Product Overview
Fleece Performance Coolant Bypass Kit for 2003–2005 Dodge/Ram 5.9L Cummins Automatic Transmission
The Fleece Performance Coolant Bypass Kit is designed for compatible 2003–2005 Dodge/Ram 2500 and Ram 3500 trucks equipped with the 5.9L 24-valve Cummins diesel engine and automatic transmission.
The rear cylinders of the Cummins engine can receive less coolant flow than the front cylinders, which may contribute to higher localized coolant temperatures and increased cooling-system pressure near the rear of the engine block.
This coolant bypass kit adds a secondary, temperature-controlled coolant circuit that helps improve coolant circulation across all six cylinders. By improving coolant flow before excessive pressure develops, the system is designed to promote more consistent engine temperatures and improved long-term cooling-system reliability.
Key Benefits
- Improved Rear-Cylinder Coolant Flow: Adds an additional coolant path at the rear of the engine.
- Balanced Cooling: Designed to help maintain more consistent coolant temperatures across all six cylinders.
- Temperature-Controlled Operation: Secondary thermostat opens according to coolant temperature rather than cooling-system pressure.
- Cooling-System Protection: Helps reduce localized pressure that can contribute to freeze-plug failures.
- Leak-Free Installation: Complete kit includes braided stainless-steel hose and AN O-ring fittings.
- Billet Hose Brackets: Includes billet mounting brackets for clean hose routing.
How the Coolant Bypass Works
The factory cooling system routes coolant from the front of the engine toward the rear, allowing the rear cylinders to experience higher coolant temperatures under heavy engine loads.
The Fleece Performance Coolant Bypass introduces a secondary coolant path equipped with its own thermostat. As coolant temperature rises, the thermostat opens and allows additional coolant to circulate from the rear of the cylinder head back into the cooling system.
Unlike pressure-operated bypass systems, the Fleece design responds directly to coolant temperature, helping improve coolant distribution before excessive pressure develops.
Cooling-System Protection
Improving coolant circulation at the rear cylinders helps reduce localized hot spots and excessive cooling-system pressure that may contribute to freeze-plug failures and other cooling-system concerns.
Actual cooling-system performance will vary depending on engine load, towing conditions, ambient temperatures, cooling-system condition, installation quality, maintenance, and other vehicle modifications.
Application Notes
This version is specifically designed for 2003–2005 Dodge/Ram trucks equipped with the 5.9L 24-valve Cummins diesel engine and automatic transmission.
Installation removes the factory transmission-fluid heat exchanger. The heat exchanger is intended to warm transmission fluid using engine coolant during cold-weather operation. Removal is commonly accepted for warm climates and high-performance applications, but owners operating in colder environments should consider transmission warm-up requirements.
- Transmission: Automatic transmission only
- Heat Exchanger: Factory transmission-fluid heat exchanger is removed during installation
- Climate Consideration: Evaluate cold-weather operation before removing the factory heat exchanger
- Model Years: 2003–2005
- Engine: 5.9L 24-Valve Cummins Diesel
Coolant-Flow Comparison
Without Coolant Bypass
With Fleece Performance Coolant Bypass
Product Specifications
- Product Type: Coolant Bypass Kit
- Application: 2003–2005 Dodge/Ram 2500 & Ram 3500
- Engine: 5.9L 24-Valve Cummins Diesel
- Transmission: Automatic Transmission Only
- Bypass Operation: Temperature-Controlled Secondary Thermostat
- Hose Type: Braided Stainless-Steel Coolant Hose
- Fitting Type: AN O-Ring Fittings
- Mounting Brackets: Billet Aluminum Hose Brackets Included
- UPC: 670875715059
- Shipping Weight: 10 lbs
Certification
CARB Executive Order: D-834-9
Warranty
Installation Resources
Trademark Information
Protected under U.S. Trademark Registration Nos. 6,099,979; 6,099,980; 6,099,981; and 7,659,022.
California Proposition 65 Warning
WARNING: Cancer and Reproductive Harm — P65Warnings.ca.gov
Disclaimer
Verify fitment before ordering. Emissions, warranty, installation requirements, and local regulations may vary by vehicle and location. This coolant bypass kit is intended for compatible 2003–2005 Dodge/Ram 5.9L Cummins automatic-transmission applications and removes the factory transmission-fluid heat exchanger during installation.
Vehicle Fitment
| Year | Make | Model | Engine | Transmission |
|---|---|---|---|---|
| 2003–2005 | Dodge/Ram | Ram 2500 | 5.9L 24-Valve Cummins | Automatic |
| 2003–2005 | Dodge/Ram | Ram 3500 | 5.9L 24-Valve Cummins | Automatic |
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