SKU: 25597115635

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

Sale price$89.95 Regular price$99.95
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Ships within 48 hours · Estimated delivery Aug 17 - Aug 22

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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+ 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 add even more heat dissipation. This 2017+ 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
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Exchange/Return Notes
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SKU: 25597115635

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4.3 ★★★★★
Based on 25 reviews
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Verified Purchase
Mary
Charlottesville, US
★★★★★ 3
The colors are way off
Color: 259 ASH BROWN, Size: 1 Count (Pack of 1)
The ash brown is basically black. However, I do think the gel helps set the brow color and I have been using a ash blonde color and then applying the gel.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on February 9, 2026
J
Verified Purchase
JStewart
Port Orchard, US
★★★★★ 5
So Good!
Color: 262 BLACK BROWN, Size: 1 Count (Pack of 1)
This is my absolute favorite bow pen I've ever tried. The brush tip is incredibly fine and makes each stroke a perfect hair like finish. I tend to get heavy handed with other options like brow powders so having an option for thin hair like stokes makes it incredibly hard to taken it too far. The tip doesn't dry out to the point of skipping or Inconsistency without you knowing its time to refresh it by capping and shaking, but I do find that it comes back refreshed and even better the more you repeat the capping and shaking step between brows. Easy to hold and design. I wasn't totally blown away with the brow gel it comes with attached to the pen when it comes to hold power. It doesn't flake at all and doesn't leave a cast of white or sheen to the brow, which is a plus. It's just a nice way to loosely set the brow after application. There is some wiggle room with wiping the product off with a q tip if a mistake is made, but once the pigment is dry, it doesn't budge all day, even after intense exercise or humid conditions. I'll be repurchased this like... now, and hope it never gets discontinued!
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Reviewed in the United States on April 10, 2024
S
Verified Purchase
Susan Lace
Waukegan, US
★★★★★ 1
Defective product from Amazon.
Color: 255 SOFT BROWN, Size: 1 Count (Pack of 1)
I have used this product many times and I think it is a good product. I usually buy it at Target. The product I received from Amazon was defective. The pen was totally dried out and I was not able to paint a brow. There was liquid in the brush side, but it is colorless and meant to be a finish to make the color last longer. Maybe just a one time fluke, but I'd purchase this elsewhere.
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Reviewed in the United States on June 7, 2026
J
Verified Purchase
Jane Sell
Omaha, US
★★★★★ 5
Eyebrows!
Color: 257 MEDIUM BROWN, Size: 1 Count (Pack of 1)
Great color and great price!
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Reviewed in the United States on April 29, 2026
W
Verified Purchase
waltS
Carnegie, US
★★★★★ 5
Solid edger for the price!
Easy to assemble and works well for my needs edging the driveway and sidewalk! Reasonable price and seems fairly well made so far! I’ve only used it a couple of times but does the job well!
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Reviewed in the United States on May 31, 2026

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