BMW 3 Owners & Service Manuals

BMW 3: Split cooling

Split cooling is a new development for the B46TU engine. This cooling concept is a modified version of which is already used in the N63TU2.

The Split Cooling function uses the electrical Split Cooling Valve (SCV), to enable on-demand decoupling of the crankcase from the coolant flow both in the warm-up phase and in partial load operation. In this situation, the coolant is exclusively routed through the cylinder head. The engine reaches its operating temperature more quickly in the warm-up phase, and can be operated with reduced emissions in partial load operation.

Split cooling
Coolant circuit

  1. High cooling requirement, Split Cooling cylinder head
  2. Low cooling requirement, Split Cooling crankcase
  1. Cylinder head
  2. Crankcase
  3. Heat management module
  4. Split Cooling Valve (SCV)
  5. Coolant pump

Split cooling
Cooling system overview

  1. Radiator
  2. Coolant temperature sensor radiator outlet
  3. Additional coolant radiator
  4. Electric fan
  5. Split Cooling Valve (SCV)
  6. Coolant pump
  7. Bypass valve
  8. Engine block (crankcase)
  9. Coolant temperature sensor engine outlet
  10. Cylinder head
  11. Exhaust turbocharger
  12. Heater core
  13. Expansion tank
  14. Component temperature sensor
  15. Engine oil/coolant heat exchanger
  16. Transmission oil/coolant heat exchanger
  17. Heat management module
  18. Additional coolant radiator

In Split Cooling, the cooling requirements for the crankcase and the cylinder head are managed by the electrical Split Cooling Valve (SCV). The fact that the engine reaches operating temperature more quickly again translates to substantial consumption and emission reductions.

To guarantee optimal heat distribution during the cylinder head and crankcase warm-up, the coolant supply for the cylinder head and crankcase is controlled individually. Controlled by the Digital Motor Electronics (DME), the coolant is distributed by the electrical Split Cooling Valve (SCV) on the heat management module in the warm-up phase such that substantially more coolant is available to the cylinder head than to the crankcase. Depending on the engine's operating condition, the Digital Motor Electronics (DME) controls the distribution of the coolant quantity to the cylinder head and crankcase as required.

A bleeding procedure must be carried out in accordance with the repair instructions and is required following a part exchange in the cooling system or refilling of the cooling system.

A video demonstrating the bleeding procedure can be found in the B46TU Engine on-line course (OL1837).

Filling without a vacuum filler device (watering can filling) is not approved There is a risk of engine damage in case of failure to comply The filling procedure must be observed Operation of the vehicle is not permitted without completing the entire filling procedure sequence.

There is a risk of functional limitations or overheating.


     Heat management module

    The heat management module replaces the characteristic map thermostat. Heat management module Electrical Split Cooling Valve (SCV) Coolant output towards the coolant pump Electrical actuator Rot

     Operating strategy

    The following graphic shows the positions of the rotary valve as the coolant temperature increases: Switching diagram heat management module 0% - Rotary valve closed 100% - Rotary valve open Cold

     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



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     Automatic climate control - switching on/off

    Switching on Press any button except for the following: Switching off. Rear window defroster. Lower air flow button side. Seat heating. Switching off Complete system: Press the button until the control panel switches off. Temperature Concept The automatic climate control achieves the set temp

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