CAT D8R / D8N Main Hydraulic Pump – China Remanufactured (139-4151 / 1394151)

Description

Detail Information

Note: The application information provided is for reference only. Please confirm the part number and compare it with the old component before purchasing. If you have any questions, please feel free to contact us.
It is worth choosing a product that features stable performance, high reliability, easy installation, and quick response.

1. Key Features & Benefits

• Precision-remanufactured to Caterpillar OEM standards – This main hydraulic piston pump (OEM 139-4151 / 1394151, also known as A4VG125 series) has been fully disassembled, cleaned, crack-inspected, and rebuilt to meet Caterpillar’s original equipment specifications. Every critical component – cylinder block, piston assemblies, valve plate, swashplate, bearings, and seals – is either renewed or replaced with new, high-quality parts. The result is restored hydraulic performance at a fraction of the cost of a new genuine pump.

• Direct replacement for CAT D8R and D8N bulldozers – Specifically engineered for Caterpillar D8R, D8R II, D8N, D8GC, and D8 GC track-type tractors. This pump is the heart of the dozer’s hydraulic system, powering the blade lift, tilt, ripper, and steering functions. Also compatible with related models using the same A4VG pump platform.

• High-pressure capability for heavy dozing work – Rated pressure is typically around 350 – 400 bar (35 – 40 MPa / ≈5,076 – 5,800 psi) . The pump can withstand short-term peak pressures up to 450 bar (45 MPa / ≈6,526 psi) , allowing it to handle sudden high-load situations during heavy-duty operations such as pushing through extremely hard soil or rock. The D8R hydraulic system operates at a relief valve pressure of 3,500 psi (≈241 bar) with a pump flow capacity of 79 gpm (≈299 L/min) .

• Proven A4VG125 axial piston design – Based on the reliable A4VG125 platform, this variable displacement axial piston pump delivers smooth, powerful operation for functions like raising and lowering the bulldozer blade, tilting it, and operating the ripper attachment. The pump is built with high-strength materials and precision-machined components for exceptional durability in the most demanding earthmoving conditions.

• Restored dozer hydraulic power – After remanufacturing, this pump delivers the full rated flow and pressure your D8R or D8N was designed for. Your bulldozer regains original blade response, ripping force, and steering control – eliminating the sluggish performance caused by internal wear and leakage.

• Direct bolt-on replacement – Mounting flange, drive shaft spline, and hydraulic port configurations are restored to original Caterpillar specifications. No modifications, no adapters – your mechanic unbolts the old pump and bolts this one in.

• Heavy-duty construction for extreme conditions – Built with a robust, reinforced structural design that ensures stable high-pressure output even under extreme loads. Hardened alloy steel and special coating technology resist wear and particle erosion, prolonging service life.

• Pre-shipment visual verification – Before packing, we send you detailed high-resolution photographs of the actual unit (mounting flange, splines, port threads, castings, overall condition). You approve shipment – we never ship blind.

• Fast delivery – 5–8 working days lead time from our Guangzhou warehouse. Monthly supply capacity of 300 units, available for single-piece or bulk orders.

2. Applications

The remanufactured CAT 139-4151 main hydraulic pump is the power source for D8R and D8N bulldozers used in the most demanding earthmoving operations:

• Heavy earthmoving & land clearing – D8R dozers are the backbone of large-scale site preparation, land clearing, and overburden removal. The pump’s high-pressure capability (350–400 bar continuous, 450 bar peak) delivers consistent blade force and ripping power hour after hour in the toughest materials. The 79 gpm flow rate ensures fast blade response and efficient cycle times.

• Mining & quarry support – Stockpile management, road maintenance, and bench preparation in open-pit mines and quarries. The pump’s robust construction and contamination-resistant design withstand abrasive dust and extreme conditions. The A4VG125 platform is proven in the most demanding mining environments.

• Large-scale construction & infrastructure – Highway construction, dam building, airport runway grading, and large-scale earthmoving projects. The pump’s consistent pressure output (3,500 psi relief) maintains stable power for blade and ripper operations, even under varying load conditions.

• Forestry & land management – Clearing vegetation, pushing fallen timber, and firebreak construction. The pump’s smooth, responsive control allows operators to position the blade precisely in tight conditions.

