S-707 Lever Action Grease Gun - Steel Head (Super Value)

Frequently Asked Questions: Lever Action Grease Gun

What is a lever action grease gun used for?

A lever action grease gun is a two-handed manual lubrication tool used for greasing chassis joints, bearings, pivots and zerk fittings on vehicles, heavy equipment and industrial machinery. The lever mechanism provides the highest mechanical advantage of any manual grease gun design, generating up to 12,000 PSI pressure to force grease through crusted fittings that cheaper pistol grip guns cannot service. The S-707 is the full-size industrial workhorse: 14 oz. cartridge capacity (or 15 oz. bulk), drop-resistant steel head, and Quadra-Cut Precision Technology plunger. Ideal for fleet maintenance, construction, mining, agriculture and workshop use.

How much PSI does a lever action grease gun produce?

The S-707 develops up to 12,000 PSI (827 bar), which is heavy industrial pressure rating. Standard lever guns typically produce 6,000-8,000 PSI; economy pistol grip guns produce 3,000-4,000 PSI. The S-707's 12,000 PSI forces grease through sealed bearings, heavily crusted zerk fittings, large hub assemblies and fittings on heavy construction equipment. For mini form factor at similar pressures, the STAR S-701, S-702, S-703E and S-703S minis provide 6,000 PSI in compact bodies.

How much grease does a lever action grease gun deliver per stroke?

The S-707 delivers approximately 1 gram of grease per stroke, or 1 oz. (28 grams) per 28 strokes. This is about double the per-stroke output of mini lever guns (0.55 g/stroke), making it faster to deliver high volumes on equipment with many fittings. Count strokes to meter exact grams per service manual specification: typical chassis fittings need 3-5 strokes; heavy-duty wheel bearings may need 20-30 strokes. Over-pumping damages seals, so always stop when fresh grease appears at the fitting.

How do you load a cartridge into a lever action grease gun?

To load a 14 oz. cartridge into the S-707: (1) unscrew the barrel from the head, (2) pull the plunger rod fully back and lock it in the side slot, (3) remove any old cartridge, (4) insert the new cartridge open-end-first toward the head, (5) peel off the metal seal on the other end of the cartridge, (6) reattach the barrel to the head, (7) unlock the plunger rod from the side slot so the follower spring pushes against the cartridge. Prime by opening the bleeder valve and pumping the lever until grease flows.

How do I prime a lever grease gun using the air bleeder valve?

After loading a cartridge or bulk-filling the S-707, open the air bleeder valve on the drop-resistant steel head by loosening it 1-2 turns, then pump the lever 3-5 times until grease flows from the bleeder, then close the bleeder. Continue pumping the lever and grease should now flow from the coupler. The bleeder valve releases air that enters during cartridge changes or bulk loading, which is the most common cause of grease gun priming failure. The S-707's dedicated bleeder valve solves this problem that plagues cheaper grease guns.

Can I use the S-707 on construction and mining equipment?

Yes, the S-707 is a standard lubrication tool on construction, mining, quarry and heavy industrial equipment fleets. The 12,000 PSI pressure forces grease through heavily contaminated zerk fittings on excavators, loaders, graders, haul trucks, bulldozers, drilling rigs and crushing equipment. The 14 oz. capacity (or 15 oz. bulk-filled via the bulk loader nut) services approximately 60-80 chassis fittings per load, reducing reloading stops during multi-machine service routes. Steel drop-resistant head survives tool box drops and site conditions; aluminium-head mini guns are not rated for this duty cycle.

Can a lever action grease gun be used for wheel bearing packing?

Yes, the S-707's 12,000 PSI pressure is high enough to force grease fully into tapered roller bearings, sealed ball bearings and large hub assemblies on trailers, trucks, tractors and heavy equipment. For serviceable bearings with zerk fittings, connect the coupler and pump until fresh grease appears at the seal. For bearings removed from the hub, use the S-707 with a rigid steel extension to pump grease directly into the bearing race. Lower-pressure guns may struggle to force grease through heavy-duty bearings, so the S-707 is the industrial standard for bearing service.

Can I use a lever action grease gun on a tractor with 100+ grease fittings?

