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319-0678 Actuator Pump Small Flange 31-Tooth With Transfer Pump – HEUI High-Pressure Oil Pump For CAT C7 / C9 Diesel Engines | OEM Replacement & Rebuild Part
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319-0678 Actuator Pump Small Flange 31-Tooth With Transfer Pump – HEUI High-Pressure Oil Pump For CAT C7 / C9 Diesel Engines | OEM Replacement & Rebuild Part

319-0678 Actuator Pump Small Flange 31-Tooth With Transfer Pump – HEUI High-Pressure Oil Pump For CAT C7 / C9 Diesel Engines | OEM Replacement & Rebuild Part

1. Product:319-0678
2. Compatible Equipment: Diesel Fuel Injection Systems
3. Manufacturer: Aftermarket OEM Replacement
4. Condition: Brand New, Fully Tested
5. Origin: ABOSEDE Diesel
6. Shipping period: 3-5 business days
7. Payment terms: T/T, Western Union, PayPal

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Product Introduction

When a CAT C7 or C9 diesel engine refuses to start on a freezing morning, or suddenly loses power under load, the culprit is frequently overlooked: the hydraulic actuation circuit's pressure source. The 319-0678 Actuator Pump​ is not just a simple fuel accessory; it is the high-pressure oil supply heart of the HEUI (Hydraulically Actuated Electronic Unit Injection) system. From the perspective of diagnostic troubleshooting, this small flange, 31-tooth pump with an integrated transfer pump serves as the foundational pressure generator that allows the ECM to command injector firing events. Without its precise oil pressure output, the injectors remain dormant, regardless of how perfectly the fuel side is primed.

 

🔩 The 31-Tooth Small Flange: A Precision Timing Interface

 

Looking closer at the mechanical interface, the "Small Flange" designation is critical for parts correct identification. This pump utilizes a 31-tooth drive gear​ designed to mesh seamlessly with the engine's rear gear train (specifically engaging with the idler and crankshaft gears). For the diesel mechanic, this tooth count is a non-negotiable fitment check. Installing a large flange variant (different tooth count or spline pattern) results in improper gear mesh backlash-typically required to be within 0.15–0.25 mm (0.006–0.010 inch)-leading to rapid gear tooth shear or timing deviation. The 31-tooth configuration ensures the pump rotates at exactly half crankshaft speed, synchronizing the high-pressure oil pulses perfectly with the engine's combustion cycles.

 

⚙️ Integrated Transfer Pump: The Unsung Priming Hero

 

Mounted co-axially on the rear of the actuator pump housing is the low-pressure transfer pump (lift pump). Shifting the angle to fluid dynamics, this component is responsible for drawing diesel fuel from the tank and pushing it through the primary fuel filters to the heads, typically maintaining a supply pressure between 35 to 75 PSI (2.4 to 5.2 bar). Unlike standalone external lift pumps, this integrated design reduces potential leak points and ensures the HEUI pump's internal lubrication is maintained by the diesel fuel itself. A weakening transfer pump often precedes total actuation pump failure, manifesting initially as extended cranking times or intermittent power loss when the fuel filter becomes slightly clogged.

 

🚜 Application Scope Across Industries

 

Broadening the view to fleet management, the 319-0678 is the standardized HEUI pump for a massive range of Caterpillar equipment powered by C7 and C9 platforms. This includes CAT 320D/323D Excavators, 814F II/816F II Compactors, D6R/D6T/D7R Track-Type Tractors, C9 Generator Sets, and various Marine Propulsion packages. It is also cross-referenced with the service part number 10R-8900. For procurement specialists, stocking the 319-0678 covers a vast portion of mid-size yellow iron fleets, making it a high-turnover, critical inventory item for any diesel parts distributor targeting the construction, forestry, or power generation sectors.

 

 

❓ Frequently Asked Questions (FAQ)

 

Q1: Does the 319-0678 include the fuel lift pump, or is that a separate purchase?​

A: The lift (transfer) pump is fully integrated into the 319-0678 assembly. It is driven directly via the internal gear train connected to the 31-tooth actuator flange, so no separate pump or mounting bracket is required.

Q2: Can I use this actuator pump on both mechanical and HEUI/Common Rail C7/C9 engines?​

A: While the physical mounting and flange drive are often shared, the internal actuator calibration may differ. Always verify your engine serial number prefix and fuel system type (Mechanical vs. Common Rail) against the OEM compatibility chart before ordering.

Q3: What is the recommended torque specification for the flange mounting bolts?​

A: Typically, Caterpillar specifies a torque range of 24–26 N·m (18–19 lb-ft)​ for the actuator pump mounting bolts, but you should always consult the specific engine service manualfor your C7/C9 serial number range to account for engineering updates.

Q4: How can I tell if my existing 319-0678 pump has a worn 31-tooth flange?​

A: Remove the pump and visually inspect the spline teeth for rounding, shiny spots (indicating slip), or debris embedded in the gear teeth. Any noticeable wear on the teeth edges usually means the drive coupling is compromised, risking timing drift.

Q5: Is it necessary to prime the lift pump side before starting the engine after installation?​

A: Yes. We recommend filling the fuel filter and loosening the outlet banjo bolt (or using the primer hand-pump if equipped) to bleed air until pure diesel flows. This prevents dry-starting the gear pump, which can accelerate wear on the internal gears.

 

Basic Information about the Company

 

202510091606539026

 

 

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