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- USA
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Ships within 48 hours · Estimated delivery Jul 4 - Jul 9
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For Your Every Summer RSVP, with Code: SUMMER15
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+ 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 add even more heat dissipation. This 2017+ 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 |
|---|---|---|---|
| 2021 | Chevrolet | Silverado 2500 HD | Custom |
| 2017-2021 | Chevrolet | Silverado 2500 HD | High Country |
| 2017-2021 | Chevrolet | Silverado 2500 HD | LT |
| 2017-2021 | Chevrolet | Silverado 2500 HD | LTZ |
| 2017-2021 | Chevrolet | Silverado 2500 HD | WT |
| 2017-2021 | Chevrolet | Silverado 3500 HD | High Country |
| 2017-2021 | Chevrolet | Silverado 3500 HD | LT |
| 2017-2021 | Chevrolet | Silverado 3500 HD | LTZ |
| 2017-2021 | Chevrolet | Silverado 3500 HD | WT |
| 2020-2021 | GMC | Sierra 2500 HD | AT4 |
| 2017-2021 | GMC | Sierra 2500 HD | Base |
| 2017-2021 | GMC | Sierra 2500 HD | Denali |
| 2017-2021 | GMC | Sierra 2500 HD | SLE |
| 2017-2021 | GMC | Sierra 2500 HD | SLT |
| 2020-2021 | GMC | Sierra 3500 HD | AT4 |
| 2017-2021 | GMC | Sierra 3500 HD | Base |
| 2017-2021 | GMC | Sierra 3500 HD | Denali |
| 2017-2021 | GMC | Sierra 3500 HD | SLE |
| 2017-2021 | 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
4.6 ★★★★★
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Product Reviews
★★★★★ 5
It's a gift
Color: 9910: All Gold
Looks good.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 15, 2026
★★★★★ 5
Great for everyday wear, vibrant dial, comfy band, no locking crowns. Would buy again.
Color: 6638: Gold band & Green dial
Excellent price point, stylish, and the pictures match what you get. The green is bright and vibrant and the gold band looks real although stainless. A great piece to wear all the time without worrying about losing value. Would buy again. My biggest complaint: The small crown do not lock so they get randomly hit and cant be trusted. The time kept is fine but do no expect to be able to lock the days in. The crown wont spin to lock them.
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Reviewed in the United States on October 6, 2025
★★★★★ 5
Es una belleza de reloj
Color: 6638: Gold band & Gold dial
Hermoso tal como se describe en la imagen
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Reviewed in the United States on April 29, 2026
★★★★★ 4
Looks really good.
Color: 6638: Gold band & Gold dial
Looks great, quality is really good too. Only downfall is that if you don't wear it everyday, you will have to wind it up and move it to get the second hand moving again and then set the time again i can get mine sit for a whole day without resetting time but by day two it has to be reset. Even with that, it's a great watch. Have gotten lots of compliments.
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Reviewed in the United States on January 2, 2026
★★★★★ 5
Best quality for the price!
Color: 9910: All black
For the price all these Olevs watches are bad ass!! I have 3 of them.
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Reviewed in the United States on December 19, 2025