SKU: 73309385794

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
  • USA
  • CAN

Ships within 48 hours · Estimated delivery Jul 20 - Jul 25

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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
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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: 73309385794

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Jack J
Chelsea, US
★★★★★ 5
Works well
Size: 1+6+6 Pack
Fit perfect
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Reviewed in the United States on March 11, 2026
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liliana g.
Belleville, US
★★★★★ 5
Fits and works fine
Size: 1+6+6 Pack
Its a good deal for all the things it comes with.
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Reviewed in the United States on November 17, 2025
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margarida santos
Waukegan, US
★★★★★ 4
Easy to use.
Size: 2+6+1+12 Pack
They work very well.
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Reviewed in the United States on March 8, 2026
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just bookstore
Chelsea, US
★★★★★ 5
Not so good
Size: 2+6+1+12 Pack
These placement filters are not as good as the original. They seem to hold onto the debris & don't release it into the reservoir. I clean the filter & reservoir after each use & always find the filter full & the reservoir nearly empty.
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Reviewed in the United States on December 24, 2025
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Van&Car
Houston, US
★★★★★ 5
Well priced
Size: 1+6+6 Pack
Very economically priced set of replacement parts for Eufy RoboVac 11S Max
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Reviewed in the United States on January 25, 2026

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