Maintaining Engine Health: A Critical Guide to the FAW Engine Oil Cooler

Welcome to this critical technical guide on the FAW Engine Oil Cooler (Part No. 1013010-81D), a vital component for the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This system is non-negotiable for engine longevity under heavy-duty conditions.

The function of the FAW Engine Oil Cooler is to regulate the temperature of the engine’s lubricating oil. It uses the engine’s own coolant (antifreeze) as a medium to absorb and carry away excess heat from the oil, ensuring the oil’s viscosity and lubricating properties remain stable under high loads.

This guide is an essential resource for professional engine technicians, fleet managers, and parts specialists. We will deconstruct the entire FAW Engine Oil Cooler assembly, including its complex heat exchanger core, its integrated pressure-regulating bypass valve, and all associated gaskets, seals, and fasteners.

Core Component: The Oil Cooler Assembly (1013010-81D)

The heart of the system is the ‘Engine oil cooler assembly’ (1013010-81D). This is the main heat exchanger unit of the FAW Engine Oil Cooler. This component is a “stacked-plate” type cooler, which is far superior to older “fin-and-tube” designs. It consists of numerous thin, precisely stamped metal plates.

These plates are brazed together in a stack, creating two separate, alternating sets of passages. Hot engine oil is forced through one set of passages, while cool engine coolant is forced through the alternating set in the opposite direction (a “counter-flow” design). This creates the maximum possible thermal differential, allowing heat to transfer efficiently from the hot oil, through the thin plate, and into the cooler coolant.

The integrity of this core is paramount. Over time, or due to a manufacturing defect, one of the internal brazed joints can fail, creating a microscopic crack between the oil and coolant passages. This is a catastrophic failure, as it will allow high-pressure engine oil to be forced into the low-pressure cooling system (blowing out hoses) or, worse, allow corrosive coolant to enter the oil, destroying the engine’s bearings. A failed core in the FAW Engine Oil Cooler necessitates the replacement of the entire assembly.

The Critical Mounting Gasket (1013012-81D)

The ‘Engine oil cooler gasket’ (1013012-81D) is the single main seal that connects the entire FAW Engine Oil Cooler assembly to the engine block. This is a large, complex “profile” gasket, not a simple flat piece of paper.

This gasket is typically made of a steel carrier plate with precision-molded elastomer (rubber) seals. It must seal four different passages simultaneously:

1. **Dirty Oil In:** The passage from the oil pump *to* the FAW Engine Oil Cooler.
2. **Clean Oil Out:** The passage from the cooler *to* the engine’s main oil galleries.
3. **Coolant In:** The passage from the engine block *to* the FAW Engine Oil Cooler.
4. **Coolant Out:** The passage from the cooler *back* to the water pump.

A failure of this one gasket is just as catastrophic as an internal core failure. If the seal between the “oil in” and “coolant in” passages breaks down, the oil and coolant will mix, resulting in the “milkshake” of death in the oil pan and radiator. This gasket is a single-use item. Any time the FAW Engine Oil Cooler is removed for service, this gasket *must* be replaced.

The Pressure Regulating Valve System (1013060-81D)

The most complex part of the FAW Engine Oil Cooler is its integrated oil filter base and bypass valve system. The parts list shows a ‘Pressure regulating valve assembly’ (1013060-81D). This valve is a critical safety device. On a cold start-up, the engine’s oil is thick and has a very high viscosity. Forcing this cold, thick oil through the stacked-plate cooler’s tiny passages would create immense back-pressure, potentially starving the engine of oil for several critical seconds.

This pressure regulating valve acts as a **thermostatic bypass**. It is a spring-loaded valve (spring part 1013053A53D) that senses oil pressure (or sometimes temperature). When the oil is cold and thick, the high pressure forces this valve *open*. This allows the oil to *bypass* the cooler core entirely, flowing directly from the pump to the engine’s galleries. This ensures the engine receives oil *immediately* upon startup.

As the engine warms up, the oil thins out, its pressure drops, and the spring (1013053A53D) forces the valve *closed*. This closure then forces 100% of the hot oil to circulate through the FAW Engine Oil Cooler core, as it is now needed for cooling. A failure of this valve is a major problem: if it sticks open, the oil will never be cooled, and the engine will overheat. If it sticks closed, the engine will be starved of oil on every cold start.

The FAW Engine Oil Cooler housing also contains the ‘Full-flow filter connecting bolt’ (1013041-53D), which is the large, threaded “nipple” that the spin-on oil filter attaches to. The entire assembly (cooler and filter) is housed by a complex system of covers and valves: ‘Cover-oil cooler bypass valve’ (1013031-53D), ‘Seat-oil cooler bypass valve’ (1013032-53D), ‘Valve-oil cooler bypass valve’ (1013033-53D), and the associated ‘Seat’ (1013051-53D) and ‘Bypass valve’ (1013052-53D). This entire sub-assembly is what “logically” routes the oil through the FAW Engine Oil Cooler system.

Seals, Gaskets, and Fasteners

A complex housing like the FAW Engine Oil Cooler, which manages multiple fluids, is sealed by a large number of components. The parts list details numerous ‘O-rings’ (1013034-53D, 1013037-53D, 083452_1.46_2x3.55) and ‘Gaskets’ (CQ72322, Q40106, Q40306). These are used to seal the various valve covers, plugs, and connecting bolts.

It also includes several ‘Copper Gaskets’ (Q/WC3403_20x28, Q/WC3403_27x35, Q/WC3403_30x40). These are high-temperature, high-pressure “crush washers.” They are used to seal banjo bolts or large threaded plugs, such as the ‘Inner hex socket screw plug M27x1.5’ (Q/WC3410_M27x1.5). These plugs cap off the galleries created during the manufacturing and machining of the FAW Engine Oil Cooler housing.

The entire FAW Engine Oil Cooler assembly is secured to the engine block by a specific set of fasteners. This includes numerous ‘Hex flange bolts’ of various R-types (Q1820810T, Q1820845, Q1820855, Q1821070) and ‘Hex cap bolts’ (CQ1500625). The high quantity and variety of these bolts are necessary to provide precise, even clamping pressure on the main gasket (1013012-81D) to prevent leaks. The proper torque sequence and specification for these bolts are critical during reassembly of the FAW Engine Oil Cooler.

FAW Engine Oil Cooler Parts List

The following table provides the complete, detailed breakdown of all components identified in the ‘Engine Oil Cooler’ diagram for the FAW CA4251P66K24T1A3E5 tractor. A professional service of the FAW Engine Oil Cooler requires replacing all O-rings and gaskets.

Technical Specifications and Assembly Context

The specifications for the FAW Engine Oil Cooler are defined by its complex function as a multi-fluid heat exchanger and integrated oil bypass system. The entire FAW Engine Oil Cooler assembly is a zero-leak tolerance component.