S-705 Lever Action Grease Gun

Frequently Asked Questions: Lever Action Grease Gun 15 oz.

What is the difference between a 1/2 inch piston grease gun and a standard lever gun?

The 1/2 inch (12.7 mm) piston in the S-705 displaces a larger volume of grease per stroke than the smaller pistons in mini and standard lever guns. At 1 oz. per 18 strokes (1.56 g/stroke), the S-705 delivers nearly three times the grease per stroke of a 0.55 g/stroke mini gun. For a tractor with 40 fittings averaging 3 grams each, this means approximately 75 total strokes to complete service versus 220 strokes on a mini. The trade-off is slightly more lever force per stroke and a larger overall gun size.

What PSI does the S-705 produce?

The S-705 produces up to 6,000 PSI (413 bar) of sustained pressure. This is standard pro-grade pressure for a bulk-fill lever grease gun, enough to force grease through crusted zerk fittings and most sealed bearings. It is not the 10,000-12,000 PSI range of the S-707 series, which means the S-705 is better suited for agricultural, fleet, and general workshop use where 6,000 PSI is sufficient. Any bearing lip seal can fail at 500 PSI, so technique and stroke count matter more than maximum gun pressure for seal protection.

How many strokes does it take to dispense 1 oz. from the S-705?

The S-705 dispenses 1 oz. (28 grams) of grease in approximately 18 strokes. That is 1.56 grams per stroke, nearly three times the 0.55 g/stroke output of mini lever guns and significantly above the typical 1.28 g/stroke of standard lever guns. Count strokes to match equipment service manual specifications: typical chassis fitting 2-3 strokes (3-5 g), U-joint 5-7 strokes (8-11 g), sealed bearing via zerk 6-10 strokes depending on hub size. Always stop when fresh grease appears at the fitting to avoid blowing seals.

How do you fill a lever action grease gun with bulk grease?

To bulk-fill the S-705. Unscrew the demountable bottom cap. Next, retract the plunger rod fully and lock it in the side slot. Then, dip the open 57.15 mm barrel into an open grease pail. After that, press downward while slowly releasing the plunger rod so grease flows into the 500 cc barrel without trapping air. Finally, wipe threads clean and reattach the head. The wider barrel fills quickly from standard 5 kg and 15 kg grease pails in 20-30 seconds. Alternatively use suction fill: submerge the head outlet in grease and slowly retract the plunger to draw grease through the head.

How do you know when a lever grease gun is fully primed?

A fully primed S-705 delivers a steady, continuous stream of fresh grease from the coupler tip with firm, consistent lever resistance on each stroke. Signs it is not fully primed: intermittent grease flow, air spitting from the coupler, soft lever feel, or streaks of air bubbles in the grease column. To confirm prime, disconnect the coupler and pump 3-5 strokes into a waste container. Fresh grease should appear on each stroke without interruption. If not, loosen the head 1/4 turn while pumping to release trapped air, then retighten.

Can I use a lever grease gun for farm equipment?

Yes, the S-705 is specifically sized for agricultural equipment service where many fittings per machine make the 1/2 inch piston's higher output advantageous. A typical 4-cylinder tractor has 20-40 chassis, 3-point hitch, and PTO drive fittings. A combine harvester has 80-120+ fittings. The S-705's 500 cc capacity handles a complete tractor service on one fill, and a smaller combine section on each fill. Use NLGI 2 multi-purpose grease for chassis joints, moly EP grease for high-load points like loader pivots.

Can I use a lever grease gun for wheel bearings?

For serviceable wheel bearings with zerk fittings, yes. For repacking exposed wheel bearings removed from the hub, hand-packing is the correct method, not gun-pumping. The S-705 works for truck and tractor wheel hub zerks that accept grease gun injection. Pump slowly (2-3 strokes at a time) and stop when fresh grease appears at the seal. Over-pumping can blow the rear seal and contaminate brake components. For Bearing Buddy style boat trailer caps, pump 1 stroke at a time watching the spring-loaded piston for movement.

