SKU: 79711077414

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

Sale price$133.19 Regular price$147.99
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  • USA
  • CAN

Ships within 48 hours · Estimated delivery Aug 12 - Aug 17

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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 thermal bypass valve upgrade for your 2017-2019 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 adds even more heat dissipation. This 2017-2019 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.
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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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]
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SKU: 79711077414

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Jocko
Louisville, US
★★★★★ 5
Very Comfortable Shoes
Size: 11, Color: Black Full Grain
Were purchased as a gift and the wearer says they are the most comfortable shoes he has
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Reviewed in the United States on December 28, 2025
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DALIA ALVAREZ
Boise, US
★★★★★ 5
Great shoes
I like these shoes they are comfortable, and look great. Good quality, it fits to its size.
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Reviewed in the United States on May 19, 2025
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Leonardo Perez
Houston, US
★★★★★ 1
Mal presentado
Size: 9, Color: Black Full Grain
Un zapato llego con cosido defectuoso
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Reviewed in the United States on October 29, 2025
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Joe
Carnegie, US
★★★★★ 5
Comfortable
Size: 11.5, Color: Black Full Grain
Fit great very comfortable
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Reviewed in the United States on October 16, 2025
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DAVID L.
Boise, US
★★★★★ 5
Nice shoes!
Size: 11, Color: Black Full Grain
I bought them in black and I like them so much I will be buying the brown soon. They fit true to size and are comfortable and stylish. I like the clean simplicity. They're basically a dressy sneaker which is perfect for my job's 'dress code'. Yet they're stylish enough to be worn weekends or a night out. They seemed just a touch stiff out of the box but IMO that's completely normal and fine - after just a couple days of wearing them they are breaking in nicely. No complaints on that. They seem to be of very high quality and I'm very happy with them.
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Reviewed in the United States on February 8, 2026

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