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- USA
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- USA
- CAN
Ships within 48 hours · Estimated delivery Jul 8 - Jul 13
Promo Codes Available:
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:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
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]
- Please click here for more details>>> Return & Exchange Policy
4.3 ★★★★★
Based on 1830 reviews
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Product Reviews
★★★★★ 5
Adorable, well-made suit—perfect for special occasions 🤵✨
This suit exceeded my expectations! The color is beautiful and looks even better in person—perfect for weddings, parties, or any formal event. My son looked so sharp and received so many compliments.
The fabric feels lightweight and breathable, which is great for warmer weather. It doesn’t feel stiff or uncomfortable, so he was able to move around easily all day. The set comes with everything you need—the jacket, vest, pants, and tie—making it a great value.
I also appreciate the adjustable waistband on the pants, which helped get a better fit. Overall, the suit looks very polished and high-quality without the high price tag.
Only small note: since it’s linen, it can wrinkle a bit, so you may want to lightly steam it before wearing.
Overall, a fantastic outfit for any formal occasion—definitely recommend!
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Reviewed in the United States on March 21, 2026
★★★★★ 5
Sharp Linen Suit with a Breathable Fit for Summer
Size: 5, Color: Black
This 3-piece suit is a solid option for a summer wedding or any formal event where you want a kid to look sharp without them overheating. The linen material is high quality and feels much more breathable than a standard polyester suit. The jacket, vest, and pants all fit true to size and the stitching is clean throughout. I was impressed with how well the fabric holds its shape without getting excessively wrinkled after a few hours of wear. It’s a grounded, well-made formal set that balances a professional look with the comfort needed for a child to actually move around in it.
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Reviewed in the United States on March 17, 2026
★★★★★ 5
sharp Genetalman look for my Toddler
Size: 4, Color: Light Green, Size: 4, Color: Light Green
I was genuinely impressed with the quality of this 3-piece toddler linen suit. The stitching, structure, and overall tailoring give it a polished, high-end look. It doesn’t feel like a flimsy costume suit at all it actually looks like a properly tailored mini version of an adult formal outfit.
The green color is absolutely beautiful in person. It’s rich without being too loud and perfect for summer weddings, beach events, or formal family gatherings. The linen blend gives it that breathable, lightweight feel, which is ideal for warmer weather.
Now, sizing was completely my fault. I ordered a 4T for my 2-year-old (clearly wishful thinking 😅), so it runs bigger on him right now. But honestly, I’m not mad about it he’ll grow into it, and when he does, he’s going to look amazing. The slim-fit style gives it that modern, sharp look without being overly tight. It also has a working pockets which i thought was really cute
The jacket, vest, and pants together create such a classy appearance. I genuinely can’t wait for the next wedding invitation just so he can wear this.
Overall, excellent quality, beautiful color, and great craftsmanship. Easy 5 stars.
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Reviewed in the United States on February 18, 2026
★★★★★ 5
Summer wedding kids suit
Color: Navy, Size: 10 Years, Color: Navy, Size: 10 Years
Bought this suit for my son in the 10 youth size and honestly was pleasantly surprised by the quality for the price. The navy color looks sharp and dressy without being too stiff or uncomfortable. The material has a little stretch, which helped it fit nicely and made it comfortable for him to move around in.
The adjustable waist was a huge plus, especially for growing kids. It fit true to size overall, though the blazer sleeves were slightly long on my son. The pants had a nice slim look without being too tight. We paired it with white sneakers for a more modern look and it came out adorable.
This would be perfect for weddings, graduations, concerts, communion, school events, or family photos. Overall, very happy with the purchase and would definitely buy again.
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Reviewed in the United States on May 18, 2026
★★★★★ 5
Very Modern Handsome Suit
Color: Grey, Size: 7 Years, Color: Grey, Size: 7 Years
This is an incredibly sharp looking suit for the little guy. Great price and features, too. I made a mistake in sizing up instead of down and first one was too sloppy on him and would need alterations. He is thin and very thin in the waist. There is a lot of adjustment with buttons in waistband and coat hides the bunching. This shirt and coat will easily take a fuller body than slim I believe. He loves posing in it and feels very classy. Best purchase for a formal suit that will last longer than most kids clothes size wise. Felt bad about returning but careful folding and packing got it good as new.
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Reviewed in the United States on May 20, 2026
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