The fuel oil heater is a heat exchanger that uses hot engine coolant to warm incoming diesel fuel before it reaches the injectors. In sub-freezing temperatures, diesel fuel can gel or precipitate paraffin wax, which quickly clogs primary fuel filters and starves the engine. By maintaining the fuel at a safe temperature, this system ensures reliable traction power during harsh winter operations.
Shop notes say the FOH is leaking coolant into the fuel lines, so we need to bypass it until the heat exchanger is swapped.
Mechanical forces typically valve in the fuel oil heater during the autumn winterization process and bypass it in the spring to prevent overheating the fuel.
Related terms
Locomotive
A self-propelled rail vehicle designed to provide the motive power for a train.
Diesel locomotive
A motive power unit that uses a diesel engine to generate electricity for electric traction motors.
Engine room
The enclosed compartment inside a locomotive carbody that houses the prime mover and main generator.