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 18 - Jul 23

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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.       


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Exchange/Return Notes
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SKU: 10133814327

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BRENDA J.
Dallas, US
★★★★★ 5
Saved on DIY
Fit my 2021 Civic perfectly and with you tube video easy to install
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Reviewed in the United States on February 22, 2026
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Anthony
Phoenix, US
★★★★★ 5
Ease of use and price
Easy, good filters, good price never go to a dealer for them, literally took me 5 minutes to do both.
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Reviewed in the United States on November 22, 2025
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Samster79
Phoenix, US
★★★★★ 5
Great Value
Item came as described and fit perfectly paid the price I usually pay for the engine filter for both engine and cabin filter definitely would recommend.
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Reviewed in the United States on December 8, 2025
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Sky
Carnegie, US
★★★★★ 5
Great little bang for buck and DIY savings from the Dealership Service DEPT
Easy to install and very simple to place into the correct compartments in the glove box and engine bay. Took maybe 15 minutes or less. Quality is great and the air in the cabin is so fresh now! The quality of the air filters is OEM+ which is great when trying to save some money and add value to the product. Fits perfectly in my 2020 Honda civic Sedan. Includes everything needed to replace both filters. Includes both cabin and engine air filter
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Reviewed in the United States on June 1, 2026
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J A
Massapequa, US
★★★★★ 5
Fits 2017 Honda Civic
This fit perfect for my 2017 Honda Civic. It looks and feels super similar to the ones I removed so they seem of equal quality. As for value? Can't beat it!
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Reviewed in the United States on August 29, 2025

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