lever guns. The wider piston pushes more grease per pump cycle, meaning 1 oz. dispenses in 12 strokes instead of 28. This cuts greasing time roughly in half on heavy equipment with many fittings: tractors with 20-30 zerks, excavators with heavy pin grease requirements, and fleet maintenance routes. The 5/8" piston is the defining USP that separates the S-708 from the standard S-707 (1 g/stroke with narrower piston).

What is the flow rate of a lever action grease gun?

Yes. 6,000 PSI (413 bar) combined with the 5/8" wider piston delivers more grease volume at professional working pressure, ideal for heavy equipment fittings where volume matters more than extreme peak pressure. The wider piston design trades some peak pressure capacity for faster grease delivery. At 6,000 PSI the S-708 clears 85 percent of agricultural, fleet, and construction equipment zerks while servicing fittings 2X faster. For badly crusted zerks requiring 10,000-12,000 PSI pressure, use the steel-head S-707 (standard piston, higher PSI).

What is the grease output per minute of a lever grease gun?

The S-708 delivers 2.4 grams of grease per lever stroke, equivalent to 1 oz. per 12 strokes or a full 500 cc bulk barrel in approximately 208 strokes. This is more than double the standard lever gun output of 1 g/stroke (28 strokes per oz.). The wider 5/8" piston increases grease column volume per pump cycle. For service planning: typical chassis zerk takes 1-2 strokes (2.4-4.8 g), U-joint 2-3 strokes, wheel bearing 4-7 strokes, heavy equipment pin 6-10 strokes. Count strokes carefully to avoid over-greasing. The higher volume output increases risk of blowing bearing seals if not metered.

Can a lever grease gun use both cartridge and bulk grease?

The S-708 is optimized for bulk and suction loading only because the 5/8" wider piston requires an unobstructed grease column for consistent 2X volume delivery. Cartridge loading relies on a smaller-diameter inner sleeve that constrains the grease column. This is incompatible with the wider piston geometry. Filler pump loading works through a head port that is similarly incompatible. The 2-way design is intentional: bulk fill from 5 kg or 15 kg pails is the fastest and cheapest per-gram method for high-volume workshops (which is the S-708's target market), and suction fill works when bulk grease is not available.

How many pumps does it take to prime a lever grease gun?

Priming the S-708 after a reload is a short sequence. Fill the barrel via bulk dip or suction fill with the plunger rod fully retracted and locked in the side slot. Release the plunger rod so the follower spring applies pressure to the grease column. Loosen the head a quarter turn to open the air release path and pump the lever slowly 3-5 times until grease flows through the loosened joint. Retighten the head and give another 2-3 firm pumps to bring the gun to working pressure. Finally, connect the coupler and pump. Fresh grease should flow by the first stroke. The 5/8 inch wider piston creates more suction than standard guns during priming, so ensure the follower plate is fully seated on grease before you begin.

Can I use a lever action grease gun for my tractor?

Yes, tractor and agricultural equipment service is the primary use case for the S-708 2X volume design. A typical 100 HP tractor has 20-30 grease fittings per service (every 50-100 operating hours). At 2.4 g per stroke, the S-708 services a full chassis route in roughly half the strokes of a standard gun, reducing operator fatigue and wrist strain. Typical tractor greasing: front kingpins (2-3 strokes each at 2.4 g/stroke), tie rods (1-2 strokes), U-joints (3-4 strokes), PTO slip yokes (3-4 strokes), loader arm pins (4-6 strokes). One 500 cc bulk fill services approximately 3-4 tractors per load.

What is the best lever grease gun for heavy equipment maintenance?

Yes, excavators and compact track loaders benefit from the 2X volume output because their pin and bushing fittings accept 10-20 strokes of grease per service. At 2.4 g/stroke, 15 strokes delivers 36 g of grease per pin, typical excavator pin requirement. Using a standard 1 g/stroke gun would take 36 strokes for the same fill. On a 10-pin excavator boom/arm/bucket assembly, this saves 200+ strokes per service. For heaviest equipment with 25-ton+ class machines or severely crusted fittings, step up to the 12,000 PSI S-707 (standard piston with higher pressure rating).

Is a lever grease gun better than a pistol grip for extended use?

The 5/8" (15.87 mm) wide piston increases grease displacement per stroke from 1 g to 2.4 g, a 2.4X volume increase. This means: faster service routes (40-50 percent fewer strokes per fitting), reduced operator wrist strain, one bulk fill services more machines, and better suction fill performance (wider piston creates stronger vacuum for drawing grease from pails). Trade-offs: maximum sustained pressure drops from 12,000 PSI (standard) to 6,000 PSI because the wider piston spreads force over a larger area, and cartridge/filler pump loading is not supported. For equipment with 15+ fittings per service, the S-708 trade-off favors volume. For single-fitting service on crusted zerks, the standard S-707 is better.

