SKU: 56458609582

Fleece Performance FPE-CLNTBYPS-CUMMINS-MAN Cummins Coolant Bypass Kit 2003-2007 Manual Transmission Fleece Performance

Sale price$245.70 Regular price$273.00
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Ships within 48 hours · Estimated delivery Jul 12 - Jul 17

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Description

Fleece Performance FPE-CLNTBYPS-CUMMINS-MAN Cummins Coolant Bypass Kit 2003-2007 Manual Transmission Fleece PerformanceIncreased Coolant Flow, Decreased Coolant Temperatures, The rear cylinders on the 5. 9 6. 7L Cummins suffer from a lack of coolant flow, and therefore, experience the highest coolant temperatures. This can cause excessive pressure to build in the cooling system, especially the rear of the block and blow out freeze plugs externally, or the smaller diameter plugs under the valve cover, leading to a failure. Our coolant bypass kit adds a secondary

Increased Coolant Flow, Decreased Coolant Temperatures, The rear cylinders on the 5.9/6.7L Cummins suffer from a lack of coolant flow, and therefore, experience the highest coolant temperatures.

This can cause excessive pressure to build in the cooling system, especially the rear of the block and blow out freeze plugs externally, or the smaller diameter plugs under the valve cover, leading to a failure.

Our coolant bypass kit adds a secondary thermostat, that unlike other brands, works based on temperature instead of excessive pressure. This solves the problem before pressure becomes an issue by ensuring consistent temperatures across all six cylinders.
Benefits:

  • Lowers coolant temperature at the rear cylinders
  • Ensures consistent temperatures across all cylinders
  • Prevents damaging coolant pressure build up
  • Complete kit comes with braided hose and AN O-ring fittings to ensure a leak-free installation.
  • Kits for MY 2003 and up include billet hose brackets.

Why do I need a Fleece Coolant Bypass?

One of the biggest issues on the 5.9/6.7L Cummins is the coolant flow problem to the rear cylinders. This can cause catastrophic failure or blow outs of the freeze plugs in an over-temperature / over-pressure condition. The Fleece Coolant Bypass is one of the most important additions you make to improve the reliability and longevity of the Cummins platform.

The 03-07 5.9L automatic transmission version will eliminate the factory transmission fluid heat exchanger. The heat exchanger is not a fluid cooler; it was designed for use in cold climates to warm the transmission fluid with the engine coolant.

It is not necessary for use in warm climates or high horsepower applications, nor does it detrimentally affect the trucks performance when removed. All 07-13 6.7 trucks, both automatic and manual equipped transmissions, do not have a transmission fluid heat exchanger.

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]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 56458609582

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Christy F
Bozeman, US
★★★★★ 5
Great socks
Size: Medium, Color: Pink - 647
Well-made and comfortable to wear. Great for golf and other outdoor activities. Like them because they do not show above shoes.
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Reviewed in the United States on April 19, 2026
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Cait E
Lexington, US
★★★★★ 5
These ACTUALLY stay put all day long - I was skeptical, but am so glad I took a chance on these
Size: Medium, Color: (014) Halo Gray / Halo Gray / Castlerock
I was so skeptical about whether these would stay on my feet all day without sliding down into my shoe - I’ve tried so many socks in the past with the silicone strip on the heel which failed. I’ve owned these for a couple months now and they have never slipped down - they stay put all day! I love the variety of colors to choose from, and the value per pack is great since six pairs come per pack (I thought it was only three when I first purchased and was pleasantly surprised by the additional pairs). They also have perfect thickness - not too warm to wear during the summer months with sneakers; I live in a tropical climate, though, so I’m not sure how they will do in cooler climates. I’ve washed each pair once or twice and the color and quality of the silicone has stayed so far (knock on wood). Overall: high recommend based on my experience so far!
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Reviewed in the United States on September 13, 2025
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Maggie Vega
Waukegan, US
★★★★★ 5
Great fit!
Size: Medium, Color: (403) Washed Navy / Washed Navy / Blue Smoke
Great quality!
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Reviewed in the United States on May 15, 2026
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Theresa
Los Angeles, US
★★★★★ 4
No show but stays on
Size: Medium, Color: (014) Halo Gray / Halo Gray / Castlerock
I wear these socks daily. They truly don’t show with my workout shoes or with hey dudes. But the best thing about them is that they actually stay on your foot. I work out hard and I don’t ever have to pull them up. I do wish they were just a little bit thicker than they are, but they are definitely a product I will buy again.
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Reviewed in the United States on May 22, 2026
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Kira Stewart
Charlottesville, US
★★★★★ 5
My favorite socks
Size: Medium, Color: (659) Fuchsia Dusk / Fuchsia Dusk / Tourmaline Pink
Very comfortable. True to size. Moisture wicking
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Reviewed in the United States on April 25, 2026

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