476-8769 31-Tooth Diesel Injection Pump With Transfer Pump For CAT C7 C9 Engine | Hydraulic Injector Pump Group

In the high-precision environment of a diesel common rail system, timing is everything. The 476-8769​ is not merely a camshaft gear; it is a critical synchronization hub that bridges mechanical timing with fuel delivery logistics. Specifically engineered for Caterpillar C9 diesel engines, this 31-tooth drive gear features an integrated mechanical fuel transfer (lift) pump, ensuring that the high-pressure common rail pump is fed with a consistent, air-free fuel supply under all operating conditions.

 

 

This component is a direct OEM-spec replacement designed for the rigorous demands of heavy-duty applications. It is primarily utilized in:

Engines:​ Caterpillar C9 Industrial, Marine, and GenSet configurations.

Machinery:​ Caterpillar 586C, 637G/D/E, D6R, D7R, and various excavators and earthmoving compressors (e.g., 814F, 815F, 816F).

Power Systems:​ XQP275, XQP300 generators, and SR4B alternators.

Whether you are an engine remanufacturer, a fleet maintenance manager, or an independent diesel technician, the 476-8769 offers the reliability required to keep mission-critical equipment operational.

 

 

Precision is non-negotiable in diesel valvetrains. The 476-8769 adheres to strict tolerances:

Part Number:​ 476-8769 (Cross-ref: CA476-8769, 4768769)

Tooth Count:​ 31 Teeth (Precision-ground helical/spur profile)

Integrated Function:​ Mechanical Fuel Transfer Pump (Lift Pump)

Drive Type:​ Keyed or Splined Camshaft Mount (depending on specific sub-model configuration)

Material:​ Hardened alloy steel for high wear resistance against timing idler gears.

Pressure Rating:​ Designed to maintain low-side fuel pressure (typically 25-40 PSI / 1.7-2.7 bar) to ensure the high-pressure common rail pump operates within its cavitation-free zone.

 

 

From a systems engineering perspective, the 476-8769 solves a packaging and synchronization challenge. By integrating the fuel lift pump directly onto the camshaft drive gear, Caterpillar eliminated the need for a separate accessory drive bracket.

Timing Synchronization:​ The 31-tooth count is calculated to maintain the exact 2:1 crankshaft-to-camshaft speed ratio required for 4-stroke diesel cycles, ensuring injectors fire and valves actuate at the precise millisecond required.

Fuel Logic:​ As the gear rotates, eccentric lobes on the unit actuate the integrated lift pump's diaphragm or piston. This ensures that fuel delivery to the common rail pump is proportional to engine RPM-higher revs equal higher fuel flow demand, which the gear-driven pump naturally meets without electronic control.

 

 

For the repair professional, recognizing the signs of a failing 476-8769 can prevent catastrophic downtime:

Fuel Starvation Symptoms:​ If the integrated lift pump vanes or check valves wear, the engine may crank but not start, or stall under high load because the common rail pump cannot build sufficient pressure.

Timing Issues:​ Worn gear teeth introduce "lash" or slack in the timing train. This results in a rattling noise from the front gear cover and can throw off injection timing, leading to excessive black smoke and reduced fuel economy.

Preventative Replacement:​ Whenever the front gear cover is removed for seal replacement or timing component access, inspecting the 476-8769 for chipped teeth or pump lever wear is recommended. Replacing a worn gear is significantly cheaper than repairing a jumped-time engine.

 

 

In modern diesel common rail systems, the high-pressure pump (HPP) is sensitive to inlet conditions. A failing or weak lift pump (like the one integrated into 476-8769) forces the HPP to work harder, creating cavitation that erodes the HPP's internal pistons and rollers. Using a high-spec 476-8769 replacement ensures the HPP receives fuel at the correct pressure and volume, directly extending the lifespan of your expensive Bosch or CAT common rail injection pump.

 

 

Before installing the 476-8769 31-tooth diesel pump, the surrounding diesel system should be inspected. Replacing the pump without checking contamination, oil quality, filters, seals, and related sensors can shorten service life.

Recommended checks:

◆ Confirm 476-8769 / 4768769 part number
◆ Confirm 31-tooth drive before installation
◆ Inspect diesel filter and oil filter condition
◆ Check for metal particles or sludge
◆ Replace damaged seals and gaskets
◆ Inspect wiring, connectors, and pressure sensors
◆ Avoid dry start after installation
◆ Follow service manual torque and timing procedures
◆ Test pressure behavior after the engine starts

A clean diesel system is the best protection for a new pump.

 

 

Q1: Can I use this 476-8769 gear if my C9 engine has an electric lift pump?

A: Generally, no. The C9 engine block is configured either for a gear-driven mechanical pump (using this 476-8769 gear) or an electric pump. If your setup requires the mechanical version, you must use this specific geared unit; using the wrong camshaft configuration will result in improper fuel delivery or interference issues.

Q2: Does the 31-tooth count differ between C7 and C9 engines?

A: While both engines share similarities, gear tooth counts, diameters, and timing offsets can vary. Always verify the specific part number 476-8769, as it is specifically machined for the C9's timing train geometry.

Q3: Is the fuel lift pump portion serviceable separately from the gear?

A: On the 476-8769 unit, the lift pump mechanism is integrated into the gear housing. It is typically sold and replaced as a single assembly to ensure the timing integrity and structural balance of the rotating mass.

Q4: What noise indicates a failing 476-8769 gear?

A: Listen for a rhythmic "whirring" or "grinding" from the timing cover area, distinct from the injector ticking. A "rattle" at idle that smooths out at higher RPM often indicates excessive gear lash or a worn idler gear meshing with this 31-tooth gear.

Q5: How does this gear affect diesel injection timing?

A: Indirectly. While the ECM controls the exact pulse of the injectors, this gear ensures the camshaft (which drives the fuel injectors' mechanical linkages in some configurations or simply maintains valve sync) is perfectly phased with the crankshaft. Incorrect installation of this gear will offset all valve and injection events.

Q6: Is this part susceptible to corrosion if the fuel has water content?

A: Yes. The internal components of the integrated lift pump can corrode if stagnant fuel with high water content is present. This is why maintaining fuel water separators is crucial for the longevity of the 476-8769.

 

 

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