8L90 Transmission Thermal Bypass Valve with 3/8 Inch Line

This is a replacement for the GM 8L90 eight-speed transmission fluid thermal bypass valve, GM part 13561467, for trucks with 3/8 inch cooler lines. Listed fitment is 2015-2018 Chevrolet Silverado 1500 and GMC Sierra 1500, 2015-2017 GMC Yukon and Cadillac Escalade, 2016-2017 Yukon XL, and 2018-2025 Chevrolet Express 2500 and GMC Savana 2500. It does not fit the 6L80 or any truck with 1/2 inch cooler lines.

The factory valve holds fluid out of the cooler until the transmission warms up. When the thermal element sticks or the passages restrict flow, the fluid skips the cooler and transmission temperature climbs while towing, hauling or sitting in traffic. Heat is what breaks down ATF and cooks clutches, so a truck that shows high trans temps with a clean cooler is a good candidate. This valve uses a machined aluminum body with a full-flow path so fluid runs through the cooler all the time, and it has a removable magnetic plug that catches steel particles.

Let the transmission cool before starting. Put a drain pan under the valve, disconnect the cooler line fittings at the factory valve, remove the old valve and fit the new one in the same location with the supplied sealing rings, using the original cooler line routing. No cutting or programming is needed. Start the engine, check for leaks at every fitting, and set the fluid level using the GM check procedure for the 8L90 with the fluid at operating temperature.