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Ships within 48 hours · Estimated delivery Aug 18 - Aug 23
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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
4.8 ★★★★★
Based on 14 reviews
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Product Reviews
★★★★★ 5
Indestructible
Color: 3PC-Bacon-Brown, Pattern Name: Tough Dog Toys
Finally found a chew bone strong enough for our pit mix, would highly recommend for an agressive chewer! Will buy again
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Reviewed in the United States on June 12, 2026
★★★★★ 5
My four approve
Color: 3PC-Bacon-Brown, Pattern Name: Tough Dog Toys
My dogs, which I have 4, 2 labradors, one Jack Russell and one medium smallish mixed breed dog, all really love the bones. Three of them seem to be vigorous chewers the mixed breed girl being the toughest one on bones. These bones are holding up really well and the dogs really seem to like them. The dogs have not been able to get any big chunks off of the bones so I feel safe letting them have them even when I’m not watching. I would recommend these to Pet owners.
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Reviewed in the United States on May 22, 2026
★★★★★ 3
Size
Color: 3PC-Bacon-Brown, Pattern Name: Tough Dog Toys
I have a medium sized dog and these were to big for him. A bigger dog would love them. Great for chewers.
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Reviewed in the United States on May 23, 2026
★★★★★ 5
Great quality and flavor
Color: 3PC-Bacon-Brown, Pattern Name: Tough Dog Toys
I have two dogs that can chew through everything within a day. Not these, going on four days now, there are signs of wear and tear but still intact. The dogs love the flavor.
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Reviewed in the United States on May 16, 2026
★★★★★ 5
Excellent
Color: 3PC-Bacon-Brown, Pattern Name: Tough Dog Toys
Truly are fantastic! Dogs love these and they last forever
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Reviewed in the United States on May 23, 2026