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Ships within 48 hours · Estimated delivery Jul 31 - Aug 5
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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.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
4.4 ★★★★★
Based on 8 reviews
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Product Reviews
★★★★★ 5
I would buy again
Color: White
Great price and works great, very bright and easy to install
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Reviewed in the United States on September 7, 2025
★★★★★ 5
Light Up Your Table
Color: White
Easy to attach and turn on/off
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Reviewed in the United States on July 17, 2025
★★★★★ 5
Affordable
Color: White
Very nice
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Reviewed in the United States on June 17, 2025
★★★★★ 1
Not worth it
Color: White, Color: White
Put new batteries in twice and won’t turn on. Such a waste of money.The brightness is little to none , they were working amazing in the beginning. The picture included is the highest setting and has barely any brightness.
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Reviewed in the United States on September 14, 2025
★★★★★ 5
Excellent lighting
Color: Warm
Highly recommended!
I actually reordered one because I forgot one night to bring it in, then a severe storm came through and stole the umbrella, turning it upside down in the yard. Water got into the battery bays, so they rusted. I'm sure other connections inside rusted too, because after cleaning the contacts, I could not get the light to work again.
But the reason I purchased a new one is because it looks so classy. Its warm light can be adjusted to three levels just by pressing the On button through the levels. Very simple. The ambiance it provides is lovely!
Next to the On button is the clip that flips open to swing open the light. Place the light around the umbrella pole and snap shut the clip. The light is secured, but you can also slide it up or down to whatever height you prefer. It still remains stable and in place until you move it again.
Until I left my first one out in the rain, the light worked beautifully and reliably, as does its replacement. Battery life is excellent unless you forget to turn off the light. I can't tell you exactly how long they last because inevitably after a few weeks, I do forget to turn it off.
This is an inexpensive and beautiful upgrade to your patio experience. Excellent value, excellent quality, excellent lighting.
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Reviewed in the United States on June 19, 2025