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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:
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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]
- Please click here for more details>>> Return & Exchange Policy
4.5 ★★★★★
Based on 18 reviews
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Product Reviews
★★★★★ 5
My dogs fight over it
Color: Orange, Color: Orange
Easy to use, durable, and has a great battery love. At first my dogs were curious and unsure about it, now its become one of their favorite toys. They'll stare at it while its being charged and impatiently wait for it so they can have fun again. Perfect size for most breeds.
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Reviewed in the United States on January 3, 2026
★★★★★ 5
Great dog birthday gift
Love it. Is it the best ball ever? No. I love it because my dog can find it if he lost track of it while I was poorly throwing the ball. Also, if it starta getting dark out and he has it in his mouth, I know exactly where he is.
The glow is great! Pretty bright, changes colors, activatws after a hard bounce.
Changing the battery is easy and just takes a screwdriver.
Bounce is pretty good.
Dog really likes it. He likes things that glow.
It has held up so far, and one of the other dogs, who likes to destroy things, got ahold of it. He is working on not wrecking things, but I know he tried for a little bit and there has been no damage.
The ball does have quite a bit of heft to it, so a small-ish dog isn't going to like the size or weight, likely.
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Reviewed in the United States on April 21, 2026
★★★★★ 5
Freaking works great !
Met and exceeded my expectations! It's very durable , it has become my dogs favorite ball, it is easily seen in the snow, and at night!!
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Reviewed in the United States on January 6, 2026
★★★★★ 5
A bit pricey, but then again, our new inflated economy
Nite Ize makes great products. I especially like the extended time the ball stays lit. Especially for those times the dog decides not to retrieve and you're searching the ground for the ball in the dark.
It's heavy. Good for power chewers. Not a lot of bounce but then again the light function is the primary goal.
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Reviewed in the United States on December 31, 2025
★★★★★ 1
Stopped working the 2nd day
I realize I am the minority. This ball has great reviews. So it has to just be my bad luck. But it worked great the 1st day. Had some problems with getting it to turn on the next day. After that it never came on again. I bought new batteries and put 2 new batteries in it. It still did not light up. Other than that, it’s great and seems durable. I just can’t get the lights to work on it.
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Reviewed in the United States on March 11, 2026