This procedure covers the removal and replacement of heater hoses on the 2012-2018 Jeep Wrangler 3.6L V6, including coolant drainage, hose removal, and system refill.

Warnings

Tools required

Parts

• Heater inlet hose × 1 — Use OEM specification
• Heater outlet hose × 1 — Use OEM specification
• Hose clamps (spring or worm gear type) × 4 — Use OEM specification
• Mopar OAT Coolant (Purple) × 1 — 68048953AC or equivalent

Fluids

• Mopar OAT Coolant (Purple) — 2 qt

Preparation

1. Ensure engine is completely cold to the touch (minimum 2 hours after last operation)
2. Park vehicle on level ground and engage parking brake
3. Place drain pan under radiator drain petcock on passenger side of radiator
4. Remove coolant reservoir cap slowly to release any residual pressure
5. Locate heater hoses at firewall on passenger side of engine bay and at engine connections

Procedure

1. 1

   Drain coolant from system
   Open the radiator drain petcock located at the bottom passenger side of the radiator by turning counterclockwise. Allow coolant to drain into pan until flow stops. For better drainage, you may also drain from the engine block drain plug if accessible. Collect drained coolant in appropriate container for recycling.
   Torque spec

   Drain Petcock8 Nm (6 lb-ft)
2. 2

   Access heater hose connections at firewall
   Locate the two heater hoses passing through the firewall on the passenger side of the engine compartment. These hoses connect to the heater core inside the vehicle. Note the routing and positions of inlet (typically upper) and outlet (typically lower) hoses for correct reinstallation.
   ℹ️Take a photo of hose routing before removal to ensure correct installation path and avoid kinks or interference.
3. 3

   Remove hose clamps at firewall connections
   Using hose clamp pliers or flathead screwdriver, release the hose clamps at the firewall connections. If using spring-type clamps, compress and slide away from connection point. If using worm-gear clamps, loosen screw and slide clamp down the hose. Place clamps aside if reusing, or discard if replacing.
4. 4

   Disconnect hoses from firewall fittings
   Twist heater hoses gently while pulling to break them free from the heater core tubes at the firewall. If hoses are stuck due to age, carefully use a utility knife to slice the old hose lengthwise (being careful not to damage the metal tubes) and peel away. Expect residual coolant to drain from hoses.
   ⚠Do not pry or use excessive force on firewall heater core tubes as they can bend or break, requiring expensive heater core replacement.
5. 5

   Access engine-side heater hose connections
   Trace heater hoses from firewall to engine connections. The inlet hose connects near the thermostat housing on the front of the engine. The outlet hose typically connects to the engine block or water pump area on the passenger side. Clear any components or wiring that may obstruct access.
6. 6

   Remove hose clamps at engine connections
   Release the hose clamps at the engine-side connections using the same method as at the firewall. Note the orientation and type of clamps for reinstallation. Slide clamps well away from the connection points.
7. 7

   Remove heater hoses from engine
   Twist and pull heater hoses from engine connections. Remove both inlet and outlet hoses completely from the vehicle, noting their routing path through the engine bay. Inspect metal connection tubes at both engine and firewall for corrosion, damage, or sharp edges that could damage new hoses.
8. 8

   Prepare and install new heater hoses
   Clean all connection points at engine and firewall with shop towels. Remove any old gasket material or corrosion. Route new heater hoses along the same path as originals, ensuring proper length and avoiding sharp bends, hot exhaust components, or moving parts. Connect inlet hose first (to thermostat housing area), then outlet hose.
   ℹ️Ensure hoses are pushed fully onto connection tubes until they bottom out. Insufficient insertion will cause coolant leaks.
9. 9

   Install and tighten hose clamps
   Position hose clamps approximately 1/4 inch from the end of each hose on all four connections (two at firewall, two at engine). Ensure clamps are beyond the bead or ridge on the connection tubes. Tighten worm-gear type clamps to specified torque, or ensure spring clamps are fully seated in their grooves.
   ⚠Do not overtighten hose clamps as this can cut into hoses and cause premature failure. Use torque wrench for worm-gear clamps.
   Torque spec

   Hose Clamps4 Nm (3 lb-ft)
10. 10

    Close drain petcock and refill cooling system
    Close the radiator drain petcock by turning clockwise hand-tight to specified torque. Fill cooling system through coolant reservoir with Mopar OAT purple coolant mixed 50/50 with distilled water (or use pre-mixed coolant). Fill until level reaches the MAX cold fill line on reservoir. Do not overfill.
    Torque spec

    Drain Petcock8 Nm (6 lb-ft)
11. 11

    Bleed air from cooling system
    With reservoir cap off, start engine and allow to idle. Turn heater controls to maximum heat and fan on low. Watch coolant level in reservoir and add coolant as level drops during air purging. Gently squeeze upper radiator hose several times to help release air pockets. Continue until engine reaches operating temperature and thermostat opens (upper radiator hose becomes hot).
    ⚠Monitor temperature gauge closely. If gauge approaches red zone or overheating occurs, shut off engine immediately and allow to cool before continuing.
12. 12

    Final coolant level check and system test
    Once engine is at operating temperature and cooling fan has cycled on at least once, turn off engine and allow to cool for 15 minutes. Recheck coolant level in reservoir and top off to MAX cold line if needed. Install reservoir cap securely. Inspect all heater hose connections for leaks.

Reassembly

1. Ensure all hose clamps are properly tightened to specification and positioned correctly
2. Verify heater hoses are not kinked, touching hot exhaust components, or rubbing against sharp edges
3. Confirm coolant reservoir is filled to MAX cold line and cap is installed securely
4. Wipe down engine bay to remove any coolant spills that could attract dirt or cause odors

Verification

• Start engine and verify heater produces hot air when climate controls are set to maximum heat
• Check for coolant leaks at all four hose connections (two at firewall, two at engine) while engine is at operating temperature
• Verify temperature gauge remains in normal operating range and cooling fan cycles properly
• Recheck coolant level after first drive cycle (when engine is cold) and top off if necessary
• Monitor coolant level over the next few days and add as needed if air pockets continue to purge from system

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