BMW 17217536929 Transmission Oil Cooler Heat Exchanger

Remove the splash shield from under the engine and drain the cooling system. It is important to cover the alternator when working on oil, coolant, or fuel circuits to protect it from damage. Remove the coolant hoses and the screw from the underside of the ATF cooler. Use BMW special tool 17 0 030 to unlock the transmission fluid from the hydraulic lines and remove the ATF cooler. Installation is the reverse of removal, and it is essential to check the automatic transmission fluid level, refill and bleed the cooling system, and check the cooling system for leaks.

ATF lines run from the transmission to the back part of the radiator proceeding to the ATF cooler. Cold start of an engine warms the engine coolant more than warms the transmission fluid by circulating the heat from the coolant, and improves the efficiency of the drag in the transmission to entail better fuel economy. When the ATF is at the normal running temperature it tends to be slightly hotter than the engine coolant and serves as a cooling apparatus for the ATF heat exchanger. That is why when dealing with the cooling system, it is always wrong to pour cold water into the coolant when the engine is hot or has overheated; if at all, one must use hot water to mix with the coolant while the engine is running and the water pump is also functioning. To try and avoid further formation of silicate gel, deposition and the potential reduction of cooling capacity, it is better to use BMW coolant or its equivalent low silicate antifreeze. When oil has been admitted into the cooling system, the radiator together with the expansion tank and heating circuit require washing with a cleaning agent and it is advisable that the radiator and expansion tank be detached for thorough washing. Also, if there is a job on the cooling system, the alternator must be blanked off to prevent drips on hot components and before disconnecting the battery, one should know some important precautions about battery disconnection.