S-704 Lever Action Grease Gun

Frequently Asked Questions: Lever Action Grease Gun 10 oz.

What is a 10 oz. lever action grease gun used for?

A 10 oz. lever action grease gun is a mid-capacity manual lubrication tool used for greasing chassis joints, bearings, U-joints, ball joints and zerk fittings on vehicles and equipment where mini guns run out too quickly but full-size 14 oz. guns are unnecessarily bulky. The S-704 delivers 6,000 PSI with 300 cc bulk capacity, covering approximately 20-25 typical chassis fittings per load. Ideal for automotive workshops, light agricultural service, fleet maintenance, mobile mechanics and general workshop use.

How much pressure does the S-704 develop?

The S-704 develops up to 6,000 PSI (413 bar), which is pro-grade pressure for a bulk-fill lever grease gun. This forces grease through crusted zerk fittings, sealed bearings, and tight clearance joints that lower-pressure guns cannot service. For heavy industrial applications requiring 10,000-12,000 PSI (construction, mining, heavy equipment), step up to the S-707. For most automotive, agricultural and light industrial fittings, 6,000 PSI is more than sufficient.

How much grease does the S-704 deliver per stroke?

The S-704 delivers 0.55 grams of grease per stroke, or 1 oz. (22 grams) per 40 strokes. At full 300 cc capacity, the gun holds approximately 545 strokes of grease before reloading. For service planning: typical chassis fitting = 3-5 strokes. Ball joint = 2-4 strokes. Sealed bearing via zerk = 10-15 strokes; U-joint = 5-8 strokes. Count strokes to match equipment service manual specifications.

How do I bulk-load a 10 oz. lever action grease gun?

To bulk-load the S-704. Unscrew the demountable bottom cap. Next, retract the plunger rod fully and lock it in the side slot. Then, dip the open 50.80 mm barrel into a grease pail pressing downward. After that, slowly release the plunger rod so grease flows into the 300 cc barrel without trapping air pockets. Finally, wipe threads clean and reattach the head. The wider 50.80 mm barrel fills faster than narrow mini guns. Alternatively, use suction fill by submerging the head outlet in grease and retracting the plunger to draw grease through the head.

How do I prime the S-704 after loading?

After loading, pump the lever 3-5 times. Grease should flow from the coupler within 5-8 strokes. If grease does not flow: loosen the aluminium head 1/4 turn while pumping slowly, air will escape through the loosened threads followed by a bead of grease confirming the prime is clear, then retighten. The extra-heavy follower spring applies constant pressure on the grease column, which keeps priming fast. If priming fails after bleeding, the barrel has an air pocket. Disassemble, pack grease manually against the follower plate, reassemble and re-prime.

Can I use the S-704 on U-joints and ball joints?

Yes, U-joints and ball joints are primary applications for the S-704. U-joints typically need 5-8 strokes until fresh grease appears at all four bearing caps. Ball joints need 2-4 strokes until fresh grease shows at the boot seal. Stop immediately when fresh grease appears to avoid blowing the rubber boot. The 6,000 PSI pressure handles crusted fittings on older vehicles where lower-pressure guns stall. Use NLGI 2 lithium or moly-fortified grease for U-joints under heavy load.

Can I use a lever action grease gun for fifth wheel hitch lubrication?

Yes, the S-704 works for greasing fifth wheel hitch pivot points, locking jaws, and kingpin bushings that have zerk fittings. For the fifth wheel plate surface itself, apply grease directly by hand or with a brush (not through the gun). The 10 oz. capacity is practical for a complete fifth wheel service including all pivot zerks, release handle pivots, and slider rail fittings. Use NLGI 2 lithium EP grease for fifth wheel applications.

Can a lever action grease gun handle high-viscosity grease?

Yes, the S-704's 6,000 PSI pressure handles NLGI 2 and NLGI 3 grease without difficulty. NLGI 3 (stiff, high-temperature grease) requires more lever effort per stroke but the mechanical advantage of the lever design compensates. For very cold conditions where NLGI 2 becomes too stiff to pump, switch to NLGI 1 grease or warm the gun to at least 10°C before use. The extra-heavy follower spring maintains positive contact with stiff grease that would defeat weaker springs.

Why is my lever action grease gun air locked after bulk filling?

Air lock happens when air enters the barrel during bulk loading, creating a pocket between the grease and the pump chamber that prevents priming. To fix on the S-704. Loosen the head 1/4 turn while pumping slowly until grease oozes out, then retighten. Next, if that fails, disassemble via the demountable bottom cap, manually pack grease against the follower plate to eliminate the air pocket, reassemble and re-prime. Prevent recurrence by releasing the plunger rod slowly during bulk loading and tapping the gun on a bench after loading to settle grease against the follower.

Does the grease gun leak when stored on its side?

No, a properly assembled S-704 does not leak when stored horizontally. The machined non-return valve prevents grease from flowing backward through the head, and the follower plate seal prevents leakage from the barrel end. If you notice leaking. Check the head is fully threaded tight. Next, inspect the non-return valve for debris. Then, check the follower plate seal for wear. Horizontal storage is actually recommended over vertical to prevent oil bleed (grease oil separating from the thickener over time).

Can you mix different types of grease in one gun?

No. Different grease thickeners (lithium, calcium, aluminum complex, polyurea, clay) can react chemically and form hard deposits that clog the S-704 and degrade lubrication. NLGI grade mixing within the same thickener family (e.g. NLGI 1 and NLGI 2 lithium) is generally safe. Thickener-chemistry mixing is not. To switch types: empty residual grease via the demountable bottom cap, solvent-flush the barrel and head, dry completely, lightly re-grease seals, reassemble and load new grease.

How do I clean a lever action grease gun when switching grease types?

To flush the S-704. Pump out remaining grease through the coupler 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 compatible with 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. Full flush is required before switching thickener types.

How should I store a 10 oz. lever action grease gun?

Store the S-704 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). Disengaging the plunger releases follower spring tension, extending spring life over long storage. For storage over 3 months: wipe exterior, remove the coupler, cap the outlet. Avoid hot storage above 40°C which accelerates seal aging and grease hardening in the barrel.

Can a grease gun cause serious injection injury?

Yes. A 6,000 PSI grease injection injury is a medical emergency: grease injected under the skin spreads along tissue planes and can cause severe damage, chemical burn, infection and amputation even from a tiny puncture wound. Always wear safety glasses and nitrile gloves. Never place your hand or body in front of the coupler tip or a pressurized hose. If injection happens, go to an emergency room immediately and tell staff it is a high-pressure grease injection injury. Inspect the 12 inch flexible hose before every use for cracks, bulges or kinks.