CAT 4DNX27GS1 Pump – 2.7 GPM, 3,000 PSI, 3/4" Shaft

Professional Triplex Pump for Reliable Pressure Washer Performance

The CAT 4DNX27GS1 Pump (Bare Pump Part #85.110.030) is a high-performance triplex direct-drive gas pump engineered for durability, precision, and efficiency. Delivering up to 3,000 PSI at 2.7 GPM, this pump is designed for contractors, commercial operators, and dedicated homeowners who demand professional-grade cleaning power.

Built by CAT Pumps, one of the most trusted names in the pressure washer industry, the 4DNX27GS1 features ceramic plungers, a brass manifold, and a built-in unloader for extended service life and consistent results. Packaged boxed and backed by CAT’s 5-year warranty, this pump is a long-term solution for restoring or upgrading your gas-powered pressure washer.

Key Features

• Bare Pump Part #: 85.110.030

• Pump Manufacturer: CAT

• Pump Model: 4DNX27GS1

• Pump Style: Triplex, direct-drive gas

• Max PSI: 3,000

• Max GPM: 2.7

• Shaft Size: 3/4"

• Unloader Type: Built-in

• Plunger (Piston): Ceramic for maximum durability

• Inlet Size: 3/4" GHF (garden hose fitting)

• Discharge Size: 3/8" Brass QC (85.300.103)

• Soap Injector: Fixed, integrated for detergent application

• Manifold Type: Brass for long-lasting strength

• RPM: 3,450

• Max Inlet Temp: 60°C / 140°F

• Thermal Relief Valve: 85.300.022 included

• Oil Capacity: 8.5 oz

• Oil Type: 30W non-detergent oil

• Weight: 11 lbs

• Warranty: 5 Years

Engineered for Professional Power

The 4DNX27GS1 is designed with CAT’s legendary triplex plunger system, which uses three precision ceramic plungers to deliver smoother performance, higher efficiency, and longer service life compared to axial cam pumps. This design reduces vibration, improves sealing, and ensures consistent pressure delivery.

With a maximum output of 3,000 PSI at 2.7 GPM, this pump has the right combination of power and flow for tough cleaning jobs. From removing oil stains on concrete to cleaning fleet vehicles and heavy equipment, the 4DNX27GS1 provides the professional-level results that CAT pumps are known for.

The ceramic plungers resist heat and wear for maximum longevity, while the brass manifold delivers strength and corrosion resistance, even in demanding environments.

Convenience and Built-In Features

The pump includes a built-in unloader, simplifying installation and operation while ensuring smooth pressure regulation. This eliminates the need for additional external unloaders, reducing setup complexity.

A fixed soap injector is integrated for detergent application, making it easy to apply cleaning chemicals when using low-pressure nozzles. This function enhances versatility for jobs that require soap or degreasers.

The brass quick-connect discharge fitting (3/8”) provides secure, reliable connections to hoses and accessories, minimizing leaks and ensuring quick setup.

Protection and Maintenance

The 4DNX27GS1 is built with protective features to help extend its lifespan. It comes with a thermal relief valve (85.300.022) that automatically releases overheated water during extended bypass operation, preventing damage to seals and components.

The pump requires 8.5 oz of 30W non-detergent oil to keep moving parts properly lubricated. Routine oil checks and changes are simple and cost-effective, ensuring long-term reliability.

With a maximum inlet temperature of 140°F (60°C), the pump can handle higher water input temperatures than many comparable models, providing added flexibility for different job site conditions.

At 11 lbs, the pump is built to be rugged yet manageable for installation and maintenance.

Common Applications

The CAT 4DNX27GS1 Pump is a versatile, professional-grade solution for a variety of pressure washer applications. Its high PSI rating and triplex design make it suitable for both residential power users and commercial operators. Typical uses include:

• Concrete and Driveway Cleaning – Blast away oil stains, dirt, and grime.

• Fleet and Vehicle Washing – Clean cars, trucks, trailers, and RVs.

• Agricultural Equipment – Maintain tractors, tools, and farm machinery.

• Construction Sites – Wash down heavy equipment and prep surfaces.

• Property Maintenance – Restore siding, brick, and outdoor furniture.

Its 3/4” shaft size ensures compatibility with many popular gas-powered engines, making it an ideal replacement pump for higher-end residential and commercial-grade washers.

Product Specifications

• Part #: 85.110.030

• Manufacturer: CAT

• Model: 4DNX27GS1

• Style: Triplex, direct-drive gas

• Max Pressure: 3,000 PSI

• Max Flow Rate: 2.7 GPM

• Shaft Size: 3/4”

• RPM: 3,450

• Unloader: Built-in

• Soap Injector: Fixed

• Manifold Material: Brass

• Plunger Material: Ceramic

• Inlet Connection: 3/4” GHF

• Discharge Connection: Brass QC 3/8" (85.300.103)

• Oil Capacity: 8.5 oz (30W non-detergent oil)

• Thermal Relief Valve: 85.300.022

• Max Inlet Temp: 60°C / 140°F

• Weight: 11 lbs

• Warranty: 5 Years

Backed by CAT Pumps’ Reputation

For decades, CAT Pumps has been the industry standard for durability, precision, and long service life. The 4DNX27GS1 Pump continues this tradition, offering a triplex design, ceramic plungers, and brass manifold for professional-grade reliability.

Backed by a 5-year warranty, this pump provides exceptional long-term value and peace of mind, making it a top choice for contractors and homeowners alike.

When you need dependable cleaning power and unmatched durability, the CAT 4DNX27GS1 Pump is the professional’s choice—engineered for performance, built to last.