SKU: 64976363296

Fleece Performance FPE-CLNTBYPS-CUMMINS-0305 Cummins Coolant Bypass Kit 2003-2005 Auto Trans Fleece Performance

Sale price$245.70 Regular price$273.00
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Description

Fleece Performance FPE-CLNTBYPS-CUMMINS-0305 Cummins Coolant Bypass Kit 2003-2005 Auto Trans 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+ 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
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Exchange/Return Notes
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  • 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: 64976363296

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Maria White
Houston, US
★★★★★ 5
Perfect!
Number of Items: 3, Color: Pink Quartz Assorted (3-pairs), Size: Medium
My new favorite socks! True to size, fit perfectly, and the best part is they do not slide off your foot! 10/10 recommend!
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Reviewed in the United States on July 10, 2025
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Amazon Customer
Port Orchard, US
★★★★★ 5
The perfect sock!
Size: 6-10, Color: Halo Gray/Assorted
The only socks that I can wear with my hey dudes. They stay on my ankles and never slid down into the shoe. I will forever order these as long as they are available. They are comfy too!
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Reviewed in the United States on August 21, 2025
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Ryan S
Dallas, US
★★★★★ 5
Good option, especially in warmer weather
Size: 6-10, Color: Black
High quality socks and very durable. Nice touch adding the grip on the back of the ankle so the sock stays up. Size is a true fit to the size of your foot as well.
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Reviewed in the United States on April 17, 2025
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Patricia
Cuba, US
★★★★★ 5
Love these socks!
Size: 6-10, Color: White
Comfortable, no show, and most importantly The Do No Slip!!!! I keep coming back to add to my supply because they have become the only sock I wear. I’ve been using them for a couple years now and they hold to great to washing, bleaching and the dryer. Highly recommended.
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Reviewed in the United States on July 24, 2024
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BoyMom
Chelsea, US
★★★★★ 5
The only socks I will buy
Size: 6-10, Color: Halo Gray/Assorted
These are hands down my favorite socks to wear with tennis shoes. Bought my original 6 pack in the store, liked them so much I went buy more and they were gone. These don't slip on your heel like most socks do. Come up high enough on the top of your foot to protect from tongue rubbing (I giggled when I wrote that) and they come in fun colors. Love they are ultra no show and provide padding but people can't see them with shoes on. Five stars!
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Reviewed in the United States on January 12, 2023

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