Radiator Hose - Lower

Replacement of the lower radiator hose on a 1970 AMC Rebel Machine with 390ci V8 engine, including coolant draining and refilling.

Warnings

Tools required

Parts

• Lower radiator hose × 1 — Use OEM specification or Gates 21543
• Hose clamps (worm gear type) × 2 — 1.5 to 2 inch diameter

Fluids

• Engine coolant (ethylene glycol-based 50/50 mix) — 4 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 the radiator drain cock and lower radiator hose area
4. Remove radiator cap slowly to release any residual pressure

Procedure

1. 1

   Drain cooling system
   Open the radiator drain cock (petcock) located at the bottom driver's side of the radiator. If petcock is seized or missing, proceed to remove lower hose to drain. Allow coolant to drain into pan until flow stops.
2. 2

   Access lower radiator hose
   Locate the lower radiator hose connection at the bottom of the radiator and at the water pump inlet on the passenger side of the engine block. Verify clear access to both connection points.
3. 3

   Remove radiator-end hose clamp
   Using a flat blade screwdriver, loosen the worm gear clamp securing the hose to the radiator outlet neck. Slide the clamp down the hose away from the radiator connection. If clamp is severely corroded, cut it off and discard.
4. 4

   Remove water pump-end hose clamp
   Loosen the worm gear clamp at the water pump inlet connection on the engine block. Slide clamp down the hose away from the connection point.
5. 5

   Remove lower radiator hose
   Twist the hose back and forth while pulling to break it free from both the radiator outlet and water pump inlet. The hose may be stuck due to age and corrosion. If necessary, carefully cut the old hose lengthwise with a utility knife to remove it without damaging the metal fittings. Allow any remaining coolant to drain.
6. 6

   Clean connection surfaces
   Use a wire brush or shop towel to clean the radiator outlet neck and water pump inlet thoroughly. Remove all old rubber residue, corrosion, and debris. Inspect both metal fittings for cracks or damage that would prevent a proper seal.
7. 7

   Install new hose clamps
   Slide new worm gear clamps onto the new lower radiator hose before installation. Position one clamp approximately 2 inches from each end of the hose.
8. 8

   Install hose to water pump
   Push the new lower radiator hose firmly onto the water pump inlet fitting on the engine block. Ensure the hose is seated fully against the bead on the metal fitting. Slide the clamp into position approximately 1/4 inch from the end of the hose and tighten securely with screwdriver.
9. 9

   Install hose to radiator
   Route the hose to the radiator outlet at the bottom of the radiator and push firmly onto the outlet neck. Verify the hose is fully seated. Position the clamp approximately 1/4 inch from the hose end and tighten securely.
10. 10

    Close drain and refill system
    Close the radiator drain cock tightly. Using a funnel, slowly pour coolant mixture into the radiator until it reaches the bottom of the filler neck. Pause periodically to allow air bubbles to escape.
11. 11

    Burp cooling system
    Start the engine and allow it to reach operating temperature with the radiator cap still off. The thermostat will open and coolant level will drop as air is purged. Add additional coolant as needed to maintain proper level. Rev engine to 2000 RPM several times to help release trapped air.
12. 12

    Final fill and cap installation
    With engine at operating temperature and thermostat open, top off radiator to proper level. Install radiator cap securely. Check overflow reservoir and fill to cold mark if equipped.

Reassembly

1. Verify all hose clamps are tight and properly positioned
2. Wipe down all components and check for any coolant leaks
3. Ensure no tools or rags are left in engine compartment

Verification

• Inspect both hose connections for any signs of coolant seepage while engine is running
• Allow engine to reach full operating temperature and verify no leaks at hose connections
• Check coolant level after engine cools and top off if necessary
• Recheck coolant level after first drive cycle and again after 24 hours
• Verify heater produces hot air, confirming proper coolant circulation and no airlock

More procedures for this vehicle