Radiator Cap

Remove and replace the radiator pressure cap on a 1972 Ford F-100 with 302ci V8 engine to restore proper cooling system pressurization.

Warnings

Tools required

Parts

• Radiator pressure cap × 1 — Stant 10230 or equivalent 13-16 PSI cap

Preparation

1. Park vehicle on level surface and set parking brake
2. Allow engine to cool completely (minimum 2 hours after operation)
3. Open hood and secure with prop rod
4. Verify engine is cool by carefully touching upper radiator hose with back of hand

Procedure

1. 1

   Inspect existing radiator cap
   Examine the current radiator cap for visible damage, corrosion, or worn gasket material. Note the pressure rating stamped on top of the cap (should be approximately 13 PSI for this application). Check for coolant residue around the radiator filler neck which may indicate a leaking cap.
2. 2

   Release residual pressure
   Even on a cold engine, slight residual pressure may remain. Place a shop rag or thick towel over the radiator cap. Press down firmly on the cap while turning counterclockwise to the first stop (safety release position). Allow any residual pressure to escape completely before proceeding.
3. 3

   Remove old radiator cap
   With the rag still in place, continue pressing down on the cap and turn counterclockwise past the safety stop until the cap releases from the filler neck threads. Lift the cap straight up and away from the radiator. Inspect the cap gaskets (both upper and lower seals) for deterioration, cracking, or hardening.
4. 4

   Inspect radiator filler neck
   Examine the radiator filler neck sealing surface for corrosion, damage, or debris. The sealing surface should be clean and smooth. Wipe away any dirt or old gasket material with a clean shop rag. Look for cracks or damage to the filler neck itself.
5. 5

   Check coolant level and condition
   With the cap removed, verify coolant level is visible near the top of the filler neck (approximately 1 inch below the top). Inspect coolant condition—should be clean and translucent per ethylene glycol 50/50 specification (typically green, but may vary with coolant brand). If coolant is rusty, contaminated, or low, address those issues before installing new cap. Verified detail (Ethylene glycol 50/50 is period-correct for a 1972 vehicle, so this is acceptable. However, the assumption that coolant must be green is only valid if conventional IAT coolant was used; not strictly an error but worth noting the color depends on the coolant type installed.): Inspect coolant condition—conventional ethylene glycol coolant (typically green) mixed at 50/50 is correct for this vehicle. Coolant should appear clean and free of rust or contamination.
6. 6

   Install new radiator cap
   Verify the new cap matches the correct pressure rating (approximately 13 PSI). Align the cap tabs with the filler neck slots. Press down firmly and turn clockwise until the cap seats against the first stop. Continue pressing down and rotating clockwise past the safety detent until the cap locks fully into place. The cap should feel secure with no lateral movement.

Reassembly

1. No additional reassembly required for this procedure

Verification

• Start engine and allow to reach normal operating temperature while monitoring for leaks around radiator cap
• Verify upper radiator hose becomes firm as system pressurizes, indicating cap is holding pressure
• Check that temperature gauge reads normal range (approximately 180-200°F)
• After engine cools, verify coolant level has not dropped significantly, which would indicate pressure loss
• Inspect overflow/expansion tank (if equipped) to ensure coolant is cycling properly through cap overflow valve

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