BMW S58 Owner's Handbook Manual page 92

S58￿Engine
11.￿Cooling￿System
Index

9

10
The￿electric￿coolant￿pump￿for￿the￿turbochargers￿is￿a￿20 W￿pump￿which￿communicates￿with￿the
DME￿via￿a￿LIN￿bus.￿The￿conventional￿coolant￿pump￿is￿driven￿via￿the￿drive￿belt￿and￿cannot￿be￿used
for￿cooling￿the￿exhaust￿turbocharger￿after￿the￿engine￿has￿shut￿down.￿This￿is￿why￿there￿is￿an￿electric
coolant￿pump￿for￿this￿separate￿cooling￿circuit.￿But￿also￿during￿engine￿operation￿the￿electric￿coolant
pump￿is￿switched￿on￿taking￿into￿account￿the￿following￿factors:
• Coolant￿temperature￿at￿the￿engine￿outlet
• Engine￿oil￿temperature
• Injected￿fuel￿quantity
Using￿these￿values￿the￿heat￿input￿into￿the￿engine￿is￿calculated.￿The￿run-on￿period￿of￿the￿electric
coolant￿pump￿can￿last￿up￿to￿30 min.￿To￿improve￿the￿cooling￿effect,￿the￿electric￿fan￿also￿cuts￿in￿and￿may
run￿on￿for￿up￿to￿11 min.
11.2.2.￿Charge￿air￿cooling
In￿the￿S58￿engine,￿like￿in￿the￿B58TU￿engine,￿so-called￿"indirect"￿charge￿air￿cooling￿is￿used.￿During
the￿indirect￿charge￿air￿cooling￿the￿charge￿air￿is￿cooled￿via￿a￿low-temperature￿cooling￿circuit.￿The￿low-
temperature￿coolant￿circuit￿is￿then￿cooled￿again￿by￿the￿atmospheric￿airflow￿induced￿by￿vehicle￿motion
acting￿on￿two￿water-to-air￿heat￿exchangers.
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Explanation
Electric￿coolant￿pump￿for￿exhaust￿turbocharger
Exhaust￿turbocharger