Engine Cooling

The cooling circuit for engine cooling also supplies the bearing seats of the exhaust turbocharger with coolant. The electric auxiliary water pump with a power of 20 W supports the mechanical main coolant pump and ensures cooling of the exhaust turbocharger even after the engine has been stopped.

The electric auxiliary water pump is arranged in the engine cooling circuit so that when the combustion engine is at a standstill, coolant flows through the transmission fluid-to-coolant heat exchanger. This guarantees that the gearbox and its two electric machines are cooled when driving in pure electric mode.

As with the other models with an N63 engine, this pump also continues running after the combustion engine has been stopped in order to dissipate the residual heat away from the exhaust turbocharger (this can be for 15 to 20 minutes).