How do blocked air vents cause grease gun leaks?

Air lock is cleared on the S-708 by loosening the head a quarter turn to open the air release path, pumping the lever slowly for 3-5 strokes until grease flows through the loosened joint, retightening the head, and resuming normal pumping. The 5/8 inch wider piston actually reduces air-lock frequency compared with standard guns because the larger surface area keeps better follower-plate contact with grease. If air lock persists after a bleed, inspect the follower plate for tilt or wear, check the plunger rod seal, and always refill the barrel completely before storage to prevent air ingress through seals. Air lock is the top priming failure mode on every lever gun. Prevention matters more than cure.

Why is the handle stiff but no grease comes out?

Pressure or delivery failure on the S-708 has four typical root causes: an air lock between grease and plunger (cleared by loosening the head), a worn plunger rod seal letting pressure bypass, a one-way check valve in the head stuck from debris, or an empty barrel with the plunger bottomed out. Troubleshoot in sequence. Start by bleeding the head a quarter turn and pumping until grease flows, then pull the plunger rod back to check whether grease remains in the barrel. If priming still fails after bleeding, unscrew the head and inspect the check valve for grease debris. Clean with solvent if needed. Only after the check valve is confirmed clean should you suspect the plunger rod seal and replace it from a STAR spare parts kit. The wider 5/8 inch piston requires slightly higher seal quality, so inspect every 12 months.

Can contaminated grease cause dispensing problems?

No. Mixing incompatible grease thickeners (lithium with calcium, lithium with polyurea, calcium with aluminium complex) causes a chemical reaction that forms hard deposits and clogs check valves. The S-708's wider piston and larger volume per stroke means any thickener incompatibility accumulates deposits faster than on a standard-piston gun. 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 barrel, solvent-flush 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 labeled gun per grease chemistry.

How long does a lever action grease gun last?

Clean the S-708 every 3-6 months for continuous professional use, or whenever you switch grease types. The higher volume output means more grease passes through the head and check valve per service, so mild wear accumulates slightly faster than on standard guns. Deep clean procedure: unscrew the head, wipe the barrel interior with solvent-dampened rag, inspect the follower plate, check the plunger rod seal, solvent-clean the head and check valve, reassemble with fresh grease on seals. Pay particular attention to the wider piston seal: its larger circumference means more surface area for debris to accumulate. Workshops with heavy daily use (10+ reloads per shift) should clean every 90 days.

Should I disengage the plunger before storing my lever grease gun?

Storage procedure depends on duration. For daily storage, hang the S-708 vertically head-up with a loaded barrel and the lever backed off. For storage over 30 days, clean external grease from the coupler and hose, back the lever off completely, keep the barrel loaded with grease to prevent air ingress, and store between 10-30°C in a dry location away from direct sunlight. The 5/8 inch wider piston seals better against stored grease than narrower pistons, so storage-related air lock is less common on the S-708. For year-plus storage, drain the barrel completely, clean it, and store dry with the plunger rod seal lightly greased. After long storage, pump 3-5 strokes to waste before servicing actual fittings to clear oxidized grease.

How do I prevent over-greasing with a lever action grease gun?

The S-708's higher 2.4 g-per-stroke output raises over-greasing risk because fewer strokes reach the target quantity. An inattentive operator can deliver 5-10 grams to a fitting that only needs 3-4 g, which damages bearing seals. Work by the equipment service manual specification (usually expressed in grams or ounces per fitting) and stop at the specified stroke count or when fresh grease first appears at the bearing seal. Never pump until the fitting refuses more grease. Overfilled fittings blow their seals. Think of the higher output as time saved per fitting, not extra grease per fitting. For bearings with small cavities (wheel bearings, tie rod ends), the standard 1 g-per-stroke S-707 gives finer metering.

Can a lever action grease gun cause a high pressure injection injury?

Yes, the S-708 develops 6,000 PSI (413 bar), enough pressure to cause grease injection injury if grease contacts skin through a wound or hose pinhole, and the 2X volume 5/8 inch piston pushes more grease per stroke if an accident happens. Operators should wear wraparound safety glasses, nitrile gloves, and closed-toe shoes. A few safety rules are non-negotiable. Never point the coupler or hose at any body part, and keep hands behind the coupler rather than in front. Inspect the 12 inch flexible hose before each use for cracks, bulges, or stiffness, and never press the coupler against skin or fabric to test. If grease injection does occur (a small puncture with pale waxy skin around the wound), treat it as a surgical emergency and go to hospital immediately. Injected grease does not absorb. It requires surgical removal within hours to prevent tissue damage.