Can I use a lever grease gun to adjust a dozer front idler?

Yes, but only for models where the idler tension is grease-adjusted through a dedicated zerk fitting on the track tensioner cylinder. The S-705's 6,000 PSI is typically sufficient for small and medium dozers. Larger dozers may require the 10,000-12,000 PSI of an S-707 class gun. Check the equipment service manual for the correct pressure specification and grease volume. Never force grease if the lever becomes excessively hard, this indicates a blocked passage or stuck tensioner that needs mechanical service.

How do I fix a lever grease gun that won't build pressure?

Pressure loss on the S-705 has four common causes: air lock in the barrel, worn plunger or head seals, loose head connection, or a failed non-return valve. Diagnostic order. Loosen the head 1/4 turn while pumping until grease flows, then retighten (fixes air lock). Next, confirm the head is fully threaded tight. Then, inspect the plunger rod seal and head o-rings for wear or damage. After that, check the machined non-return valve for debris. Replacement seals and components are available as STAR spare parts. Never force the lever if it goes limp.

Why does my lever grease gun keep losing its prime?

Repeated prime loss usually means air is entering the barrel between uses, or the follower plate seal is worn and grease is bypassing the piston. On the S-705. Check the head threads are fully tight after each refill. Next, inspect the follower plate seal for cuts or hardening (replace if worn). Then, confirm the bulk grease has not separated or dried in the barrel (flush and reload if separation visible). After that, store the gun horizontally with plunger disengaged to reduce air ingress. Prime loss is more common on guns stored for long periods than guns in daily use.

What NLGI grade grease works with a lever grease gun?

The S-705 handles NLGI grades 1, 2, and 3 effectively. NLGI 2 is the standard multi-purpose grade for automotive chassis, agricultural, and general industrial lubrication. NLGI 1 is softer (easier to pump in cold weather or for central lubrication systems). NLGI 3 is stiffer (better for high-temperature applications). Below -10°C, switch to NLGI 1 or synthetic low-temperature grease. Above 80°C, use NLGI 3 or specialized high-temp formulations. Never mix NLGI grades of different thickener chemistries.

How do you flush a grease gun when switching grease types?

To flush the S-705 when switching grease thickeners. Pump out remaining grease through the coupler onto waste material until the plunger is fully extended. Next, unscrew the demountable bottom cap. Then, wipe the barrel interior and head with clean rags. After that, flush with solvent matching the old grease (mineral spirits for lithium, kerosene for calcium, naphtha for polyurea). From there, dry completely with compressed air or paper towels. Finally, lightly re-grease the plunger seal and o-rings with fresh grease. And last, reassemble and load new grease. Never mix incompatible thickeners, they form hard deposits that clog the gun and damage bearings.

Should a grease gun be stored horizontally or vertically?

Store the S-705 horizontally (laying flat) with the plunger rod disengaged, in a clean dry area at 5-35°C. Horizontal storage prevents oil bleed (grease oil separating from the thickener over time). Vertical nozzle-down storage accelerates oil separation and can leave a grease-starved pump chamber. Disengaging the plunger releases follower spring tension, extending spring life over months of storage. For storage over 3 months, wipe the exterior, remove the coupler, cap the outlet, and cover the gun to prevent dust ingress.

How dangerous is a grease gun at 6,000 PSI?

A 6,000 PSI grease injection injury is a surgical emergency. Grease injected under the skin through a small puncture spreads along tendons and tissue planes, causing ischemia, chemical burn, infection, and potential amputation even when the entry wound appears minor. Always wear safety glasses and nitrile gloves. Never place a hand or body in front of the coupler tip or hose. Inspect the 12 inch flexible hose before every use for cracks, bulges, or kinks. A hose burst at 6,000 PSI can spray grease and rubber fragments. If injection occurs, go to an emergency room immediately and state it is a high-pressure grease injection injury. Small wounds hide extensive internal damage.