SKU: 10133814327

Mishimoto Transmission Thermal Bypass Valve Kit 17-19 GM 6.6L Duramax L5P

Sale price$133.16 Regular price$147.95
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Ships within 48 hours · Estimated delivery Jul 14 - Jul 19

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Description

Mishimoto Transmission Thermal Bypass Valve Kit 17-19 GM 6.6L Duramax L5PAre you wanting the best performance out of your Transmission? 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

Are you wanting the best performance out of your Transmission? 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. 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.

OPTIONAL THERMOSTAT DETAILS: This kit includes the removeable Thermostat 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.       


Shipping Notes
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Exchange/Return Notes
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SKU: 10133814327

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Clara
Grantham, US
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Tal como la imagen
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Reviewed in the United States on February 5, 2026
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Kody
Lake Worth, US
★★★★★ 1
Bad quality overall
Terrible quality, has melted plastic, does not fit at all. Please avoid this.
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Leo I.
Chelsea, US
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Clean
Look really clean I just need the side markers now
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Giovany Gil
Houston, US
★★★★★ 2
Won’t fit like oem
It doesn’t fit well and had to modify it to get it as close as possible
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Reviewed in the United States on February 1, 2026
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Miguel R.
Dallas, US
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Look good :)
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Good fitment, looks nice. The grill is easier to remove using a pick tool, no need to remove the bumper.
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Reviewed in the United States on October 20, 2025

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