Yes, the S-707 is well-suited for large tractors, combines and heavy farm equipment with many grease fittings per service. The 14 oz. (or 15 oz. bulk) capacity and 1-gram-per-stroke output mean one loading services approximately 60-80 typical chassis fittings. For equipment with 100+ fittings, consider the STAR S-724 (24 oz.) or S-732 (32 oz.) heavy-duty lever guns to further reduce reloading time. Use a filler pump connected to a 15 kg or 18 kg grease pail for fastest workshop turnaround.

Why does my lever action grease gun lever suddenly go limp?

A suddenly limp lever usually means the gun has run out of grease, developed an air lock, or lost follower seal contact with the grease column. On the S-707: (1) check if the cartridge or bulk barrel is empty and needs reloading; (2) if grease remains, open the bleeder valve and re-prime; (3) if the lever stays limp after re-priming, inspect the follower seal for wear or the follower spring for permanent loss of tension. A limp lever should never be forced; forcing it can damage the pump mechanism. Spare follower springs and seals are available from STAR as service parts.

Why is my lever action grease gun not pumping grease?

The most common cause is an air lock between the grease and the pump chamber, which prevents the lever from moving grease into the coupler. To fix on the S-707: open the air bleeder valve on the steel head, pump the lever 3-5 times until grease flows from the bleeder, then close it. If air lock persists, check that the follower spring returns the plunger fully (worn springs cause poor priming); confirm the cartridge metal seal was fully peeled off before loading; check the head is fully threaded tight. Other causes: blocked coupler (disconnect and pump to test), damaged follower seal, or incompatible grease mixture causing thickener separation.

Can I switch between different grease types in the same grease gun?

Yes, but never mix incompatible grease thickeners without a thorough cleaning between. Lithium, calcium, aluminum complex, polyurea and clay thickeners can react chemically and form hard deposits that clog the gun and degrade lubrication. The S-707 handles NLGI 1, NLGI 2, and NLGI 3 grease grades effectively; NLGI 2 is the standard multi-purpose grade for automotive and general industrial use, NLGI 1 is better for cold weather or central lubrication systems, and NLGI 3 suits very high-temperature applications. To switch safely in the S-707: empty residual grease, remove the 14oz (14 oz. / 400 g) cartridge or bulk-drain the barrel, disassemble the head and pump tube, solvent-flush the interior, dry completely, lightly re-grease new o-rings with fresh grease, reassemble and load new grease. Workshops should keep separate labeled guns per grease type.

How do I service a grease gun after heavy fleet use?

Clean the S-707 every 6 months for occasional use, every 2-3 months for weekly professional use, or whenever you switch grease types. Disassemble the head from the barrel, wipe out old grease with a clean rag, flush with solvent if hardened, dry completely, lightly re-grease the plunger seal and o-rings, reassemble. Inspect the air bleeder valve and bulk loader nut for grease buildup during each cleaning. Regular cleaning prevents follower spring fatigue and keeps the non-return valve seating properly.

Should I store a grease gun horizontally or vertically, and with the plunger engaged?

Store the S-707 horizontally (laying flat) with the plunger rod disengaged (released, not locked back). Horizontal storage prevents oil bleed (oil separating from the thickener) that happens over time with nozzle-down vertical storage. Disengaging the plunger releases follower spring tension, which extends spring life over long storage. Store in a clean dry area between 5°C and 35°C. For storage over 3 months, wipe the exterior, remove the coupler, cap the outlet, and either keep a cartridge loaded (to protect the pump tube from air exposure) or drain and clean the gun completely.

What are the risks of 12000 PSI grease injection injury?

Always wear safety glasses and nitrile or leather gloves, and never place your hand or body in front of the coupler tip or a pressurized hose. A 12,000 PSI grease injection injury is a serious medical emergency: grease injected under the skin can cause severe tissue damage, infection or amputation even from a tiny entry wound. If injection happens, go to an emergency room immediately and tell staff it is a high-pressure grease injection injury; small wounds can hide extensive internal damage. Inspect the hose before every use for cracks, bulges or kinks; a hose burst at 12,000 PSI is dangerous. Never bypass the coupler by pressing the gun tip directly against skin or a bearing seal.