Cooling circuit

Various coolant circuits for 4-cylinder modular engines have been illustrated in the following overviews (technical revision 0).

High-temperature coolant circuit B46 and B48

The coolant circuit has been highlighted in colour to increase transparency. Blue represents a lower coolant temperature. Red represents a higher coolant temperature.

Index Explanation Index Explanation
1 Radiator 2 To the heat management module
3 Exhaust turbocharger 4 Engine oil-coolant heat exchanger
5 Heat exchanger for heating system 6 Position sensor of the heat management module
7 Heat management module 8 Mechanical coolant pump
9 Coolant temperature sensor 10 Expansion tank for the engine coolant circuit
11 Coolant level switch or coolant level sensor 12 Auxiliary coolant radiator (optional)
13 Electric fan 14 Thermostat for transmission oil-coolant heat exchanger (only automatic gearbox / optional)
15 Transmission oil-coolant heat exchanger (for automatic gearbox only) 16 Electric turbocharger coolant pump

Note!

It is possible that not all components have been fitted.

Low-temperature coolant circuit B46 and B48

The coolant circuit has been highlighted in colour to increase transparency. Blue represents a lower coolant temperature. Red represents a higher coolant temperature.

Index Explanation Index Explanation
1 Coolant radiator for low-temperature coolant circuit (only PHEV) 2 Coolant radiator for low-temperature coolant circuit
3 Low-temperature coolant circuit expansion tank 4 Coolant pump in low-temperature coolant circuit
5 Coolant pump 2 in low-temperature coolant circuit (only PHEV) 6 Engine block
7 Electrical Machine Electronics EME (only PHEV) 8 Convenience charging electronics KLE (only PHEV)
9 Charge air cooler 10 Coolant-cooled air conditioning condenser (coolant/refrigerant heat exchanger)

Note!

It is possible that not all components have been fitted.

Notes for Service department

General notes

Attention!

Do not open the sealing cap when the engine is hot. The reason for this is not only the risk of scalding.

Gas bubbles may develop in more elevated areas of the coolant circuit, such as at the cylinder head, as a result of the loss of pressure. Sufficient heat dissipation can no longer be guaranteed in these areas. Overheating would be the consequence.

Note!

The expansion tank features a visual filling level indicator. It is possible to read the filling level when the expansion tank is open. The filling level is between minimum and maximum if it has been correctly filled.

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