FAW Starter Motor: An Expert Guide to Its 5 Key Components

Welcome to this expert technical guide on the FAW Starter Motor (Part No. 3708010-53D-C00), the high-torque component responsible for “cranking” and starting the massive diesel engine in the FAW Jiefang CA4251P66K24T1A3E5 6×4 tractor.

The FAW Starter Motor is a critical assembly that must generate immense torque to overcome the high compression of a large-displacement diesel engine. A failure of this one component renders the entire truck inoperable. The FAW Starter Motor is not a single part, but a complex assembly of a high-current electric motor and a mechanical engagement system.

This in-depth guide is an essential resource for professional technicians, fleet maintenance managers, and parts specialists. We will deconstruct the entire FAW Starter Motor assembly and its critical mounting hardware, exploring the internal logic of the solenoid, the Bendix drive, and the high-tensile fasteners that secure it to the engine’s flywheel housing.

Core Component: The Starter Motor Assembly (3708010-53D-C00)

The main component is the ‘Starter Motor Assembly’ (3708010-53D-C00). This is the complete FAW Starter Motor unit, which is replaced as a single part. This is a heavy-duty, 24-volt, high-current DC (Direct Current) electric motor. Its function is to convert the battery’s electrical energy into the massive rotational force (torque) needed to spin the engine’s flywheel from a dead stop.

Unlike a car starter, this FAW Starter Motor is gear-driven. It mounts directly to the engine’s flywheel housing, where its pinion gear can engage the flywheel’s ring gear. The entire assembly is environmentally sealed to protect its sensitive internal components from water, road salt, and dirt, ensuring starting reliability in all weather conditions.

Internally, the FAW Starter Motor is comprised of two main sub-systems that work in perfect synchrony:

1. **The Main Motor:** The large, cylindrical body of the FAW Starter Motor. This is the “muscle” that contains the heavy copper field coils and the central rotating armature.
2. **The Solenoid:** The smaller cylinder mounted on top of the motor. This is the “brain” and “actuator” that controls the FAW Starter Motor.

Internal Logic 1: The High-Torque DC Motor & Gear Reduction

The “muscle” of the FAW Starter Motor is a powerful series-wound DC motor. This design is chosen specifically because its torque is inversely proportional to its speed; it produces the absolute maximum torque at zero RPM (stall), which is exactly what is needed to begin turning a cold, heavy diesel engine.

This power comes at a cost: a massive current draw. When the key is turned, this FAW Starter Motor can draw 800-1000 amps (or more) from the 24-volt battery system, a flow of energy that is immense. This current flows through the field coils and the armature via a set of “brushes” and a “commutator,” which are the primary wear items inside the FAW Starter Motor.

However, this DC motor spins very fast (e.g., 5,000-10,000 RPM) with relatively low torque. The engine’s flywheel needs to be turned very slowly (e.g., 100-200 RPM) but with enormous torque. To solve this mismatch, the FAW Starter Motor contains an **internal planetary gear reduction set**.

The high-speed shaft from the electric motor spins a small “sun” gear. This sun gear is meshed with several “planet” gears, which in turn mesh with a fixed “ring” gear (the outer wall of the gear case). This forces the “planet carrier” (which holds the planet gears) to rotate at a much slower speed, but with massively multiplied torque. The output shaft of this planetary carrier is what ultimately drives the Bendix gear. This “gear-reduction” design is what gives the FAW Starter Motor its incredible cranking power.

Internal Logic 2: The Solenoid and Bendix Drive

The solenoid, the smaller cylinder on top of the FAW Starter Motor, performs two critical functions at the same time.

**1. High-Current Relay:** The wire from the ignition key carries only a small (1-2 amp) signal. This signal energizes an electromagnet inside the solenoid. This magnet pulls a heavy copper-disc plunger across two massive copper contacts. This completes the main circuit, acting as a heavy-duty relay that allows the 800+ amps to flow from the battery directly to the FAW Starter Motor‘s main windings.

**2. Mechanical Actuator:** As the solenoid plunger is pulled in by the electromagnet, it is also connected to a “shift lever” or “fork.” This lever pivots and forcefully pushes the starter’s drive gear (the “Bendix” or “pinion” gear) forward, along a helical spline. This forward motion is what causes the starter’s pinion gear to physically engage and mesh with the teeth of the engine’s large flywheel.

This timing is perfect: the solenoid *first* meshes the gear, and *then* (at the end of its travel) closes the electrical contacts to power the motor. This ensures the motor only spins *after* the gears are fully engaged, preventing them from clashing and stripping.

The Bendix drive has one final, critical feature: an **overrunning clutch**. As soon as the engine fires and starts to run (at 600+ RPM), it will spin the flywheel much faster than the FAW Starter Motor is turning it. This clutch is a one-way mechanism. It allows the starter to turn the flywheel, but it “freewheels” in the other direction. This prevents the fast-spinning engine from back-driving the FAW Starter Motor, which would spin the starter’s armature at 50,000+ RPM and cause it to disintegrate from centrifugal force.

The Critical Mounting Hardware (4 Pieces)

The parts list for this FAW Starter Motor assembly focuses entirely on its mounting hardware. This is because the FAW Starter Motor is a “black box” component that is not typically serviced internally. However, its mounting is a critical, high-torque, high-vibration interface.

The list calls for three different ‘Hex flange bolts’:

• ‘Hex flange bolt, coarse rod’ (Q1841440) – 1 unit
• ‘Hex flange bolt, coarse rod’ (Q1841470) – 1 unit
• ‘Hex flange bolt, coarse rod’ (Q1841455) – 1 unit

The three different part numbers indicate that all three bolts have different lengths. This is common for a FAW Starter Motor, as it mounts to a complex, non-flat cast surface (the flywheel housing) and must clear other components. These “flange” bolts are essential, as the integrated washer head spreads the clamping load over a wide area, preventing the bolt from cracking the starter’s aluminum mounting flange.

The list also includes one ‘Hex head flange lock nut’ (Q032614). This implies that one of the starter’s mounting points is a **stud** (a bolt permanently threaded into the flywheel housing) rather than a bolt hole. The FAW Starter Motor slides onto this stud, and this “flange lock nut” is used to secure it. The “lock” feature (prevailing torque design) is critical to prevent this nut from backing off under the intense vibration of the diesel engine.

FAW Starter Motor Parts List

The following table provides the complete, detailed breakdown of all 5 components identified in the ‘Starter Motor’ diagram for the FAW CA4251P66K24T1A3E5 tractor. A secure mount is critical to the function of the FAW Starter Motor.

Technical Specifications and Assembly Context

The specifications for the FAW Starter Motor are defined by its function as a high-torque, gear-reduction electric motor. The entire FAW Starter Motor assembly is a safety-critical component for vehicle operation.