The Complete Guide: FAW Oil Pan for the CA4251P66K24T1A3E5 Tractor

Welcome to the complete technical guide for the FAW Oil Pan (Part No. 1009010-99C), the critical lubrication reservoir for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This assembly is the foundation of the engine’s entire oiling system.

The FAW Oil Pan is not just a simple container; it is an engineered system designed to safely store, cool, and manage the engine’s oil supply. It ensures that the oil pump pickup is constantly submerged, even under the extreme conditions of heavy hauling, steep grades, and sharp turns.

This in-depth guide is a vital resource for professional technicians, fleet managers, and parts specialists. We will deconstruct the entire FAW Oil Pan assembly into its smallest serviceable units, including the main pan, its complex internal baffling, the gasket, drain plug, and all associated fasteners.

Core Component: The Oil Pan Assembly (1009010-99C)

The largest and most significant component is the ‘Oil Pan Assembly’ (1009010-99C). This is the main reservoir that holds the engine’s entire supply of lubricating oil (often 30+ liters in an engine of this size). It is typically manufactured from stamped, deep-draw steel or cast aluminum. A stamped steel FAW Oil Pan offers excellent durability against impacts, while a cast aluminum pan (which this likely is, given the complex internal structure) offers superior rigidity and heat dissipation.

The design of the FAW Oil Pan is critical. The “sump” is the lowest, deepest part of the pan, designed to collect the oil and provide a deep, stable reservoir for the oil pump pickup tube. The entire pan also acts as a passive oil cooler; the hot oil returning from the engine spreads across the pan’s large surface area, and the airflow underneath the truck helps dissipate heat, maintaining the oil’s viscosity and lifespan.

A damaged FAW Oil Pan, whether from a road debris impact or a cracked weld, is a critical failure. Even a small leak can quickly drain the engine of oil, leading to catastrophic failure of the crankshaft bearings and turbocharger. The structural integrity of the FAW Oil Pan is fundamental to engine health.

The Critical Seal: Oil Pan Gasket (1009031-81D)

The ‘Oil Pan Gasket’ (1009031-81D) is the single component responsible for creating a leak-proof seal between the FAW Oil Pan and the engine block’s “bed plate” or “skirt.” In modern diesel engineering, this is no longer a simple cork or paper gasket.

This part is a high-tech “profile” gasket. It is typically constructed as a rigid steel carrier plate, which has been stamped into the exact shape of the pan’s rail. A high-grade, oil-resistant elastomer (like silicone or FKM) is then precision-molded onto this carrier, with raised “beads” that trace the bolt holes and the perimeter.

This design is vastly superior to older gasket types. The steel carrier prevents the gasket from “squeezing out” or “extruding” when the 34 pan bolts are tightened. The molded elastomer beads provide a concentrated, high-pressure seal with minimal clamping force, ensuring a durable, vibration-resistant, and leak-free joint. This gasket is a single-use item; once it has been compressed, it must be replaced to guarantee a proper seal when servicing the FAW Oil Pan.

Internal Baffling: Controlling Oil Surge

The most complex and arguably most important components *within* the FAW Oil Pan are its baffles. A 6×4 tractor is subjected to immense G-forces: hard acceleration, heavy braking, and high-G turns. Under these conditions, the 30+ liters of oil would “slosh” or “surge” violently, like water in a bucket. If this surge momentarily uncovers the oil pump pickup tube, it will suck air. This “oil starvation,” even for a fraction of a second, is fatal to an engine, as it will instantly destroy the bearings.

This FAW Oil Pan features a complex, multi-part baffling system to prevent this. The parts list calls for four ‘Turning Baffles’ (1009026-81D), two ‘Front Intermediate Baffles’ (1009023-81D), and two ‘Rear Intermediate Baffles’ (1009024-81D). This total of eight internal plates creates a “trap” or “maze” around the oil sump.

The ‘Turning Baffles’ are likely the “walls” that form a box around the sump. They feature small, one-way “trap doors” that allow oil to flow *in* to the sump easily, but prevent it from sloshing *out* during a turn. The ‘Intermediate Baffles’ are plates that run along the length of the FAW Oil Pan, controlling the “fore-and-aft” slosh that occurs during braking and acceleration.

These baffles also serve a second function as a “windage tray.” The crankshaft, spinning at thousands of RPM, acts like a giant whisk, creating an oil “cloud” or “rope” in the crankcase. This “windage” robs the engine of power (parasitic loss) and can overwhelm the piston’s oil control rings. These baffles are positioned to strip this oil from the air, allowing it to drain calmly back into the sump. The design of this baffling system is a key engineering feature of the FAW Oil Pan.

Service and Monitoring Components

The parts list includes the two primary points of service for the FAW Oil Pan. The ‘Oil dipstick assembly’ (1009070-99C) is the only component used for monitoring the oil level. This assembly includes the dipstick itself (a long, flexible metal blade), the tube it sits in, and the O-ring seal on its handle to prevent crankcase pressure from escaping.

The second, and most frequently used, service point is the ‘Oil pan drain plug’ (1009022-29D). This is a heavy-duty, threaded bolt located at the absolute lowest point of the FAW Oil Pan. It is designed to allow for the complete drainage of all used engine oil during a service.

Critically, this plug is sealed by its own ‘Gasket ring’ (CQ72320). This is a “crush washer,” typically made of soft aluminum, copper, or a composite. When the drain plug is tightened, this soft ring “crushes” to form a perfect, liquid-tight seal against the pan. This gasket is a single-use item. Re-using an old, work-hardened gasket ring is the #1 cause of a leaking drain plug. A professional service of the FAW Oil Pan always includes a new gasket ring.

The Fastener System: A Study in Clamping Force

The integrity of the FAW Oil Pan seal is entirely dependent on its fastener system. The parts list calls for two different bolts: eight units of ‘Hex flange bolt, coarse rod’ (Q1841225) and 26 units of ‘Hex flange bolt, coarse rod’ (Q1840820).

This massive quantity of **34 bolts** is necessary to provide perfectly uniform clamping pressure along the entire perimeter of the gasket. The long, thin rail of a stamped steel or cast aluminum FAW Oil Pan is flexible; if fewer bolts were used, the pan would warp between the bolts, creating a “scalloped” leak path. The two different part numbers indicate different bolt lengths or diameters, used for specific locations on the pan (e.g., where it passes over the main bearing cap seals).

These “flange” bolts are critical. The integrated washer head spreads the clamping force over a wide area, preventing the bolt head from cracking the pan’s flange or crushing the gasket unevenly. These bolts must be tightened to a low, specific torque (e.g., 18-25 N·m) in a precise, multi-stage, crisscross pattern to ensure the FAW Oil Pan seats correctly.

FAW Oil Pan Parts List

The following table provides the complete, detailed breakdown of all components identified in the ‘Oil Pan’ diagram for the FAW CA4251P66K24T1A3E5 tractor. This list is essential for any service of the FAW Oil Pan.

Technical Specifications and Assembly Context

The specifications for the FAW Oil Pan are defined by its function as a high-capacity, structural oil reservoir with an advanced internal baffling system.