SKU: 48526865078

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 Jul 24 - Jul 29

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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.
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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: 48526865078

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4.1 ★★★★★
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steven whitis
Alexandria, US
★★★★★ 5
Fixes flats and old tires like a charm
Style: 1 gal
This stuff is awesome. If you have tractor tires, ATV tires, bike, tires, hell, any tires that hold air. This stuff is awesome. Awesome. Awesome. It does not work for highway vehicles, i.e. Cars and truck trucks. But anything else it’s great. Dollies, air compressors, wheelbarrows, the stuff is awesome dude.
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Reviewed in the United States on April 5, 2026
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Tim & Tammy
Massapequa, US
★★★★★ 5
slime is and has always been amazing for bike tires and other small pneumatic tires
Style: 1 gal
this is a great value, I have been using slime in my tubes of my bikes and a small inflatable pneumatic tires for probably 30 years, and I can say slime has only improved, and it works fantastic, this is a very good way to save money, and it works great on goat heads and several other ways your tires can get punctured, I still always recommend carrying a small air compressor or pump, but for the price point you just cannot beat slime, every bike shop should always carry this.
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Reviewed in the United States on April 18, 2026
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Verified Purchase
John Quargnenti
Cuba, US
★★★★★ 3
They need to find a better way to ship it
Style: 1 gal
What was left in the bottle worked great. However, the cap was off of the jug when I opened the package. Ididn't have enough for the other tires.
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Reviewed in the United States on March 19, 2026
M
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Michael Kulp
San Leandro, US
★★★★★ 5
Great Spark plugs!
Work Great In My 18.5hp Kohler Engine. The engine is on a Craftsman riding mower, and it drives and runs great.
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Reviewed in the United States on May 7, 2026
K
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Kit Clayton
New York, US
★★★★★ 5
Spark-tacular Revival for My Lawn Chariot
Ordered this OEM 2-pack of Champion spark plugs (Kohler 25 132 23-S / 2513223S) for my Kohler Command K OHV 7000 series (KT725) engine, and let me tell you—these little lightning bolts mean business. Installation? Easier than pretending I’ll read the whole owner’s manual. Pulled the old plugs, threaded these pre-gapped beauties in, torqued appropriately, reconnected, and boom—instant ignition enthusiasm. The engine fired up like it had just downed a double espresso. It’s still too early in the season to mow, but I couldn’t resist a test run. Converted the tractor mower into a full-blown leaf-blasting machine and sent it down my 1/10-mile driveway like a suburban hurricane. Leaves scattered. Neighbors stared. Power was smooth, responsive, and downright smug. Idle is steady. Throttle response is crisp. No sputter, no hesitation—just clean, confident combustion. Exactly what you want from OEM-spec plugs. If your tractor’s been sounding like it’s negotiating with itself before starting, do it a favor. These plugs brought mine back to “runs like a champ”… which, given the name, feels poetically correct. Five stars. Lawn domination pending.
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Reviewed in the United States on February 16, 2026

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