Heater Hoses

Replace heater hoses on the 2008 Dodge Viper 8.4L V10, including inlet and outlet hoses between the engine and firewall heater core connections.

Warnings

Tools required

Parts

• Heater inlet hose × 1 — Use OEM specification
• Heater outlet hose × 1 — Use OEM specification
• Hose clamps (worm-gear type) × 4 — Replace if corroded

Fluids

• Mopar HOAT coolant 50/50 — 2 qt

Preparation

1. Ensure the engine is completely cold to the touch
2. Park the vehicle on level ground and engage the parking brake
3. Place a fender cover over the driver's side fender to protect the paint during work
4. Locate the coolant drain petcock on the driver's side lower radiator tank or remove the lower radiator hose to drain the system
5. Position a large drain pan beneath the radiator drain location

Procedure

1. 1

   Drain cooling system
   Remove the radiator cap slowly to release any residual pressure. Open the radiator drain petcock (located on the lower driver's side of the radiator) or carefully loosen the lower radiator hose clamp and slide the hose off to drain coolant into the drain pan. Drain at least 3-4 quarts to bring the coolant level below the heater core connections. If coolant is clean and within the past 2 years, it can be reused; otherwise, dispose of it properly and use fresh coolant.
2. 2

   Locate heater hose connections
   Open the hood and identify the heater hoses at the firewall on the passenger side of the engine bay. The two heater hoses connect from the engine's coolant circuit to the heater core inlet and outlet tubes that protrude through the firewall. Verify the exact engine-side connection points against the 2008 Viper service manual, as the V10's coolant routing differs from typical V8/inline layouts. The inlet hose is typically the lower of the two connections and may have a larger diameter. Note the routing of both hoses and any support brackets or clips.
3. 3

   Remove air intake components if necessary
   Depending on access requirements, you may need to remove the air intake tube or airbox assembly to reach the heater hose connections at the engine. Loosen the hose clamp at the throttle body, disconnect any air intake electrical connectors (e.g., intake air temperature sensor) as needed, and remove fasteners securing the airbox. Set components aside in a clean area.
4. 4

   Disconnect heater inlet hose at firewall
   Using hose clamp pliers or a flat-blade screwdriver, loosen the hose clamp securing the heater inlet hose to the heater core tube at the firewall. Slide the clamp back along the hose away from the connection point. Twist the hose gently to break it free from the heater core tube, then pull it straight off. Expect residual coolant to drain; have shop towels ready.
5. 5

   Disconnect heater inlet hose at engine
   Follow the heater inlet hose to its connection point at the engine (typically at the water pump housing or a coolant pipe on the driver's side of the engine). Loosen the hose clamp, slide it back, twist the hose to break the seal, and remove the hose from the engine fitting. Remove the old hose completely from the vehicle.
6. 6

   Disconnect heater outlet hose at firewall
   Repeat the disconnection process for the heater outlet hose at the firewall heater core tube connection. Loosen the hose clamp, slide it back, twist and pull the hose off. Have towels ready for residual coolant spillage.
7. 7

   Disconnect heater outlet hose at engine
   Trace the heater outlet hose to its engine connection point (typically at the thermostat housing or cylinder head coolant outlet on the passenger side). Loosen the clamp, slide it back, twist and remove the hose. Remove the old heater outlet hose completely from the vehicle. Inspect both heater core tubes at the firewall for corrosion, damage, or cracking.
8. 8

   Inspect and clean connection points
   Inspect all four hose connection points (two at firewall heater core tubes, two at engine fittings) for corrosion, scale buildup, or damage. Clean the connection surfaces with a rag to remove old coolant residue and ensure a proper seal for the new hoses. Check that heater core tubes are not loose in the firewall; they should be firmly mounted.
9. 9

   Install new heater inlet hose
   Route the new heater inlet hose from the engine connection point to the firewall heater core tube, following the original path and avoiding sharp bends or contact with hot exhaust components. Slide new hose clamps onto both ends of the hose before making connections. Push the hose firmly onto the engine fitting first, then onto the firewall heater core tube. Ensure each end is fully seated (typically 1.5-2 inches onto the fitting). Position the hose clamps approximately 0.5 inch from the end of each hose and tighten securely with hose clamp pliers or screwdriver. Do not overtighten to the point of cutting into the hose.
10. 10

    Install new heater outlet hose
    Route the new heater outlet hose from the engine connection point to the firewall heater core tube, following the original path. Slide new hose clamps onto both ends. Push the hose firmly onto the engine fitting and the firewall heater core tube, ensuring full seating on both ends. Position and tighten the hose clamps approximately 0.5 inch from the end of each hose. Verify that neither hose contacts moving components, sharp edges, or hot exhaust manifolds.
11. 11

    Reinstall air intake components
    If air intake components were removed, reinstall them in reverse order. Secure the airbox with its fasteners, reconnect the mass airflow sensor electrical connector, and tighten the hose clamp at the throttle body connection. Ensure all connections are secure and no tools or rags are left in the engine bay.
12. 12

    Close drain and refill cooling system
    Close the radiator drain petcock or reconnect and clamp the lower radiator hose securely. Using a funnel, slowly pour Mopar HOAT 50/50 coolant mixture into the radiator filler neck until the level reaches the bottom of the filler neck. Note that this large-displacement V10 may require several quarts to refill the drained volume; have adequate coolant on hand. Add coolant slowly to allow air to escape. If the vehicle has a coolant overflow reservoir, fill it to the COLD FULL mark.
13. 13

    Bleed cooling system
    Start the engine with the radiator cap still off (have a rag ready in case of overflow). Allow the engine to idle and warm up to operating temperature while monitoring the coolant level. As the thermostat opens and coolant circulates, the level will drop; add more coolant as needed. Turn the heater control to maximum heat and fan speed to circulate coolant through the heater core. Watch for steady coolant flow in the radiator and feel the heater hoses to confirm they are both hot, indicating proper circulation. Once the engine reaches operating temperature and coolant level stabilizes, carefully install the radiator cap.
14. 14

    Check for leaks and test heater operation
    With the engine at operating temperature, visually inspect all four heater hose connections for coolant leaks. Check underneath the vehicle for any drips. Rev the engine to 2000-2500 RPM briefly while watching for leaks under pressure. Verify that the heater produces hot air inside the cabin. Shut off the engine and allow it to cool, then recheck the coolant level in the overflow reservoir and top off to the COLD FULL mark if needed.

Reassembly

1. Reinstall air intake components if removed, ensuring all electrical connectors are secured
2. Double-check that all hose clamps are tight and positioned correctly on each connection
3. Verify coolant level is at the COLD FULL mark on the overflow reservoir after the engine has cooled

Verification

• Start the engine and allow it to reach operating temperature; verify no coolant leaks at any of the four heater hose connections
• Confirm both heater hoses become hot to the touch, indicating proper coolant circulation through the heater core
• Test cabin heater operation at maximum heat setting to ensure hot air is produced
• After a cool-down period, recheck coolant level in the overflow reservoir and top off if necessary
• Take a short test drive and recheck for leaks after the vehicle has cooled

Related trouble codes on this vehicle

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