Hyundai Tucson Transmission Oil Cooler and Valve Kit 25620-D3000

This kit replaces the transmission oil cooler (also called the ATF warmer), part 25620-D3000, and its coolant control valve, part 25630-D3000. Both come in the box.

Fitment: 2016-2021 Hyundai Tucson with the 2.0L engine, 2018-2021 Tucson with the 2.4L, 2017-2018 Kia Sorento with the 2.4L, and 2017-2020 Sorento with the 3.3L. Match your old part numbers before you order.

How it works: this is a coolant-to-ATF heat exchanger, not a finned air cooler. Engine coolant runs through one side and transmission fluid through the other. When the engine is cold, the valve sends coolant through the exchanger so the ATF warms up faster. When everything is hot, the cooler pulls heat out of the fluid. If a cooler plate cracks inside, coolant and ATF can mix. Look for milky pink ATF or a coolant level that keeps dropping with no outside leak. That condition ruins clutch material and needs attention right away. External seepage at the cooler or the valve housing is the other common reason these get replaced.

On install: drain enough coolant to get below the cooler, disconnect the coolant hoses and ATF lines, and unbolt the cooler and valve. Use new sealing rings, torque the fasteners evenly, then refill and bleed the cooling system. Check and correct the ATF level following the procedure for your transmission. If coolant got into the ATF, flushing the fluid will not be enough, so inspect the transmission before you put the vehicle back in service.