Replace heater hoses connecting the engine block to the heater core, ensuring proper coolant flow to the cabin heating system.

Warnings

Tools required

Parts

• Heater inlet hose × 1 — Use OEM specification
• Heater outlet hose × 1 — Use OEM specification
• Hose clamps (if reusing is not recommended) × 4 — Constant tension style

Fluids

• Mopar OAT Coolant (Purple) — 2 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level ground and engage parking brake
3. Place drain pan under radiator drain plug location
4. Remove engine cover by pulling upward on retaining clips
5. Remove air intake tube from air filter housing to turbo inlet for better access to passenger side of engine

Procedure

1. 1

   Drain cooling system
   Locate the radiator drain plug at the bottom passenger side of the radiator. Slowly open the drain plug and drain approximately 2-3 gallons of coolant into the drain pan. This reduces coolant loss and mess when disconnecting heater hoses. Close the drain plug once coolant level is below heater hose connections.
   Torque spec

   Coolant Drain Plug15 Nm (11 lb-ft)
2. 2

   Locate heater hoses
   Identify the two heater hoses on the passenger side of the engine block. The inlet hose (larger diameter, approximately 3/4 inch) connects from the engine block to the firewall. The outlet hose (smaller diameter, approximately 5/8 inch) returns from the firewall to the engine block or thermostat housing. Trace hoses to confirm routing before removal.
3. 3

   Remove inlet hose at engine block
   Using hose clamp pliers, compress and slide the clamp away from the connection point on the engine block. Twist the hose gently to break the seal, then pull firmly to remove from the fitting. If the hose is stuck, carefully use a razor blade to cut along the fitting (without scoring the metal) to aid removal. Allow residual coolant to drain into the pan.
   ⚠Old hoses may be adhered to fittings. Do not use excessive force that could damage the metal fitting on the engine block.
4. 4

   Remove inlet hose at firewall
   Access the firewall connection behind the engine. Compress the hose clamp and slide away from the fitting. Twist and pull the hose from the heater core inlet pipe at the firewall. This connection may be difficult to reach; use extensions or work from above and below as needed.
5. 5

   Remove outlet hose at firewall
   Locate the heater core outlet pipe at the firewall (typically lower than the inlet). Compress and slide the hose clamp, then twist and remove the hose from the firewall fitting. Note the routing path of the hose for proper installation of the new hose.
6. 6

   Remove outlet hose at engine
   Follow the outlet hose to its connection point at the engine, typically at the thermostat housing or engine block return fitting. Compress and slide the clamp, twist and pull to remove the hose. Remove both hoses completely from the vehicle.
7. 7

   Inspect fittings and clean connections
   Inspect all metal fittings on the engine block, thermostat housing, and firewall for corrosion, damage, or debris. Clean fittings with a shop towel. Check that fittings are not loose in the engine block or thermostat housing. If fittings have any play or leaks, they must be addressed before installing new hoses.
   ℹ️Damaged or corroded fittings will cause leaks even with new hoses. Inspect carefully before proceeding.
8. 8

   Install new inlet hose
   Route the new heater inlet hose from the engine block fitting to the firewall inlet pipe, following the original path. Ensure the hose is not kinked or touching hot exhaust components. Slide hose clamps onto the hose before making connections. Push the hose firmly onto the engine block fitting until it bottoms out, then position the clamp 1/4 inch from the hose end and tighten.
   Torque spec

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

   Connect inlet hose at firewall
   Push the inlet hose firmly onto the heater core inlet pipe at the firewall until fully seated. Position the hose clamp 1/4 inch from the hose end and tighten to specification. Verify the hose is fully seated on both ends by pulling firmly.
   Torque spec

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

    Install new outlet hose
    Route the new heater outlet hose from the firewall outlet pipe to the engine connection point (thermostat housing or block), following the original routing. Install hose clamps on the hose before connections. Push the hose onto the firewall fitting until fully seated, position the clamp, and tighten to specification.
    Torque spec

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

    Connect outlet hose at engine
    Push the outlet hose firmly onto the engine block or thermostat housing fitting until fully seated. Position the hose clamp 1/4 inch from the hose end and tighten to specification. Double-check all four hose clamps are properly tightened and positioned.
    Torque spec

    Hose Clamps3 Nm (2 lb-ft)
12. 12

    Refill cooling system
    Using a coolant funnel at the coolant expansion tank, slowly add Mopar OAT Purple coolant to bring the level to the COLD MAX line. Start the engine and allow it to idle with the heater on maximum heat. As the thermostat opens and air purges from the system, add additional coolant as needed. Run until the engine reaches normal operating temperature and both heater hoses are hot to the touch.
    ⚠The 6.7L Cummins may take 10-15 minutes to purge all air from the cooling system. Monitor coolant level continuously during this process.
13. 13

    Inspect for leaks
    With the engine at operating temperature, carefully inspect all four hose connections for coolant leaks. Look for seepage or drips at each clamp location. Check the drain plug for leaks. Wipe connections dry with a shop towel and recheck after 2-3 minutes of running. Tighten clamps an additional 1/4 turn if any seepage is observed.

Reassembly

1. Reinstall air intake tube and connect to turbo inlet and air filter housing
2. Reinstall engine cover by pressing firmly until all clips engage
3. Top off coolant expansion tank to COLD MAX line after system has fully cooled
4. Properly dispose of used coolant according to local environmental regulations

Verification

• Start engine and verify heater produces hot air within 5 minutes of reaching operating temperature
• Inspect all hose connections for leaks with engine at operating temperature
• Check coolant level after first drive cycle and top off if necessary
• Verify no coolant smell in cabin and no coolant puddles under vehicle after overnight parking
• Monitor temperature gauge during test drive to ensure engine maintains normal operating temperature

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