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BMW M57 Cooling System

Cooling-circuit reference for the BMW M57 diesel — thermostat, water pump, radiator and coolant routing.

System overview: Coolant circuit provides long-term protection against frost and corrosion. The M57 cooling design is identical to that of the M51. All water-carrying hose connection points are plug-in connections (as on M47). Components: water pump, thermostat, radiator, fan/shroud, auxiliary heater, independent park heating (option).
Part circuits: Engine, Heating, Expansion tank (all circuits). Engine oil cooler = M57 only. Alternator + EGR cooler = Not used on the M57.
Water pump: Located on the end face of the crankcase. Thermostat integrated in water pump housing. Leakage directed through drainage tubes into the pulley.
Thermostat — opening temperature: 88 °C — Integrated in water pump housing; no characteristic-map cooling.
Radiator / cooling assembly: M47 cooling concept adapted and further developed. Gear oil cooler integrated in the cooling assembly. Intercooler capacity adapted to increased volume; integrated in centre of cooling assembly. M57 E38/E39 stack (Fig. 48): power steering cooling loop, gear oil cooler, assembly frame, A/C-condenser, intercooler.
Coolant change interval: Every 4 years
Coolant fill capacity — M57 E38/E39: approx. 9.2 litre
Fan: The M57 uses a 7-blade plastic fan driven by a viscous clutch (better cooling capacity than an electric fan). An additional electric fan, activated by the DDE, is arranged in front of the radiator assembly. M57 cooling assembly (Fig. 49): radiator, fan shroud, viscous fan, intercooler.
Fan shroud — vehicle-specific (M57): Vehicle-specific fan shrouds with different apertures fitted to E39 and E38 due to a fan displacement of approx. 20 mm. The fan will be damaged if the shrouds are interchanged. Identification code cast into top inside of shroud: E39 M57 = 'A'; E38 M57 = 'B'.
M57-specific cooling features: AUC sensor located below the centre of the fan shroud. Expansion tank mounted behind the headlights.
Exhaust hood / shutter: No radiator shutters are currently installed on the M57.
Auxiliary heater / park heating: Auxiliary heater connected to the heating circuit fitted as standard in M57 E38/E39 (as on M47), installed instead of independent park heating. If the independent park heating option is installed, the separate auxiliary heater is dropped and the park heating assumes its function. Coolant-circuit schematics: M57 with ZHG — Fig. 43; M57 with SHG — Fig. 44 (labels: Radiator, ÖWWT oil-to-water heat exchanger, AGB expansion tank, heating heat exchanger).