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Ships within 48 hours · Estimated delivery Aug 11 - Aug 16
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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.This Part Fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2017-2019 | Chevrolet | Silverado 2500 HD | High Country |
| 2017-2019 | Chevrolet | Silverado 2500 HD | LT |
| 2017-2019 | Chevrolet | Silverado 2500 HD | LTZ |
| 2017-2019 | Chevrolet | Silverado 2500 HD | WT |
| 2017-2019 | Chevrolet | Silverado 3500 HD | High Country |
| 2017-2019 | Chevrolet | Silverado 3500 HD | LT |
| 2017-2019 | Chevrolet | Silverado 3500 HD | LTZ |
| 2017-2019 | Chevrolet | Silverado 3500 HD | WT |
| 2017-2019 | GMC | Sierra 2500 HD | Base |
| 2017-2019 | GMC | Sierra 2500 HD | Denali |
| 2017-2019 | GMC | Sierra 2500 HD | SLE |
| 2017-2019 | GMC | Sierra 2500 HD | SLT |
| 2017-2019 | GMC | Sierra 3500 HD | Base |
| 2017-2019 | GMC | Sierra 3500 HD | Denali |
| 2017-2019 | GMC | Sierra 3500 HD | SLE |
| 2017-2019 | GMC | Sierra 3500 HD | SLT |
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
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]
- Please click here for more details>>> Return & Exchange Policy
4.1 ★★★★★
Based on 16 reviews
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Product Reviews
★★★★★ 5
Almost blew up my microwave
Size: 20 Ounces, Size: 20 Ounces
TL;DR "A hilarious microwave mistake turned into a great home cafe upgrade. This 20oz cup is straightforward to handle, looks incredibly professional, and holds a level of heat that will literally burn you if you aren't careful."
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Bought this for homemade coffee brewing, just to spice things up. But as I go ahead to heat up my new shiny stainless steel milk frother cup in the microwave, whoopdy doo. Ya can’t put stainless in the microwave! Regardless, it’s still a straightforward frother cup to handle, making it a great dollar investment for upgrading my home cafe setup.
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1. Spotless Stainless Steel: Its sleek appearance made me feel professional in the hands of an amateur like moi. Great quality!
2. Temperature Retention: I accidentally burnt myself because it stayed so hot, but that is a major positive. Proving the insulation works perfectly and keeps the milk piping hot.
3. Size: The 20oz capacity is accurate, providing the perfect amount of space for frothing without any overflow.
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Reviewed in the United States on June 6, 2026
★★★★★ 5
Sturdy
Size: 20 Ounces
Great pitcher
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Reviewed in the United States on January 20, 2026
★★★★★ 4
Decent pitcher
Size: 11.8 Ounces
Smaller than expected. I frothed 5 oz of milk and it was almost a mess.
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Reviewed in the United States on October 16, 2025
★★★★★ 5
Love
Size: 11.8 Ounces
Perfect size for making my Fredo cappuccino every morning. Throw it in the dishwasher look brand new everytime
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Reviewed in the United States on December 18, 2025
★★★★★ 5
Very nice product. Made of high quality.
Size: 20 Ounces
Product is just what i ordered. Recommend to anyone to purchase from this vendor.
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Reviewed in the United States on November 12, 2025