Radiator Hose - Lower

This procedure covers the removal and replacement of the lower radiator hose on a 2007 Ram 3500 with the 5.9L Cummins diesel engine.

Warnings

Tools required

Parts

• Lower radiator hose × 1 — Use OEM specification
• Hose clamps (2) × 2 — Use OEM worm-gear style or replace with existing if reusable

Fluids

• HOAT coolant 50/50 — 4 qt

Preparation

1. Ensure engine is completely cold before beginning work
2. Park vehicle on level ground and engage parking brake
3. Place drain pan under the front of the vehicle below the radiator
4. Remove the radiator cap slowly to relieve any residual pressure in the cooling system

Procedure

1. 1

   Drain coolant from radiator
   Open the radiator petcock valve located at the bottom driver side of the radiator by turning counterclockwise, or remove the lower radiator hose to drain. Allow coolant to drain completely into the drain pan. If coolant is clean and less than 3 years old, it can be reused; otherwise dispose of properly and use fresh coolant.
2. 2

   Access lower radiator hose connections
   The lower radiator hose connects to the bottom of the radiator and runs to the water pump inlet on the front of the engine block. Identify both connection points visually on your vehicle and ensure you have adequate working room. Identify both connection points and ensure you have adequate working room. You may need to reach from above or below depending on installed accessories.
3. 3

   Remove radiator-side hose clamp
   Locate the hose clamp securing the lower hose to the radiator outlet. Using a flat blade screwdriver or hose clamp pliers, loosen the worm-gear clamp by turning counterclockwise. Slide the clamp back along the hose away from the radiator connection point at least 2-3 inches.
4. 4

   Remove engine-side hose clamp
   Locate the hose clamp at the water pump connection on the engine block. Loosen this clamp in the same manner as the radiator side and slide it back along the hose. Be prepared for residual coolant to drain when the hose is removed.
5. 5

   Remove lower radiator hose
   Twist the hose back and forth while pulling to break the seal at both connections. The hose may be stuck due to age and heat cycling. If necessary, carefully use a flat blade screwdriver to gently pry between the hose and fitting, being careful not to damage the radiator or water pump outlets. Remove the hose and allow any remaining coolant to drain into the pan.
6. 6

   Clean connection surfaces
   Thoroughly clean both the radiator outlet and water pump inlet using shop towels. Remove any old rubber residue, corrosion, or debris. Inspect both metal fittings for damage, cracks, or excessive corrosion. Replace components if damage is found.
7. 7

   Install new lower radiator hose
   Position the new hose clamps on the new lower radiator hose before installation. Slide the hose onto the water pump inlet first, pushing it fully onto the fitting until it seats against the stop bead. Then route the hose to the radiator outlet and push it fully onto the radiator connection.
8. 8

   Secure hose clamps
   Position the hose clamps approximately 1/2 inch from the end of each hose connection. Tighten both clamps firmly using a screwdriver or hose clamp pliers. Clamps should be snug enough to prevent leaks but not so tight that they cut into the hose material. Ensure clamp screws are positioned for future access.
9. 9

   Close radiator drain and refill system
   Close the radiator petcock valve by turning clockwise until snug (hand tight only). Using a funnel, slowly pour coolant mixture into the radiator until full. Fill the coolant overflow reservoir to the FULL COLD mark. Verify total cooling system capacity against the factory service manual for your vehicle; you will need approximately 3-4 quarts to replace what was drained from the radiator alone.
10. 10

    Bleed air from cooling system
    With the radiator cap off, start the engine and allow it to idle. Turn the heater to maximum heat and fan on. As the engine warms, watch the coolant level and add coolant as needed as air purges from the system. When the thermostat opens (verify opening temperature against OEM spec, typically around 180-190°F), coolant will circulate and the level will drop. Continue adding coolant until level stabilizes and no more air bubbles emerge.
11. 11

    Final coolant fill and cap installation
    Once the engine reaches operating temperature and air is purged, top off the radiator to the base of the filler neck. Install the radiator cap securely. Check the overflow reservoir level and adjust to the FULL HOT mark if needed. Allow engine to idle for 2-3 more minutes.

Reassembly

1. Double-check that both hose clamps are tight and properly positioned
2. Verify the radiator cap is installed securely
3. Wipe down all surfaces to remove coolant residue for easier leak detection

Verification

• With engine at operating temperature, visually inspect both hose connections for any signs of coolant leakage
• Check coolant level in overflow reservoir after engine cools - should be at FULL COLD mark
• Squeeze the upper radiator hose to verify it becomes firm when hot, indicating proper system pressure
• Monitor coolant level and temperature gauge during the first few drives to ensure system is functioning properly
• Re-check hose clamps after the first heat cycle and tighten if necessary

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