★★★★★ 5
Works as it should
Works as it should
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on March 24, 2026
Mishimoto 2017+ GMC 6.6L Duramax L5P Transmission Thermal Bypass Valve Kit
Marsoni
M251S
Get it in 3 business days with 1 day shipping.
Friday, May 29
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
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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.
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4.5 ★★★★★
Based on 512 reviews
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Product Reviews
★★★★★ 4
Four Stars
Just what I needed
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on October 14, 2016
★★★★★ 5
Functioned as advertized.
Installed these in my Whalers 96 200 Offshore. No issues, used permatex gasket compound on aluminum engine parts after cleaning with fine brass wire wheel.
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Reviewed in the United States on November 20, 2024
★★★★★ 5
Fits 1988 Sea Ray V-135 2 stroke (Mercury)
For those of you with the 135 hp
mercury that was branded as the "Sea Ray 135" and paint matched to the boat (i.e. Seville's and some others) this is the 147 degree thermostat for that motor. My Seville is an '88 and It's difficult to cross reference the serial numbers on those motors when searching for parts. Only buy Quicksilver parts for these motors. Happy to find them on Amazon because Boats.net as an example, is not clear on what you're getting.
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Reviewed in the United States on August 3, 2024
★★★★★ 5
fixed issue
stopped the overheat issue on my outboard!!!
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Reviewed in the United States on August 6, 2025
