BD Diesel 17-19 Chevrolet/GM Allison 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. This Part Fits: Year Make Model Submodel 2017 2019 Chevrolet Silverado 2500 HD High Country