High Flow Transmission Thermal Bypass Valve Kit for 2017–2025 Chevrolet and GMC trucks with Silverado/Sierra 2500HD and 3500HD equipped with the 6.6L L5P Duramax diesel and Allison transmission. This kit eliminates the internal thermostat, providing full fluid flow to the transmission cooler in all running conditions. Strategically machined internal passages provide improved flow over the stock valve for more effective cooling, and cooling fins machined into the valve body add even more heat dissipation.

Fitment

• 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 2025 Chevrolet/GMC Silverado/Sierra 2500HD and 3500HD -- 6.6L L5P Duramax Diesel

Product Details

• Construction: CNC-machined aluminum thermal bypass valve
• Finish: Black anodized
• Fittings: Two 7/8-inch X 14 quick-disconnect transmission line fittings
• Features: Includes removable thermostat for fast warm-up in cold climates and thermostat bypass for constant cooling in warm climates or extreme driving/towing conditions
• Installation: Fits with stock transmission cooler piping, requiring no modification for installation
• Heat Management: Strategically machined internal passages and integrated heat-sink fins provide improved flow and added heat dissipation over stock units
• Warranty: Mishimoto Lifetime Warranty

Installation

Direct fit for 2017+ Chevrolet/GMC 6.6L Duramax L5P with stock transmission cooler piping requiring no modification. Installation is straightforward and can be completed by a technician in under one hour.

Check local emissions regulations before purchase. Professional installation is recommended.

Get the right part the first time.