• Equipment rental fleet – D8R dozers are high-value rental assets. A remanufactured pump offers predictable performance at a cost that makes proactive replacement financially sensible – avoiding costly mid-rental failures, towing bills, and customer complaints.

• Pipeline & utility projects – Trench backfilling, right-of-way clearing, and access road construction. The pump’s reliable hydraulic output ensures consistent performance across long shifts in remote locations.

3. Maintenance Tips – Extend the Life of Your Remanufactured Pump

A properly installed and maintained hydraulic pump can deliver years of reliable service. Follow these tips to protect your investment:

• Replace hydraulic filters on schedule – Contaminated oil is the #1 killer of hydraulic pumps. Use genuine or high-quality filters and change them at Caterpillar-recommended intervals. A clogged or bypassing filter allows debris to score the cylinder block and valve plate.

• Keep oil clean and at the correct viscosity – Use the hydraulic fluid recommended by Caterpillar for your D8R. Water contamination degrades oil and causes internal rust. Have your oil analysed annually, especially if the machine operates in wet or humid conditions.

• Warm up the pump before heavy work – Run the engine at low idle for 3–5 minutes, then cycle all hydraulic functions slowly without load. This allows oil to reach all internal components and prevents cavitation damage, which is especially important in cold weather.

• Monitor system pressure – Regularly check that the main relief valve is set to the correct pressure (3,500 psi for D8R). Excessive pressure puts unnecessary strain on the pump and can cause premature failure.

• Listen for unusual noises – Knocking, whining, or squealing from the pump area often indicates cavitation (starved suction), worn bearings, or loose mounting. Investigate immediately – continued operation will cause catastrophic failure.

• Check pump alignment – Misalignment between the pump and engine flywheel housing puts side load on the shaft, destroying bearings and the shaft seal. After any engine or pump removal, verify alignment with a dial indicator.

• Keep the case drain line clear – A kinked or blocked case drain line will cause back pressure inside the pump housing, blowing the shaft seal instantly. Inspect the line whenever you service the pump.

• Store spare pumps properly – Keep remanufactured pumps in their original wooden case, in a dry, clean environment. Rotate the shaft by hand every 6 months to redistribute internal lubricant.

• Use new O-rings and sealing washers – When installing a remanufactured pump, always replace all seals on hydraulic connections. Reused seals are the most common source of external leaks.

• Bleed air after installation – After fitting the pump, run the engine at low idle and slowly cycle each function (blade lift, tilt, ripper) several times to purge trapped air. Air in the system causes cavitation and noisy operation.

• Keep a service log – Record installation date, hours, oil changes, filter changes, and any unusual observations (noise, temperature, leakage). This helps you anticipate pump life, schedule preventive maintenance, and avoid unexpected downtime.

Critical installation tip for the 139-4151 remanufactured pump:
– Case priming is MANDATORY. You must fill the pump housing with clean hydraulic oil through the topmost case drain port before starting the engine. Starting a “dry” pump will cause immediate failure of internal components.
– The case drain line must be clear and unrestricted. A blocked or kinked case drain will build back pressure inside the pump housing and blow the shaft seal instantly on first startup.
– Before installing the remanufactured pump, flush the entire hydraulic system and replace all filters. Contaminants from a failed pump will destroy a remanufactured unit just as quickly as a new one – debris does not discriminate.
– Use new O-rings and sealing washers on every hydraulic connection. Reused seals guarantee leaks.
– After installation, run the engine at low idle for 2-3 minutes with the pump in neutral, then slowly cycle each function (blade lift, tilt, ripper, steering) to purge air from the system.
– Check pump alignment with the engine flywheel housing – misalignment causes premature bearing wear and shaft seal leakage.

Warranty note: Warranty period is 3 to 6 months depending on product details. We do not provide warranty service for original used or remanufactured parts. Our value is delivered up front: careful remanufacturing, thorough testing, and pre-shipment visual verification. For customers who require a warranty-covered option, we can quote new aftermarket units – ask our sales team.

The main hydraulic pump is the heart of your CAT D8R or D8N’s hydraulic system. Our remanufactured 139-4151 gives you restored dozer performance at a cost that keeps your budget intact – not with shortcuts, but with genuine factory-grade restoration. Send us your machine serial number – we will confirm compatibility and provide a quote within 24 hours.