SKU: 37194769079

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

Sale price$148.49 Regular price$164.99
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Ships within 48 hours · Estimated delivery Aug 4 - Aug 9

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For Your Every Summer RSVP, with Code: SUMMER15

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 2017-2019 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 adds even more heat dissipation. This 2017-2019 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.

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.
  • Except Preorder products are shipped in 48 hours.
  • Delivery 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: 37194769079

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Serina Anthony
Pawtucket, US
★★★★★ 5
Fun alternative to traditional tuxedo
Size: Large, Color: Black-2 Pieces, Size: Large, Color: Black-2 Pieces
Fairly good quality. Hubby wore this as fun alternative to his regular tux in a cruise elegant night. Looked sharp and we even got family pictures in it.
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Reviewed in the United States on September 13, 2025
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Octavia Ward
Lowell, US
★★★★★ 5
Great for price ⭐
Size: Small, Color: Blue-2 Pieces, Size: Small, Color: Blue-2 Pieces
Bought this for my son's junior prom and it looked so good on him. I had to get a few alterations done because it was a bit too big for him but all in all great quality for the price.
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Reviewed in the United States on June 8, 2025
J
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Jennifer
New York, US
★★★★★ 5
Quality suit at an amazing price!
Color: Black, Size: Large, Color: Black, Size: Large
This suit was perfect for my son’s senior prom. Quality material and fit him perfectly! This was ideal when you don’t want to rent a tuxedo, knowing he will use it again and again. He looked so very handsome.
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Reviewed in the United States on May 24, 2026
A
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AW
Grantham, US
★★★★★ 5
Great suit!
Color: Black, Size: Small
Great suit! Suit is well made for the price. Very comfortable, nice material and could be worn for any occasion no matter the time of year. We ordered according to the size chart and fit great! Would be easy to do a little tailoring if needed tho. Came in quick and is exactly what we needed. Will be ordering other colors for the future!
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Reviewed in the United States on April 29, 2026
K
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Ken
Port Orchard, US
★★★★★ 5
XS great fit very pleased!! 5’8”-5’9” 140 lbs
Color: Dark Grey, Size: X-Small
My son is wearing this to prom he is about 5’8”-5’9” all muscle 140 lbs and I had to order an xs in grey. The small jacket was good but the pants were to big/baggy. The quality is nice and wow the fit is great!!! So pleased. I will try to update later with a picture
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Reviewed in the United States on April 24, 2026

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