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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.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
4.5 ★★★★★
Based on 18 reviews
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Product Reviews
★★★★★ 5
Excellent value for money!
Size: 934W-Z, Color: Black, Size: 934W-Z, Color: Black
I absolutely love this office chair! I needed a chair that could support my standing desk without sacrificing comfort, and this one completely exceeded my expectations. It's incredibly sturdy and durable, well-made, and the height adjustment is super convenient, making it easy to find the perfect fit. Even during long hours of work, the seat is comfortable, and the ergonomic design effectively reduces pressure on my back and legs. I love its clean, modern look—it fits my home office perfectly. Assembly was quick and easy, and for this price, the quality is absolutely fantastic!
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Reviewed in the United States on February 24, 2026
★★★★★ 5
Perfect chair!
Size: 934-Z, Color: Blue, Size: 934-Z, Color: Blue
I have an adjustable-height desk (also purchased from Amazon) and needed a drafting chair for those times when my body gets tired of standing. This chair fits the bill and then some! I put it together myself; it took me about an hour, but would take me about half that next time, since now I know what to do (and what NOT to do!). All the parts were there; there are even spare parts (see photo). All the holes were drilled in exactly the right places, too, which isn't always the case when I buy things from Amazon (my standing desk is a great example). The chair fits me; I'm short (5'3.5"), and often the seats of furniture are too deep for me to rest my feet flat on the floor. The depth of the seat on this chair is just a little over 18 inches, and with the adjustable footrest ring, it's perfect. I don't think a tall or heavy person would fit in it, to be honest. But it's perfect for those of us who are vertically challenged. I love that it glides easily on my hardwood floors and that it turns 360 degrees. The chair comes in numerous luscious colors, so take your pick! It is very sturdy, has good lumbar support, and the seat and seat back are very comfortable. And the arms flip up, which was an absolute must when I was shopping for this chair. I got it on sale, too -- $109.00 -- and I'm delighted with this purchase.
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Reviewed in the United States on April 23, 2026
★★★★★ 5
Excellent adjustable drafting chair
Size: 934-Z, Color: Blue
Excellent chair design, extremely comfortable and exceptionally easy instructions to follow making for simple assembly. Love the amply wide cushioned seat and ergonomic backrest. The height adjustment feature works perfectly as well as positioning of the foot ring . Having the ability to raise the arms is also a big plus! I highly recommend this product for attractive appearance, comfort features, functionality and operation. Really nice chair!
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Reviewed in the United States on April 13, 2026
★★★★★ 4
Comfortable, stylish, and perfect for long work hours 💗✨
Size: 934-Z, Color: Pink
I bought this chair because I spend a lot of time working and needed something comfortable but also stylish, and I absolutely love it.
Since I started using it, I feel much better support in my back thanks to the lumbar support. It makes a big difference, especially during long work hours. The adjustable footrest is also a feature I didn’t know I needed, but now I use it all the time.
The flip-up armrests are very convenient because I can adjust them depending on what I’m doing or move them out of the way when needed.
The pink color is beautiful and adds a soft, elegant touch to my workspace. It looks great in a modern home office.
It feels sturdy, well-made, and very stable. Overall, it’s a great purchase that improved both my comfort and the look of my workspace.
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Reviewed in the United States on April 29, 2026
★★★★★ 5
All-around thumbs up!
Size: 934W-Z, Color: Black
So far, so awesome. Easy to assemble, comfortable, arrived quickly and is exactly what I was looking for. I have a tall work bench in my new studio so I needed a chair that we could allow me to sit higher than a regular office chair and allow me to get off my feet after standing on the concrete floor. Plus its a nice looking chair that I am sure will last a long time. I love the flip-up arms and the lumbar support. This is just right!
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Reviewed in the United States on May 8, 2026