Biswing Pressure Washer Pump 7/8" Shaft Replacement — 3400 PSI, 2.5 GPM Front Inlet

The Biswing pressure washer pump is a direct-replacement vertical plunger pump rated up to 3400 PSI and 2.5 GPM for gas-powered washers with a 7/8" shaft.

Designed as a robust replacement for common gas pressure washers, this Biswing pump pairs a durable aluminum-alloy body with a vertical plunger design to restore strong water pressure for outdoor cleaning jobs. It accepts a front 3/4" NH garden hose inlet and an M22 threaded high-pressure outlet, fits many 6.5–7 HP (180–225 cc) engines with a 7/8" shaft, and includes a thermal relief to protect the pump from heat build-up. The package ships with mounting hardware, detergent hose, and shaft keys for a complete swap.

Will this pump fit my pressure washer engine?

Check your engine shaft and connection types before ordering: the Biswing pump is built for a 7/8" drive shaft and horizontal engines that use a vertical pump orientation. It uses a 3/4" NH garden hose inlet and an M22 high-pressure outlet.

• Fits engines with a 7/8" horizontal shaft (confirm diameter before purchase).
• Ideal for 6.5–7 HP (180–225 cc) gas engines.
• Front inlet: 3/4" NH garden hose thread for water supply.
• High-pressure outlet: M22 14 male thread for hose connection.

How does the pump protect itself from overheating and wear?

The Biswing pump includes a built-in thermal relief valve to vent excess heat and pressure, helping prevent overheating during prolonged use. Its aluminum alloy body resists corrosion and supports stable operation, while improved seals reduce oil and water leaks for longer service life.

• Thermal relief valve prevents damage from excess heat.
• Aluminum alloy housing offers corrosion resistance and rigidity.
• Durable seals designed to minimize oil/water intrusion and wear.
• One-piece pump design reduces failure points compared with multi-piece units.

What performance can I expect for cleaning tasks?

Rated up to 3400 PSI and 2.5 GPM, this pump restores strong, steady pressure for common outdoor cleaning needs such as driveways, decks, siding, vehicles, and patio furniture. Actual performance depends on your engine power and nozzle selection.

• Maximum working pressure: 3400 PSI for tougher tasks.
• Flow rate: 2.5 GPM for efficient rinsing and detergent use.
• Pair with appropriate nozzles to adjust spray angle and force.
• Cold water use only — not designed for hot-water applications.

What comes in the box and how easy is installation?

The package contains the replacement pump plus installation essentials to simplify swapping the unit into most compatible washers. Basic mechanical skills and the correct adapters (if needed) make installation straightforward.

• Included: 1 pump, 1 detergent hose, 3 M8×60 bolts, 3 M8 locknuts, 3 M8 flat pads.
• Included shaft keys: two sizes to match common shaft keyways (4.78×4.78×35/42).
• May require a separate adapter coupler if hose fittings differ.
• Designed for cold-water systems; follow torque and alignment guidelines when mounting.

Who is this for: The Biswing 3400 PSI replacement pump suits DIYers, maintenance pros, and small contractors who need to replace a worn pump on gas-powered pressure washers that use a 7/8" shaft and front inlet/outlet configuration. It’s aimed at users who want a rugged, affordable pump with common fittings and added thermal protection—ideal for restoring cleaning power on residential and light commercial machines. Ensure your engine specs and hose threads match before purchase to guarantee compatibility.