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 Aug 14 - Aug 19

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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
  • Free Standard Shipping on $100+ Orders 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]
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SKU: 3942758100

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4.4 ★★★★★
Based on 22 reviews
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Scraps
Chelsea, US
★★★★★ 4
Good at price
Size: 9 Wide, Color: Sand
Fit a little small at my big toe but otherwise fit well. Heel rubbed slightly first 5 hour wear but no blister.
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Reviewed in the United States on May 9, 2026
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Lynn
Pawtucket, US
★★★★★ 5
Lightweight comfortable at a good price!
Size: 10.5, Color: Navy
These shoes are perfect. The color matches my navy outfits as well as my denim. They are comfortable and they look great. They are easy to pack lightweight and a great value. I am extremely satisfied and highly recommend!
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Reviewed in the United States on June 3, 2026
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PHOEBES
Los Angeles, US
★★★★★ 3
REALLY CUTE SHOE BUT CUT WAY TOO SMALL!
Size: 8, Color: Black Patent
I received the black patent leather shoes today and they are so cute! Sadly I need to return them because they are cut way too small. I normally wear a 7.5 or 8 on dress shoes so I ordered the 8. They are so tight across the top that it's uncomfortable as soon as I put them on. They are smaller than a normal size 8 dress shoe. The big toe area is extremely uncomfortable because it doesn't allow any room for it at all, so my big toe just presses against the side and end of the shoe without even walking in them. I have very narrow feet and these still are too small for me. So I am returning them and I already ordered a 8.5 W and hope that will fit much better. The patent leather is very cute and adds just enough dressy that I can wear them with slacks or my Capri jeans. I like the slip on and the cushion foot bed because it feels soft.
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Reviewed in the United States on May 26, 2026
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Verified Purchase
Amazon Customer
Belleville, US
★★★★★ 5
Love these flats!
Size: 9 Wide, Color: Black White Faux Snake Skin, Size: 9 Wide, Color: Black White Faux Snake Skin
One of my favorite pair of flats! I’ve had these for several years and they are still comfortable, in good shape and really add a little spice to my outfits. I can wear these all day and not have any foot pain or discomfort as a result. The quality is good, fit is perfect and I tend to have difficulty with shoes due to bunions. Love these!!
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Reviewed in the United States on May 23, 2026
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lunaposas
San Leandro, US
★★★★★ 5
LOVE LOVE.
Size: 7.5 Wide, Color: Beige
I love these shoes so much I had to write a review. So comfortable. Cushioned. Fits perfectly especially if you are more on the wide side. They are soft. Flexible. Easy slip ons you can walk around in all day. I want to try more colors.
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Reviewed in the United States on June 4, 2026

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