Description
Solve the 5.9L Cummins' uneven cooling problem with the iFJF Coolant Bypass Kit. The factory cooling system on 2003-2007 Dodge Ram Cummins engines suffers from poor coolant circulation at the rear cylinders (cylinders 5 and 6), which run significantly hotter than the front cylinders. This temperature imbalance leads to premature wear, reduced performance, and potential head gasket issues. Our bypass kit redirects coolant flow to ensure consistent temperatures across all six cylinders, extending engine life and improving overall reliability.
Key Features & Benefits
-
Lower Rear Cylinder Temperatures: Actively reduces coolant temperature at cylinders 5 and 6 by up to 30°F, eliminating the factory hot-spot that accelerates engine wear.
-
High-Quality Aluminum Construction: CNC-machined from billet aluminum with a corrosion-resistant finish — built to handle diesel coolant chemistry and vibration.
-
Metal & Polyester-Reinforced Hoses: Durable hoses designed to withstand high coolant temperatures and pressures without ballooning or cracking.
-
Even Cooling Across All Cylinders: Ensures consistent temperature distribution, reducing thermal stress on the head gasket and cylinder head.
-
Extended Engine Life: Even cooling means less thermal cycling stress, longer head gasket life, and more miles between rebuilds.
-
Complete Bolt-On Kit: Includes all hoses, fittings, clamps, and mounting hardware. No cutting or permanent modification required.
Vehicle Compatibility
| Year |
Make |
Model |
Engine |
Notes |
| 2003-2007 |
Dodge |
Ram 2500 |
5.9L Cummins ISB |
Direct Fit |
| 2003-2007 |
Dodge |
Ram 3500 |
5.9L Cummins ISB |
Direct Fit |
Technical Specifications
| Material |
Billet Aluminum + Metal/Polyester Hoses |
| Kit Type |
Coolant Bypass Kit (Complete) |
| Temperature Reduction |
Up to 30°F at Rear Cylinders |
| Installation |
Bolt-On (No Cutting Required) |
| Installation Time |
2-3 Hours |
Installation Guide
Installation is straightforward with basic hand tools. The kit mounts at the rear of the cylinder head near the heater core connections. Drain a portion of the coolant, install the bypass fittings at the specified locations, route the hoses, and secure with the provided clamps. Refill and bleed the cooling system. A coolant flush is recommended before installation for optimal results. Estimated DIY time: 2-3 hours.
Frequently Asked Questions
Q: Why do the rear cylinders run hotter on a 5.9L Cummins?
A: The factory cooling system design sends coolant from the water pump through the front of the block first. By the time coolant reaches cylinders 5 and 6 at the rear, it has already absorbed significant heat. The bypass kit provides a secondary coolant path to the rear, equalizing temperatures.
Q: Will this fix my head gasket issues?
A: While it won't fix an already-blown head gasket, installing this bypass kit can help prevent future head gasket failures by reducing thermal stress from uneven cylinder temperatures. Combine it with ARP head studs for maximum protection.
Q: Is this compatible with a coolant filtration system?
A: Yes! This bypass kit works alongside coolant filtration systems. In fact, using both together provides the best protection — filtered coolant with even temperature distribution.
Related Products
