Radiator Hoses - Both

Replace both upper and lower radiator hoses on the 1970 AMC Rebel Machine 390ci V8 to prevent coolant leaks and overheating.

Warnings

Tools required

Parts

• Upper radiator hose × 1 — 1970 AMC 390 V8 upper hose
• Lower radiator hose × 1 — 1970 AMC 390 V8 lower hose
• Hose clamps (1.5-2 inch) × 4 — Worm gear or spring type

Fluids

• Ethylene glycol coolant (50/50 mix) — 4 qt

Preparation

1. Ensure engine is completely cold to the touch
2. Park vehicle on level surface and engage parking brake
3. Place drain pan underneath radiator drain petcock (driver side bottom of radiator)
4. Remove radiator cap slowly to release any residual pressure
5. Open radiator drain petcock and drain coolant into pan until level is below lower hose connection

Procedure

1. 1

   Remove upper radiator hose clamps
   Locate the upper radiator hose running from the top passenger side of the radiator to the thermostat housing on the engine. Use flathead screwdriver or hose clamp pliers to loosen the clamp at the radiator end, then loosen the clamp at the thermostat housing end. Slide clamps away from connection points along the hose.
2. 2

   Remove upper radiator hose
   Twist the upper hose back and forth while pulling to break the seal at both ends. If hose is stuck, carefully work a flathead screwdriver between hose and fitting to break seal. Remove hose completely and allow any remaining coolant to drain into pan. Inspect hose for cracks, bulges, or deterioration to confirm replacement was needed.
3. 3

   Remove lower radiator hose clamps
   Locate the lower radiator hose running from the bottom driver side of the radiator to the water pump inlet on the engine front. This hose is more difficult to access. Loosen the clamp at the radiator end first, then reach behind the water pump pulley to loosen the clamp at the water pump inlet. Slide clamps along the hose away from connections.
4. 4

   Remove lower radiator hose
   Twist and pull the lower hose from both connections. You may need to work from underneath the vehicle for better access to the water pump end. Expect additional coolant to drain when the lower hose is removed. Remove hose completely and allow to drain.
5. 5

   Clean radiator and engine fittings
   Use wire brush and shop rags to clean all four hose connection points: radiator upper and lower necks, thermostat housing outlet, and water pump inlet. Remove any old rubber residue, corrosion, or buildup. Inspect fittings for damage, cracks, or excessive corrosion that could cause leaks. The fittings should be smooth and clean for proper seal.
6. 6

   Install lower radiator hose
   Slide two new hose clamps onto the lower radiator hose before installation. Position hose so any bends or curves match the routing of the original hose. Push hose firmly onto the radiator lower neck first, ensuring it seats fully (typically 1.5-2 inches onto the neck). Then route hose to water pump inlet and push firmly onto inlet fitting. Hose should be fully seated on both ends with no gaps visible between hose and fitting.
7. 7

   Tighten lower radiator hose clamps
   Position clamps approximately 0.5 inch from the end of each fitting. Tighten clamps firmly with flathead screwdriver or pliers until snug, but do not overtighten as this can cut into the hose. Clamps should compress hose enough to prevent leaks but not deform the hose excessively. Double-check that hose is still fully seated on both fittings after tightening.
8. 8

   Install upper radiator hose
   Slide two new hose clamps onto the upper radiator hose. Push hose onto thermostat housing outlet first, ensuring full seating onto the fitting. Route hose to the radiator upper neck and push firmly until fully seated. Check that hose routing does not interfere with fan blades, belts, or any engine accessories.
9. 9

   Tighten upper radiator hose clamps
   Position clamps approximately 0.5 inch from end of each fitting. Tighten both clamps firmly until hose is compressed and secure. Verify hose is still fully seated on both fittings and does not have excessive slack or tension that could cause premature failure.
10. 10

    Close drain and refill cooling system
    Close the radiator drain petcock tightly. Fill radiator through radiator cap opening with 50/50 premixed coolant or properly mixed ethylene glycol coolant and distilled water. Fill until coolant is visible at the base of the filler neck. Start engine and allow to idle with heater on maximum heat setting.
11. 11

    Burp cooling system and check level
    As engine warms to operating temperature (approximately 180°F), watch coolant level and add more as air bubbles escape and level drops. Squeeze upper radiator hose several times to help release trapped air. When thermostat opens (upper hose will become hot), top off coolant to proper level. Install radiator cap securely.

Reassembly

1. No disassembly of other components was required for this procedure
2. Ensure all hose clamps are positioned properly and tightened securely
3. Verify coolant level is correct and radiator cap is installed properly

Verification

• With engine at operating temperature, visually inspect all four hose connections for coolant leaks
• Check for wetness or drips at radiator necks, thermostat housing, and water pump inlet
• Squeeze upper and lower hoses to verify they are firm when engine is hot, indicating proper cooling system pressure
• Monitor temperature gauge during test drive to ensure engine maintains normal operating temperature
• Recheck coolant level after engine cools completely and top off if necessary
• Inspect connections again after 50-100 miles of driving and retighten clamps if needed

More procedures for this vehicle