Pressure Washer Pump 4200 PSI, 4.2 GPM, 1-Inch Shaft

Pressure washer pump replacement restores high-pressure cleaning power with up to 4200 PSI and 4.2 GPM for faster driveway, siding, deck, and equipment washdowns. Built as a horizontal triplex plunger pump with corrosion-resistant metal components and an adjustable pressure regulator, it helps you match output to the job while reducing wear during pauses. Designed for many horizontal-shaft gas pressure washers using a standard SAE bolt pattern.

• Delivers up to 4200 PSI max and 4.2 GPM max for quicker rinsing and stubborn grime removal


• Fits 1" (25.4 mm) horizontal engine shafts and standard SAE bolt pattern for wide pump swap compatibility


• Includes 5 quick-change spray nozzles to cover soap, rinse, and heavy-cleaning angles


• Adjusts pressure via built-in regulator to fine-tune output and drop to idle during short breaks


• Simplifies maintenance with an oil sight glass for fast checks without disassembly (cold water use only)

Swap out a worn pump instead of replacing the whole washer and get consistent pressure back for routine home cleaning or light industrial tasks. For longer service life, run at the recommended working pressure (3400 PSI) when full output isn’t needed and monitor oil condition through the integrated sight glass—oil changes are recommended every 60 hours. Confirm your current inlet/outlet fittings and engine orientation before purchase for a smooth install. Grab yours today and get back to productive cleaning.

• Pump type: Horizontal triplex plunger


• Max pressure / recommended: 4200 PSI / 3400 PSI


• Max flow rate: 4.2 GPM (16 L/min)


• Shaft diameter: 1" (25.4 mm)


• Inlet connector: 3/4" NH garden hose


• Outlet connector: 3/8" quick connect


• Compatible engine power: 13–15 HP


• Primary materials: Copper, aluminum


• Net weight: 21.38 lb (9.7 kg)


• Water type: Cold water only


• Included: Replacement pump kit + 5 nozzles