This procedure tests the cooling system for leaks using a pressure tester to identify failed components such as hoses, radiator, water pump, or head gasket issues.

Warnings

Tools required

Parts

• Radiator cap (if damaged during testing) × 1 — Use OEM specification

Fluids

• Motorcraft Orange Coolant — 0.5 qt

Preparation

1. Ensure engine is completely cold to the touch (minimum 2 hours after last operation)
2. Park vehicle on level surface and engage parking brake
3. Open hood and ensure adequate lighting in engine bay
4. Verify cooling system is filled to proper level before testing
5. Have drain pan positioned under radiator in case pressure relief is needed

Procedure

1. 1

   Access and inspect radiator cap
   Locate the radiator cap on the upper radiator tank on the driver side of the engine bay. Visually inspect the cap for cracks, damaged sealing surfaces, or deteriorated rubber gasket. Place a clean rag over the cap, then slowly turn counterclockwise to the first stop to release any residual pressure. Wait 10 seconds, then remove cap completely.
2. 2

   Verify coolant level and condition
   Look into the radiator filler neck and verify coolant is visible at the top. If low, add Motorcraft Orange Coolant until level reaches the bottom of the filler neck. Check coolant color - it should be orange/red. Brown or rusty coolant indicates contamination. Note any oil film on coolant surface which may indicate head gasket or oil cooler failure.
3. 3

   Select and install pressure tester adapter
   Choose the correct adapter from your pressure tester kit that matches the radiator cap opening on the 2021-2024 F-150 (typically a Ford-style bayonet adapter). Thread or lock the adapter onto the pressure tester pump according to manufacturer instructions. Install the adapter assembly onto the radiator filler neck, ensuring it seats properly and locks into place just like the original cap.
4. 4

   Pressurize the cooling system
   Slowly pump the pressure tester handle while watching the gauge. Build pressure to 16 PSI, which is the typical operating pressure for this cooling system (verify on original radiator cap rating). Do not exceed 20 PSI. Stop pumping once target pressure is reached.
   ⚠Pump slowly and watch gauge carefully. Rapid pumping can spike pressure and damage components.
5. 5

   Monitor pressure hold
   Observe the pressure gauge for 2 minutes without pumping. The system should hold pressure with minimal drop (no more than 2 PSI in 2 minutes is acceptable). A rapid pressure drop indicates a significant leak. A slow, steady drop may indicate a minor leak or normal seepage through hose materials.
6. 6

   Inspect external cooling system components
   While system is pressurized, systematically inspect all cooling system components. Check radiator tanks and core for seepage, all hose connections and clamps, water pump weep hole (located at bottom of pump), thermostat housing, heater hose connections at firewall, overflow tank and cap, and EGR cooler connections if equipped. Look for wetness, drips, or visible coolant spray. Use a flashlight to inspect hard-to-see areas.
7. 7

   Check for internal leaks
   Remove engine oil dipstick and check for milky discoloration indicating coolant in oil. Check overflow tank for excessive bubbling which may indicate combustion gases entering cooling system (head gasket failure). Listen for hissing sounds that may indicate leak location. If pressure dropped but no external leaks found, suspect heater core leak inside cabin - check passenger floor carpet for wetness.
8. 8

   Test radiator cap function
   Release pressure from system using tester release valve. Remove pressure tester assembly from radiator. Install the radiator cap onto the pressure tester's cap testing adapter (if your kit includes this feature). Pump tester and verify cap releases pressure at its rated specification (typically 16 PSI, verify on cap). Cap should hold pressure below rating and release cleanly at specified pressure. Replace cap if it releases early or fails to release.
9. 9

   Release pressure and remove tester
   If tester was reinstalled for additional checks, slowly release all pressure using the tester's pressure release valve. Once gauge reads zero, unlock and remove the pressure tester adapter from the radiator filler neck. Wipe the filler neck area clean of any spilled coolant.
10. 10

    Top off coolant and reinstall cap
    Check coolant level in radiator and add Motorcraft Orange Coolant if needed to bring level to bottom of filler neck. Also check overflow tank and fill to COLD FILL line if low. Clean radiator cap sealing surfaces and filler neck with clean rag. Install radiator cap by aligning tabs and turning clockwise until it locks into place with a firm click.

Reassembly

1. Ensure radiator cap is properly locked into place
2. Verify all tools and rags are removed from engine bay
3. Check ground around vehicle for any coolant drips or spills and clean if necessary

Verification

• Start engine and allow to reach normal operating temperature while monitoring temperature gauge
• Check for leaks around all inspected areas with engine at operating temperature
• Verify heater produces hot air at idle and temperature gauge remains in normal range
• After engine cools, recheck coolant level in both radiator and overflow tank - top off if needed
• If test revealed leaks, document location and severity for repair planning

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