Mishimoto 2017+ GMC 6.6L Duramax L5P Transmission Thermal Bypass Valve Kit
SKU: 95731147738

Mishimoto 2017+ GMC 6.6L Duramax L5P Transmission Thermal Bypass Valve Kit

Sale price$89.99 Regular price$99.99
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  • USA
  • CAN

Ships within 48 hours · Estimated delivery Jul 8 - Jul 13

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Description

Mishimoto 2017+ GMC 6.6L Duramax L5P Transmission Thermal Bypass Valve KitThe 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

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 full-flow thermal bypass valve upgrade for your 2017-2019 Chevrolet/GMC 6.6L Duramax. Our CNC-machined aluminum full-flow thermal bypass valve not only looks better than the stock unit, but it performs better too. This Mishimoto thermal bypass valve eliminates the internal thermostat, providing full fluid flow to the transmission cooler in all running conditions. This setup is ideal for owners in warm climates, those performing heavy towing, and trucks needing the best possible cooling efficiency for their transmission. 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 adds even more heat dissipation. This 2017-2019 Chevrolet/GMC 6.6L Duramax L5P Full-Flow Thermal Bypass Valve Kit is built to last a lifetime with a durable black anodized finish and our Mishimoto Lifetime Warranty.
Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
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  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 95731147738

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Phillip
Carnegie, US
★★★★★ 5
Works for hiding cables
Color: Black, Size: Standard
Worked great to manage my cables to my pc setup. My double wide surge protector fit in there just right. Easy to mount with the holes and the bottom to fit a screw driver or power drill. Not too flimsy.
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Reviewed in the United States on March 30, 2026
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TYB FET
San Leandro, US
★★★★★ 5
Sturdy and big
Color: White, Size: Extra Deep
Worked perfect. Sturdy and fit the UPS we are using
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Reviewed in the United States on May 8, 2026
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Minh
West Palm Beach, US
★★★★★ 5
N/A
Color: Black, Size: Standard, Color: Black, Size: Standard
Clean Looking,
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Reviewed in the United States on May 13, 2026
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Summer C
Chelsea, US
★★★★★ 5
Got the job done
Color: Black, Size: Standard
Solid product. Fast delivery
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Reviewed in the United States on January 12, 2026
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L.K.
West Palm Beach, US
★★★★★ 5
High quality, reliable
Model: Pop up outlet-black
The units looked really cool and were of excellent quality. They popped up reliably albeit slowly which was fine with me. I was really looking forward to using these in a built in cabinet we're making but they did not fit where I wanted them so I had to send them back. I would buy these again if I ever had a project that needed them.
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Reviewed in the United States on December 12, 2025

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