GF27.55-P-2000AHW Transmission Oil Cooling, Function

GF27.55-P-2000AHW Transmission Oil Cooling, Function
TRANSMISSION 722.9 (except 722.930) in MODEL 204.0 as of model year 2009 /YoM 08
TRANSMISSION 722.9 (except 722.930) in MODEL 204.2 as of model year 2009 /YoM 08
TRANSMISSION 722.9 (except 722.930) in MODEL 204.3
TRANSMISSION 722.9 in MODEL 204.9

Function requirements for transmission cooling, general
^ Circuit 87 (connected circuit 15) ON
^ Circuit 61 (engine running)

Transmission cooling, general
To reach the operating temperature of the transmission quicker, the transmission oil is heated by the engine's cooling circuit. Transmission oil cooling lowers the temperature of the transmission oil and thus prevents overheating damage in the transmission.

For engine 271 and engine 651 a transmission oil heat exchanger is installed as of YoM 11. With engine 274, implementation begins as of YoM 12. This means that a transmission cooler need not be used.

Function sequence for transmission oil cooling
The transmission oil is drawn out of the transmission oil pan by a mechanical pump in the transmission and is pumped via the feed to the transmission oil heat exchanger (which is integrated in the engine radiator). The transmission oil then flows through the return line back to the transmission.
On vehicles with an additional transmission oil cooler the transmission oil flows from the transmission oil heat exchanger to the transmission oil thermostat. At a transmission oil temperature <90 °C, the transmission oil thermostat directs the transmission oil back to the transmission via the return.
The transmission oil thermostat opens at a transmission oil temperature >90 °C and the transmission oil flows through the auxiliary transmission oil cooler before it flows through the return back to the transmission.