CAT 3500666 (350-0666) Piston Pump | Fits 416E 422E 428E 434E Backhoe Loader

CAT 3500666 (350-0666) Piston Pump | Fits 416E 422E 428E 434E Backhoe Loader

Premium hydraulic piston pump designed as a direct OEM-compatible replacement for Caterpillar 416E, 422E, 428E, and 434E backhoe loaders. Built to deliver consistent hydraulic performance and long service life in demanding construction, utility, and municipal applications.

Product Highlights

• Part Number: 3500666 / 350-0666
• Direct Fit: No modifications required
• High Performance: Meets or exceeds original Caterpillar specifications
• Durable Construction: Precision-engineered for long service life
• Wide Application: Suitable for construction, utility, and municipal projects

Technical Specifications

• Part Number: 3500666 / 350-0666
• Product Type: Variable Displacement Piston Pump
• Brand Compatibility: Caterpillar (CAT)
• Application: Hydraulic System
• Warranty: 12 Months

Compatible Models

This piston pump fits the following Caterpillar backhoe loaders:

• Caterpillar 416E Backhoe Loader
• Caterpillar 422E Backhoe Loader
• Caterpillar 428E Backhoe Loader
• Caterpillar 434E Backhoe Loader

Applications

• Backhoe Loader Lift and Tilt Functions
• Backhoe Loader Dig and Swing Circuits
• Heavy-Duty Excavation and Loading Operations
• Construction, Utility, and Municipal Projects

Why Choose This Pump?

• Quality Guaranteed - Manufactured to meet OEM standards
• Ready to Ship - In stock and available for immediate dispatch
• Expert Support - Technical assistance available
• Competitive Pricing - Cost-effective alternative to dealer parts

Frequently Asked Questions

Q: What are the symptoms of a failing hydraulic piston pump on CAT 416E, 422E, 428E, or 434E backhoe loaders?
A: Common signs include slow or weak loader lift and tilt response, the backhoe dig function losing power or stalling under load, hydraulic oil overheating during normal operation, whining or knocking noise from the pump area, and visible hydraulic fluid leakage. Backhoe loaders perform dual functions — front loader and rear backhoe — so pump failure affects both loader bucket and digging arm performance simultaneously.

Q: Does the 3500666 fit all four backhoe loader models?
A: Yes, the 3500666 (350-0666) is designed as a direct OEM-compatible replacement for the CAT 416E, 422E, 428E, and 434E backhoe loaders. These models share the same pump mounting and hydraulic system architecture. Contact us with your backhoe serial number to confirm exact compatibility.

Q: What hydraulic functions does this pump support on a backhoe loader?
A: As the main hydraulic pump, it supplies flow to both front loader circuits (lift, tilt) and rear backhoe circuits (boom, stick, bucket, swing). It also supports auxiliary functions such as stabilizer legs and steering. A failing pump causes weak operation across all these functions — if only the loader or only the backhoe is affected, check for a control valve issue first.

Q: Should I flush the hydraulic system when replacing this pump?
A: Always. Flushing is essential — metal contaminants from the old pump can destroy the new pump within hours. Drain and replace all hydraulic oil, flush the system with clean oil, replace all filters, and refill with fresh Cat HYDO Advanced hydraulic oil. Backhoe loaders work in construction and utility applications where contamination risk is high — a thorough flush is critical.

Q: What type of hydraulic oil is recommended for these backhoe loaders?
A: Caterpillar specifies Cat HYDO Advanced 10W or 30W depending on operating temperature. Backhoe loaders perform varied tasks — digging, loading, lifting — and the hydraulic system operates under frequent load changes. Using non-CAT approved fluids can cause pump wear and void the warranty.

Q: How do I confirm this is the correct pump for my backhoe loader?
A: Check the part number on your current pump — if it reads 3500666 or 350-0666, this is the correct replacement. If the label is worn or missing, provide your backhoe serial number and we will verify compatibility before you order.

Q: Does this pump come with mounting hardware or gaskets included?
A: The pump is supplied as a complete unit. Depending on your backhoe configuration, you may need separate mounting bolts, gaskets, or O-rings. Contact us with your serial number and we will confirm exactly what is included and what additional parts you may need for installation.

Q: What is the warranty on this hydraulic piston pump?
A: This piston pump comes with a 12-month warranty covering manufacturing defects. The warranty does not cover damage caused by contaminated hydraulic oil, improper installation, failure to flush the hydraulic system, or using non-CAT approved hydraulic fluids.

Looking for this hydraulic pump? Contact us today for pricing, availability, and lead time information.

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