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labudski
05-11-2015, 12:09 AM
Was just under-doing my spring inspection. I see some lines that appear to be coming out of the diesel fuel tank...theres 2 of them - coiling up.... never seen anything like this? What is it?

bc339
05-11-2015, 01:35 AM
They are heat exchangers for the return fuel. After the fuel passes through the high pressure pump, it is pretty warm. The fuel that is not used by the engine is returned to the fuel tank. Before it goes into the tank, it passes through the coils to dissipate the heat.

Bruce

labudski
05-11-2015, 01:51 AM
Thanks! is that true with all diesels? all fuel injected cars too?

bc339
05-11-2015, 02:25 AM
Not all diesels will have a cooling or heat exchanger system. Gas fuel injection systems operate at much lower pressures - low hundreds of PSI. Diesel systems can operate in the thousands of PSI, depending on the fuel delivery design. The higher the pressure, the more heat is created, hence the reason for cooling the return fuel.

Bruce