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
  • USA
  • CAN

Ships within 48 hours · Estimated delivery Aug 10 - Aug 15

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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.
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  • 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: 95731147738

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4.5 ★★★★★
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Nicholas K
Birmingham, US
★★★★★ 5
Great filter
Size: AF259
This fit my Mazda CX-5 perfectly. I'm happy with the seal and quality. Great price. I will certainly reorder for my next replacement.
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Reviewed in the United States on May 19, 2026
A
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Amazon Customer
Cuba, US
★★★★★ 5
Great fit and quality
Size: AF113
Not a complicated product, but after going to 2 different auto parts stores and this not being in stock, Amazon to the rescue. Arrived the next day and the quality is definitely on par with “store brand” ones from retailers. Definitely cheaper as well.
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Reviewed in the United States on April 23, 2026
A
Verified Purchase
AC
Port Orchard, US
★★★★★ 5
Fit my 2014 Accord perfectly
Size: AF476
Seems to be the same quality as OEM. Fit perfectly. Easy to install.
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Reviewed in the United States on April 24, 2026
B
Verified Purchase
Becca
Battle Creek, US
★★★★★ 4
Affordable priced. Fits well
Size: AF377
They work good in my 2019 Toyota RAV4
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Reviewed in the United States on May 11, 2026
M
Verified Purchase
MarkC
Whiting, US
★★★★★ 5
Perfect fit, slid right into place and locked like it should
Size: AF943
Wanting to correct my previous review (I reviewed the incorrect item). This product fit perfectly in my vehicle- my apologies for the first review; perhaps Amazon or the vendor can replace the first review with this one. I am very pleased with this item.
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Reviewed in the United States on May 15, 2026

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