Transmission oil cooler circulation pump, component description - GF20.10-P-3201GZ

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MODEL 164.120 /122 /822, 251.020 /022 /122 with TRANSMISSION 722.9

Shows model 164.1

Location

The transmission oil cooler circulation is located the front right on the longitudinal member and is connected to the transmission oil cooler via an additional coolant circuit.

Fig 1: Identifying Check Valve And Transmission Oil Cooler Circulation Pump

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Task

The electrically operated transmission oil cooler circulation pump guarantees sufficient cooling of the transmission oil when the coolant thermostat is closed or open slightly. It is actuated by the CDI control unit (N3/9) according to the following parameters:

transmission oil temperature > 85°C
coolant temperature < 94°C

The electric engine and AC fan with integrated control (M4/7) is also actuated by the CDI control unit via pulse width modulation (PWM) according to the following transmission oil temperature values:

transmission oil temperature ≤ 95°C, PWM signal = 10 %
transmission oil temperature ≤ 98°C, PWM signal = 25 %
transmission oil temperature > 95°C and < 98°C, the PWM signal increases in a linear fashion by 5% at a transmission oil temperature increase of 1°C

So that the coolant flow quantity through the engine radiator is not reduced at high engine temperatures, whereby the cooling output would fall, a check valve is built into the additional coolant circuit.