BD Diesel 19-23 Chevrolet Silverado / GMC Sierra 1500 8L90 Cooler Bypass DeleteDebris in the stock cooler bypass valve can cause it to jam the internal valve, keeping it in recirculation mode. When this happens, the transmission temperature will rise, which can lead to overheating and premature transmission failure. The BD Cooler Bypass Delete keeps the transmission cooler operational all the time and eliminates this failure prone item.