FAW Fuel Oil Heater Logic Assembly: A Comprehensive Breakdown of 17 Key Components

Welcome to this comprehensive technical guide on the FAW Fuel Oil Heater Logic Assembly (Part No. 1312010-74T), a critical system for all-weather reliability on the FAW Jiefang CA4251P66K24T1A3E5 6×4 diesel semi-trailer tractor. This assembly is the engine’s primary defense against cold-weather fuel gelling.

The FAW Fuel Oil Heater Logic Assembly is a sophisticated heat-exchanger system. Its “logic” is to use hot engine coolant to heat the diesel fuel *before* it reaches the filters. This action prevents the paraffin wax in cold diesel from crystallizing (“gelling”), which would clog the fuel filters and starve the engine of fuel.

This guide is an essential resource for professional technicians and parts specialists. We will deconstruct the entire FAW Fuel Oil Heater Logic Assembly into its 17 serviceable components, including the main heater, the auxiliary electromagnetic pump, all coolant and fuel plumbing, and the mounting brackets.

Core Component: The Fuel Heater Assembly (1312010-74T)

The heart of the FAW Fuel Oil Heater Logic Assembly is the ‘Fuel Heater Assembly’ (1312010-74T). This is the main heat exchanger. It is a “liquid-to-liquid” cooler, operating in reverse: it uses hot liquid (coolant) to heat a cold liquid (fuel).

This unit is typically a “plate-style” or “shell-and-tube” exchanger. Hot engine coolant is forced through one set of internal passages, while cold diesel fuel from the tank is forced through a separate, alternating set of passages. The two fluids never touch, but the heat from the 80-90°C coolant is efficiently transferred through the thin metal plates to the sub-zero fuel.

This action raises the fuel temperature well above its “cloud point,” ensuring the paraffin wax stays in a liquid state. A failure of this FAW Fuel Oil Heater Logic Assembly core (e.g., an internal leak) is catastrophic. It can force high-pressure coolant into the fuel system, contaminating the injectors, or force diesel fuel into the cooling system, destroying all rubber hoses and seals. This makes the integrity of the FAW Fuel Oil Heater Logic Assembly paramount.

The Coolant “Piping” Circuit (1312035-74T)

The FAW Fuel Oil Heater Logic Assembly cannot create heat; it can only transfer it. The “piping” components are responsible for tapping into the engine’s main cooling system to acquire this heat. This circuit includes:

• ‘Fuel Heater Inlet Water Hose’ (1312038-74T)
• ‘Fuel Heater Outlet Water Hose’ (1312041-74T)
• ‘Fuel Heater Inlet/Outlet Steel Pipe Assembly’ (1312035-74T)
• ‘Return Water Hose’ (1312031-74T)

This system works by tapping hot coolant from a high-temperature point (like the thermostat housing) and routing it through the ‘Inlet Water Hose’ to the ‘Fuel Heater Assembly’. The ‘Steel Pipe Assembly’ provides a rigid, protected path along the chassis or engine. After the coolant has transferred its heat, the now-cooler fluid is sent back to the low-pressure side of the water pump via the ‘Outlet Water Hose’ and ‘Return Water Hose’. This continuous circulation is the “logic” of the FAW Fuel Oil Heater Logic Assembly.

These hoses are secured with ‘Worm Drive Hose Clamps’ (CQ67630B). A leak in any of these components will not only disable the FAW Fuel Oil Heater Logic Assembly, but will also cause the engine to lose coolant and overheat.

The “Logic”: Electromagnetic Pump Assembly (1312020-74T)

The most advanced “logic” component of the FAW Fuel Oil Heater Logic Assembly is the ‘Electromagnetic Pump Assembly – with wire harness’ (1312020-74T). This is a critical auxiliary pump.

The engine’s main water pump is mechanical and only circulates coolant when the engine is running. This is a problem on a sub-zero “cold start.” The FAW Fuel Oil Heater Logic Assembly needs to heat the fuel *before* the engine starts.

This ‘Electromagnetic Pump’ is the solution. When the driver turns the key to the “on” position, the ECU activates this 24V electric pump. This pump immediately begins to circulate hot coolant from the (still warm from a block heater, or a Webasto-style heater) engine block, through the ‘Fuel Heater Assembly’, and back to the engine. This “pre-heat” cycle runs for 30-60 seconds *before* the starter is engaged, ensuring the fuel in the lines is already warm and de-gelled.

This pump, with its integrated ‘wire harness’, is the “brain” that makes the FAW Fuel Oil Heater Logic Assembly an *active* system, not a passive one. It is likely routed via the ‘Three-way Joint Assembly’ (1312070-29T), which allows coolant to be sourced from either this pump or the main water pump, depending on whether the engine is on or off. The FAW Fuel Oil Heater Logic Assembly‘s effectiveness depends entirely on this pump.

Brackets, Seals, and Fasteners

The entire FAW Fuel Oil Heater Logic Assembly is a heavy, fluid-filled unit that must be protected from vibration. The ‘Fuel Heater Bracket Assembly’ (1312050-74T) is the main structural support. It bolts to the chassis, and the ‘Fuel Heater Assembly’ then bolts to this bracket.

Additional ‘Bracket’ (3406111-20V) units are used to secure the rigid ‘Steel Pipe Assembly’ (1312035-74T) and the ‘Electromagnetic Pump’, preventing them from fatiguing and cracking.

The system is sealed with the ‘Gasket ring’ (CQ72327) and ‘Joint’ (1312036-74T), which are single-use crush washers for the fluid connections. The entire FAW Fuel Oil Heater Logic Assembly is fastened with a variety of high-grade hardware: ‘Hex flange bolts’ (Q1841435, Q1840820) and ‘Hex flange nuts’ (CQ39614, CQ39608). The ‘Plastic Zip Ties’ (T67420376) are used to secure the flexible hoses and wiring harness away from any hot or moving parts, completing the installation of the FAW Fuel Oil Heater Logic Assembly.

FAW Fuel Oil Heater Logic Assembly Parts List

The following table provides the complete, detailed breakdown of all 17 components identified in the ‘Fuel Oil Heater Logic Assembly’ diagram for the FAW CA4251P66K24T1A3E5 tractor. This FAW Fuel Oil Heater Logic Assembly is essential for cold-weather starting.

Technical Specifications and Assembly Context

The specifications for the FAW Fuel Oil Heater Logic Assembly are defined by its function as an active, coolant-based heat exchanger. This entire FAW Fuel Oil Heater Logic Assembly is a key system for cold-weather operation.