SKU: 3942758100

Mishimoto 2017+ GMC 6.6L Duramax L5P Transmission Thermal Bypass Valve Kit

Sale price$133.16 Regular price$147.95
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  • USA
  • CAN

Ships within 48 hours · Estimated delivery Jul 18 - Jul 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 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.
Shipping Notes
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Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
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SKU: 3942758100

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4.7 ★★★★★
Based on 22 reviews
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A
Verified Purchase
Amazon Customer
Louisville, US
★★★★★ 5
Perfect Kit For Cold Brew Coffee or Teas
Size: 32 Ounces, Color: Gray
I make coffee many different ways and have been doing cold brew in a regular mason jar without a filter. I just got this set up and am very pleased. The kit comes with a thick glass mason jar of good quality, a filter basket and a lid that fits on top of a wide mouth mason jar. The lid has a sturdy handle attached to it and a secure pour spout with its own snap tight cover. This is a perfect set up for cold brewing coffee. I filled the jar with water and secured the lid. I shook it up and turned it upside down and there were no leaks so it will be safe from accidental tip overs. If you are looking for an easy way to make cold brew coffee then I strongly recommend this simple set up. It is shaped just like a regular Mason jar with a pour spout lid so it can fit almost anywhere a Mason jar will fit. This also looks to be good for making small batches of sun tea with loose leaf tea. Enjoy!
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Reviewed in the United States on April 10, 2026
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Verified Purchase
Nema
Whiting, US
★★★★★ 5
Great hot or cold Brewer I ❤️🙏✝️
Size: 64 Ounces, Color: Gray
This works great for either cold or hot coffee or tea. Mine has had a workout since the day I received it. Easy to use and clean. Give me a a few weeks to check on the durability.
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Reviewed in the United States on April 8, 2026
D
Verified Purchase
David W. Furstenau
Phoenix, US
★★★★★ 4
So close to perfect.
Size: 64 Ounces, Color: Orange
I'm enjoying the hell outa this. On my third batch in a week. No, you don't really need one to make cold brew. You could probably scrounge up everything you need in a reasonably well-stocked kitchen. But it really makes things so much easier. And it cleans up nicely. I might even buy another (I drink a lot of ice coffee in the summer). The ONLY drawback is the cheap, plastic screw-on lid. I don't trust it. I'd pay $10 bucks more for a metal lid. So, we'll take one star back.
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Reviewed in the United States on February 14, 2026
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Verified Purchase
Kady
Whiting, US
★★★★★ 5
Excellent Product
Size: 64 Ounces, Color: Gray
Absolutely love this item! It was securely packaged and arrived beautifully. It is super easy to use, very sturdy, has no issues leaking, a slim and sleek shape that fits perfectly in my fridge shelf, the solid glass jar and thick, durable plastic makes this item absolutely perfect. 10/10 recommend
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Reviewed in the United States on April 25, 2026
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Verified Purchase
Amazon Customer
Houston, US
★★★★★ 5
Great cold brew at home save yourself some money get it now
Size: 64 Ounces, Color: 2Pack-Gray
This is a great way to make cold brew at home. I love the look, and size fits in the fridge perfectly. The system could not be any easier to use put coffee in, and put it in the fridge. The glass seems to be normal mason jar thickness and the handle is nice and sturdy. Very nicely made for the price.
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Reviewed in the United States on May 15, 2026

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