Radiator Hoses - Both

This procedure covers the removal and replacement of both the upper and lower radiator hoses on the 5.9L Cummins diesel engine, including proper coolant drainage and refilling.

Warnings

Tools required

Parts

• Upper radiator hose × 1 — Mopar 52079835 or equivalent
• Lower radiator hose × 1 — Mopar 52079836 or equivalent
• Hose clamps (stainless steel worm-gear type) × 4 — Use OEM specification
• Coolant/antifreeze × 4 — Use correct HOAT or conventional as specified

Fluids

• Ethylene glycol 50/50 (green conventional early, HOAT later) — 4 qt

Preparation

1. Ensure the engine is completely cold before beginning work
2. Park the vehicle on level ground and engage the parking brake
3. Place a drain pan with at least 5 gallon capacity under the radiator drain petcock
4. Remove the radiator cap slowly to release any residual pressure
5. Inspect the radiator, water pump, and thermostat housing connections for signs of leaks or corrosion while you have access

Procedure

1. 1

   Drain the cooling system
   Locate the drain petcock on the lower corner of the radiator (verify side against your specific vehicle). Open the petcock by turning counterclockwise and allow coolant to drain completely into the drain pan. If the petcock is seized or leaking, remove it completely and drain through the opening. On Cummins engines, the system holds approximately 22-24 quarts, so ensure adequate drain pan capacity.
   Torque spec

   Drain Petcock7 Nm (5 lb-ft)
2. 2

   Remove upper radiator hose from radiator
   Locate the upper radiator hose connected to the upper radiator tank (verify side against your specific vehicle). Using a flathead screwdriver or hose clamp pliers, loosen the hose clamp at the radiator end by turning the screw counterclockwise. Slide the clamp back along the hose away from the radiator connection. Twist and pull the hose off the radiator neck. If the hose is stuck, carefully insert a flathead screwdriver between the hose and neck to break the seal.
3. 3

   Remove upper radiator hose from thermostat housing
   Follow the upper radiator hose to the thermostat housing on the front driver's side of the engine block. Loosen the hose clamp using the same method as the radiator end. Twist and pull the hose off the thermostat housing outlet. Remove the upper hose completely from the vehicle.
4. 4

   Remove lower radiator hose from radiator
   Access the lower radiator hose connection at the driver's side lower radiator tank. This may require reaching from underneath or above depending on clearance with the A/C compressor and other components. Loosen the hose clamp and slide it back along the hose. Twist and pull the hose off the radiator neck. Note the routing of the hose for installation of the new hose.
5. 5

   Remove lower radiator hose from water pump
   Follow the lower radiator hose to the water pump/lower coolant inlet on the front of the engine (verify connection point on your specific engine). Loosen the hose clamp at the water pump connection. Twist and pull the hose off the water pump inlet. Remove the lower hose completely from the vehicle. Inspect the water pump inlet for corrosion or damage.
6. 6

   Clean all hose connections
   Using a shop rag or wire brush, thoroughly clean the radiator necks, thermostat housing outlet, and water pump inlet where the hoses connect. Remove all old coolant residue, corrosion, and gasket material. Inspect each connection for cracks, pitting, or damage. Any damaged connections should be addressed before installing new hoses.
7. 7

   Install new lower radiator hose to water pump
   Position a new hose clamp on the water pump end of the new lower radiator hose. Slide the hose onto the water pump inlet, ensuring it seats fully against the stop on the inlet neck. Position the clamp 1/4 inch from the end of the hose and tighten the worm-gear clamp until snug and secure (typically until the hose material just begins to bulge slightly at the clamp); do not overtighten.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
8. 8

   Install new lower radiator hose to radiator
   Route the lower radiator hose to the radiator following the same path as the original hose. Position a new hose clamp on the radiator end of the hose. Slide the hose onto the lower radiator neck, ensuring it seats fully. Position the clamp 1/4 inch from the end of the hose and tighten the worm-gear clamp until snug and secure; do not overtighten.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
9. 9

   Install new upper radiator hose to thermostat housing
   Position a new hose clamp on the thermostat housing end of the new upper radiator hose. Slide the hose onto the thermostat housing outlet, ensuring it seats fully against the stop. Position the clamp 1/4 inch from the end of the hose and tighten the worm-gear clamp until snug and secure; do not overtighten.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
10. 10

    Install new upper radiator hose to radiator
    Route the upper radiator hose to the radiator. Position a new hose clamp on the radiator end of the hose. Slide the hose onto the upper radiator neck, ensuring it seats fully. Position the clamp 1/4 inch from the end of the hose and tighten the worm-gear clamp until snug and secure; do not overtighten. Ensure the hose does not contact any sharp edges, the fan, or hot engine components.
    Torque spec

    Hose Clamps3 Nm (2 lb-ft)
11. 11

    Close drain petcock and refill cooling system
    Close the radiator drain petcock by turning clockwise and tighten to specification (hand tight). Using a funnel, slowly pour a 50/50 mixture of the correct coolant type into the radiator until it reaches the base of the filler neck. Pause periodically to allow air pockets to escape. Leave the radiator cap off for the next step.
    Torque spec

    Drain Petcock7 Nm (5 lb-ft)
12. 12

    Burp the cooling system
    With the radiator cap still off, start the engine and let it idle. Continue adding coolant as the level drops due to air purging from the system. The Cummins diesel may take several minutes to reach operating temperature and open the thermostat. Watch for coolant circulation in the radiator and monitor the temperature gauge. Once the thermostat opens and coolant circulates, top off the radiator to the base of the filler neck.
13. 13

    Install radiator cap and check reservoir
    Once the system is fully burped and at operating temperature, shut off the engine and allow it to cool slightly. Install the radiator cap by pressing down and turning clockwise until it locks. Check the coolant overflow reservoir and fill to the FULL COLD mark with the same 50/50 coolant mixture. The system will draw from the reservoir as it cools.

Reassembly

1. Double-check that all four hose clamps are tightened to specification and properly positioned
2. Verify that all hoses are routed correctly and do not contact moving parts like the fan or serpentine belt
3. Ensure the radiator cap is fully seated and locked in place
4. Clean up any spilled coolant from engine components and frame members

Verification

• Start the engine and let it reach full operating temperature while monitoring for leaks at all four hose connections
• Check that the heater produces hot air, confirming proper coolant circulation
• Verify the temperature gauge reads in the normal range (approximately 180-200°F)
• After the engine cools completely, recheck the coolant level in both the radiator and overflow reservoir, topping off as necessary
• Test drive the vehicle and monitor the temperature gauge under load to ensure proper cooling system operation
• Recheck all hose connections for leaks after the first drive cycle and inspect again after 100 miles

Related trouble codes on this vehicle

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