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.

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

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.

There is a risk of functional limitations or overheating.

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