The Allison transmission is the backbone of your L5P Duramax. It's responsible for transmitting large quantities of torque from your V8 diesel powerplant. This torque generates a lot of heat, and if that heat isn't dissipated, it can destroy your transmission. The transmission cooler does a good job of keeping trans fluid temperatures in check, but only if the fluid can reach it.
The stock cooling system of the Allison 1000 transmission utilizes an in-line thermal bypass valve that controls fluid flow to the transmission cooler. The purpose of this valve is to prevent transmission fluid from flowing to the cooler until it reaches operating temperature. The thermostat inside this valve is prone to failure, however, and when that happens, the fluid never flows to the cooler, and the transmission can overheat. That's why Mishimoto has developed a thermal bypass valve upgrade for your 2017+ Chevrolet/GMC 6.6L Duramax.
Our CNC-machined aluminum thermal bypass valve not only looks better than the stock unit, but it performs better too. This Mishimoto thermal bypass valve kit includes a fully serviceable thermostat for fast warm-up in cold climates. This kit also includes a thermostat bypass that can be installed to provide constant cooling in warm climates or for use in extreme driving/towing conditions. The Mishimoto thermal bypass valve features strategically machined internal passages, providing improved flow over the stock valve for more effective cooling. In addition, cooling fins machined into the valve body add even more heat dissipation.
This 2017+ Chevrolet/GMC 6.6L Duramax L5P Thermal Bypass Valve Kit is built to last a lifetime with a durable black anodized finish and our Mishimoto Lifetime Warranty.
Fitment:
2017 Chevrolet Silverado 2500 HD High Country
2017 Chevrolet Silverado 2500 HD LT
2017 Chevrolet Silverado 2500 HD LTZ
2017 Chevrolet Silverado 2500 HD WT
2017 Chevrolet Silverado 3500 HD High Country
2017 Chevrolet Silverado 3500 HD LT
2017 Chevrolet Silverado 3500 HD LTZ
2017 Chevrolet Silverado 3500 HD WT
2017 GMC Sierra 2500 HD Base
2017 GMC Sierra 2500 HD Denali
2017 GMC Sierra 2500 HD SLE
2017 GMC Sierra 2500 HD SLT
2017 GMC Sierra 3500 HD Base
2017 GMC Sierra 3500 HD Denali
2017 GMC Sierra 3500 HD SLE
2017 GMC Sierra 3500 HD SLT
2018 Chevrolet Silverado 2500 HD High Country
2018 Chevrolet Silverado 2500 HD LT
2018 Chevrolet Silverado 2500 HD LTZ
2018 Chevrolet Silverado 2500 HD WT
2018 Chevrolet Silverado 3500 HD High Country
2018 Chevrolet Silverado 3500 HD LT
2018 Chevrolet Silverado 3500 HD LTZ
2018 Chevrolet Silverado 3500 HD WT
2018 GMC Sierra 2500 HD Base
2018 GMC Sierra 2500 HD Denali
2018 GMC Sierra 2500 HD SLE
2018 GMC Sierra 2500 HD SLT
2018 GMC Sierra 3500 HD Base
2018 GMC Sierra 3500 HD Denali
2018 GMC Sierra 3500 HD SLE
2018 GMC Sierra 3500 HD SLT
2019 Chevrolet Silverado 2500 HD High Country
2019 Chevrolet Silverado 2500 HD LT
2019 Chevrolet Silverado 2500 HD LTZ
2019 Chevrolet Silverado 2500 HD WT
2019 Chevrolet Silverado 3500 HD High Country
2019 Chevrolet Silverado 3500 HD LT
2019 Chevrolet Silverado 3500 HD LTZ
2019 Chevrolet Silverado 3500 HD WT
2019 GMC Sierra 2500 HD Base
2019 GMC Sierra 2500 HD Denali
2019 GMC Sierra 2500 HD SLE
2019 GMC Sierra 2500 HD SLT
2019 GMC Sierra 3500 HD Base
2019 GMC Sierra 3500 HD Denali
2019 GMC Sierra 3500 HD SLE
2019 GMC Sierra 3500 HD SLT
2020 Chevrolet Silverado 2500 HD High Country
2020 Chevrolet Silverado 2500 HD LT
2020 Chevrolet Silverado 2500 HD LTZ
2020 Chevrolet Silverado 2500 HD WT
2020 Chevrolet Silverado 3500 HD High Country
2020 Chevrolet Silverado 3500 HD LT
2020 Chevrolet Silverado 3500 HD LTZ
2020 Chevrolet Silverado 3500 HD WT
2020 GMC Sierra 2500 HD Base
2020 GMC Sierra 2500 HD Denali
2020 GMC Sierra 2500 HD SLE
2020 GMC Sierra 2500 HD SLT
2020 GMC Sierra 3500 HD Base
2020 GMC Sierra 3500 HD Denali
2020 GMC Sierra 3500 HD SLE
2020 GMC Sierra 3500 HD SLT
2021 Chevrolet Silverado 2500 HD Custom
2021 Chevrolet Silverado 2500 HD High Country
2021 Chevrolet Silverado 2500 HD LT
2021 Chevrolet Silverado 2500 HD LTZ
2021 Chevrolet Silverado 2500 HD WT
2021 Chevrolet Silverado 3500 HD High Country
2021 Chevrolet Silverado 3500 HD LT
2021 Chevrolet Silverado 3500 HD LTZ
2021 Chevrolet Silverado 3500 HD WT
2021 GMC Sierra 2500 HD Base
2021 GMC Sierra 2500 HD Denali
2021 GMC Sierra 2500 HD SLE
2021 GMC Sierra 2500 HD SLT
2021 GMC Sierra 3500 HD Base
2021 GMC Sierra 3500 HD Denali
2021 GMC Sierra 3500 HD SLE
2021 GMC Sierra 3500 HD SLT
