The Crucial Heart: FAW Oil Pump Assembly for the CA4251P66K24T1A3E5 Tractor

Welcome to this crucial technical guide on the FAW Oil Pump (Partie no. 1011010-81D), the component that serves as the heart of the engine’s lubrication system for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor.

Le FAW Oil Pump is a high-volume, positive-displacement pump responsible for one of the most critical functions in the engine: drawing oil from the oil pan sump and force-feeding it under high pressure to every vital component, from the crankshaft bearings to the piston cooling jets and the valvetrain.

This guide is an essential resource for professional engine technicians, rebuild specialists, and parts managers. We will deconstruct the entire FAW Oil Pump assembly into its smallest serviceable units, including its internal pressure relief valve, its outlet plumbing, and its critical mounting and sealing components. A failure of the FAW Oil Pump is not a minor issue; it is a catastrophic event that can destroy an engine in minutes.

Core Component: The Oil Pump Assembly (1011010-81D)

The main unit is the ‘Oil Pump Assembly’ (1011010-81D). This is the complete FAW Oil Pump unité, a precision-machined housing containing the pump’s core mechanism. In heavy-duty diesel engines, this is typically a gerotor-style pump or a spur-gear pump. It is a “positive displacement” conception, meaning it moves a fixed, constant volume of oil with every single engine revolution.

This pump is not driven by a belt; it is a high-torque, gear-driven component. It is typically mounted deep inside the engine on the main bearing bed plate and is driven directly by a gear on the crankshaft snout. This direct, “no-slip” drive is essential for reliability, as any failure in the FAW Oil Pump drive mechanism would result in zero oil pressure and immediate, catastrophic engine seizure.

The body of the FAW Oil Pump is typically cast from high-strength aluminum or iron, with extremely tight internal tolerances (measured in ten-thousandths of an inch) for its gear set. These tight clearances are what allow the pump to create the high suction needed to lift oil from the sump and the high pressure needed to force it through the engine’s narrow bearings and galleries. Any scoring or wear inside the FAW Oil Pump housing from contaminated oil will reduce these clearances, leading to a permanent loss of oil pressure.

The Pressure Limiting Valve (1011055-81D)

The single most important safety feature of the FAW Oil Pump is the ‘Oil pump pressure limiting valve assembly’ (1011055-81D). Because the FAW Oil Pump is a positive-displacement pump, its output pressure will continue to climb indefinitely as engine RPM increases. On a cold start-up in freezing weather, thick, high-viscosity oil can cause this pressure to spike to dangerous levels—high enough to rupture the oil filter canister or blow out seals.

This pressure limiting valve, also known as a pressure relief valve, is the engine’s built-in safeguard. It is a simple, spring-loaded piston (or ball-and-spring) assembly integrated directly into the FAW Oil Pump housing. The spring is precisely calibrated to a set pressure (Par exemple, 90 PSI).

During normal operation, the valve remains closed. If the oil pressure exceeds the spring’s setting, the pressure forces the piston open, which uncovers a “bypass” port. This port dumps the excess, high-pressure oil directly back into the *inlet* side of the FAW Oil Pump or back into the oil pan. This action “limits” ou “regulates” the maximum pressure in the entire lubrication system. A valve that is stuck open will cause permanently low oil pressure, while a valve that is stuck closed will cause the aforementioned pressure spikes. Its proper function is critical to the FAW Oil Pump.

Oil Outlet Plumbing and Connection

Once the oil is pressurized by the FAW Oil Pump and has passed the pressure relief valve, it must be sent to the rest of the engine. This is the job of the ‘Oil pump outlet pipe’ (1011041-81D). This is a rigid, pre-bent pipe that serves as the main artery, connecting the pump’s output port to the engine block’s main oil gallery.

This pipe connects to the ‘Oil pump outlet connector assembly’ (1011050-81D), which is the main “banjo” ou “bride” fitting that bolts onto the pump housing itself. This connection must be sealed against the full, high pressure of the FAW Oil Pump.

The parts list specifies one ‘Gasket ring’ (CQ72324) for this purpose. This is a critical crush washer, likely made of soft aluminum or copper. It is installed on the ‘Combination Bolt’ (CQ1461050) that secures the connector assembly to the FAW Oil Pump. When tightened, this gasket deforms to create a perfect, high-pressure seal. Re-using this washer is a major risk, as a leak at this point would not just be a drip; it would be a catastrophic, high-pressure spray that would drain the engine of oil in seconds.

Mounting, Alignment, and Sealing System

Le FAW Oil Pump must be mounted with absolute precision. Its internal drive gear must mesh perfectly with the crankshaft gear, and its intake/outlet ports must align exactly with the engine block’s galleries. This alignment is not achieved by the bolts; it is achieved by the two ‘Dowel Pins’ (1011012-D1). These are hardened steel pins that are pressed into the engine block. Le FAW Oil Pump housing has two corresponding holes. These dowels lock the pump in its one, exact location *before* the bolts are ever tightened.

The main body of the FAW Oil Pump is sealed to the engine block by the two ‘Seal Rings’ (1011042-81D). These are large, high-temperature O-rings. One ring seals the “admission” gallery (the low-pressure suction side coming from the oil sump/pickup tube). The other ring seals the “outlet” gallery (the high-pressure side going to the oil filter). A failure of the intake O-ring will cause the pump to suck air, leading to oil aeration and a loss of pressure. A failure of the outlet O-ring will cause high-pressure oil to dump directly back into the crankcase, also resulting in a total loss of oil pressure.

With the pump located by the dowels and sealed by the O-rings, it is secured by the ‘Combination Bolt’ (CQ1461070) unités. The list calls for four of these bolts, which secure the main housing of the FAW Oil Pump to the engine. Ces boulons, which feature captive spring-lock washers, are critical for preventing the FAW Oil Pump from vibrating loose over its service life.

FAW Oil Pump Parts List

The following table provides the complete, detailed breakdown of all components identified in the ‘Oil Pump’ diagram for the FAW CA4251P66K24T1A3E5 tractor. A professional service of the FAW Oil Pump requires the mandatory replacement of all gaskets and seal rings.

Technical Specifications and Assembly Context

The specifications for the FAW Oil Pump are defined by its function as the high-volume, gear-driven heart of the engine’s lubrication system. The reliability of the entire FAW Oil Pump is paramount.