BMW 3 Owners & Service Manuals

BMW 3: Operating strategy

The following graphic shows the positions of the rotary valve as the coolant temperature increases:

Operating strategy
Switching diagram heat management module

0% - Rotary valve closed
100% - Rotary valve open

  1. Cold start
  2. Warm-up phase
  3. Operating temperature
  4. Transition from normal operation to maximum cooling requirement
  5. Maximum cooling requirement

X - Rotational angle in angular degrees

  1. Heater circuit
  2. Main coolant circuit
  3. Minor coolant circuit

The openings on the rotary valve vary the cross-sections of the different coolant ducts as a function of the rotational angle of the rotary valve. The following graphics schematically represent the various engine operation phases, from cold start to maximum cooling requirement.

Cold-start phase

Point A in the heat management module circuit diagram designates the cold start with an engine that has completely cooled down.

Operating strategy
Cold-start phase

In the cold-start phase, the coolant circulates exclusively via a bypass in the coolant pump. The rotary valve in the heat management module closes the coolant lines so that the excess pressure that builds up opens the pressure relief valve in the coolant pump (opening pressure 2.2 bar) and the coolant is recirculated in the coolant pump.

Because the coolant circuits through the exhaust turbocharger and the ventilation line of the cylinder head cannot be closed, a low volumetric flow is returned to the coolant pump here.

Warm-up phase

Area A in the circuit diagram for the heat management module shows the opening angle of the rotary valve in the warm-up phase.

Operating strategy
Warm-up phase

In the warm-up phase, the heat management module additionally opens the connection to the heating in addition to opening the bypass line. The coolant flows through the cylinder head, the exhaust turbocharger and the engine oil/coolant heat exchanger. The electrical Split Cooling Valve is closed; no coolant flow through the engine block (Split Cooling).


     Operating temperature

    The positions of the rotary valve at engine operating temperature are shown by area C of the heat management module circuit diagram. Operating temperature The graphic shows control with the engine a

     Coolant pump

    The layout and function of the coolant pump have been revised and adapted to match the cooling concept of the B46TU/B48TU engines. Coolant pump Pressure relief valve closed (pressure <

     Exhaust System

    Exhaust turbocharger Exhaust turbocharger The exhaust turbocharger can be replaced individually and is exclusively made of steel. The boost charge pressure is still controlled by an electrical waste


     Functional requirements

    Compatible device, with Bluetooth interface. The vehicle key is in the vehicle. The device is ready for operation. Bluetooth is switched on in the vehicle and on the device. The pairing readiness is displayed on the Control Display. Bluetooth presettings, such as visibility, may be requir

     Stored trips

    General information Up to 30 trips can be stored in the trip list. If necessary, delete existing trips to be able to store new trips. Storing The destination guidance for the tip must be active. 1. Press the button on the Controller. 2. "Destination options". 3. "Save trip". 4. Enter the name.

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