Perform a pressure test on the cooling system to identify leaks in hoses, radiator, water pump, heater core, and other components.

Warnings

Tools required

Parts

• Replacement coolant (if system requires draining) × 1 — Use OEM specification

Fluids

• Motorcraft Orange Coolant — 16 qt

Preparation

1. Ensure engine is completely cold to the touch (wait at least 2 hours after last operation)
2. Park vehicle on level surface and engage parking brake
3. Open hood and verify radiator cap is cool enough to touch safely
4. Gather all necessary tools and ensure adequate lighting in engine bay
5. Have drain pan ready in case coolant removal is necessary

Procedure

1. 1

   Verify coolant level and system condition
   Check coolant level in the degas bottle (coolant reservoir) on the passenger side of the engine bay. Level should be between MIN and MAX marks when cold. Inspect visible hoses, clamps, and radiator for obvious damage or wetness indicating existing leaks. Note any areas of concern for focused inspection during pressure test.
2. 2

   Remove radiator cap
   Slowly turn the radiator cap counterclockwise to the first stop and allow any residual pressure to escape. Once pressure is fully released, press down and continue turning counterclockwise to remove the cap completely. Inspect the cap gasket for cracks, hardening, or damage. Set cap aside in clean area.
   ⚠Even on a cold engine, there may be residual pressure. Turn cap slowly and listen for any hissing.
3. 3

   Install pressure tester adapter
   Select the correct adapter from your pressure tester kit that fits the F-150 radiator neck (typically a large round adapter). Ensure the adapter seating surface on the radiator is clean and free of debris. Install the adapter onto the radiator filler neck, ensuring it seats completely and forms a proper seal. Hand tighten any locking mechanism on the adapter.
4. 4

   Attach pressure tester
   Connect the pressure tester pump to the installed adapter. Verify all connections are secure. Before pumping, inspect the gauge to confirm it reads zero PSI. Check that the tester itself has no obvious leaks or damage that would prevent accurate testing.
5. 5

   Pressurize the cooling system
   Slowly pump the pressure tester to bring the system pressure to 16 PSI (the rated pressure cap specification for this vehicle). Watch the gauge carefully and stop immediately when reaching 16 PSI. Do not exceed this pressure. Observe if the gauge holds steady or begins dropping immediately.
   ⚠Do not exceed 16 PSI. Over-pressurization can damage radiator, heater core, or gaskets and create false failure points.
6. 6

   Monitor pressure gauge
   Observe the pressure gauge for 2-3 minutes without moving or disturbing the vehicle. A properly sealed system should hold 16 PSI with minimal pressure drop (less than 2 PSI over 10 minutes is acceptable). Note the rate of any pressure loss. Rapid pressure drop indicates a significant leak; slow gradual loss may indicate minor seepage.
7. 7

   Inspect radiator and hoses
   While system is pressurized, visually inspect the radiator tanks, core, and all attached hoses. Check upper and lower radiator hoses, heater hoses near the firewall, and bypass hoses. Look for coolant weeping, dripping, or spraying. Check all hose clamps for leakage. Use a flashlight to inspect underneath hose connections and behind components. Run your hand (with glove) under hoses to feel for wetness.
8. 8

   Inspect water pump and thermostat housing
   Examine the water pump (front of engine, driven by serpentine belt) for coolant leakage from the weep hole on the bottom of the pump housing or around the mounting flange. Inspect the thermostat housing and connections on the front of the engine. Check the engine block freeze plugs visible from above and sides for seepage.
   ℹ️Water pump weep hole leakage indicates bearing seal failure and requires pump replacement.
9. 9

   Check heater core and firewall connections
   Inspect the heater hoses where they pass through the firewall on the passenger side. Look inside the cab under the dashboard on the passenger side for signs of coolant leakage or sweet smell indicating heater core leak. A heater core leak may not be visible externally but will show as pressure loss without external evidence.
10. 10

    Inspect degas bottle and overflow system
    Check the degas bottle (coolant reservoir) and cap for cracks or leaks. Inspect the hose connecting the degas bottle to the radiator. Verify the overflow hose is not leaking. These plastic components can develop stress cracks that only leak under pressure.
11. 11

    Check for internal leaks
    If the system loses pressure but no external leaks are found, check the engine oil dipstick for milky discoloration indicating coolant in oil (head gasket leak). Inspect spark plug wells if accessible for coolant presence. Note that internal combustion chamber leaks will show as pressure loss without visible external leakage and may require additional testing.
12. 12

    Release pressure and remove tester
    Once inspection is complete, slowly release pressure using the tester's pressure release valve. Allow gauge to return to zero before disconnecting. Remove the pressure tester from the adapter, then remove the adapter from the radiator neck. Inspect the radiator neck seal surface for damage.
13. 13

    Reinstall radiator cap and verify coolant level
    Reinstall the radiator cap by pressing down and turning clockwise until it stops. Check coolant level in degas bottle and top off with Motorcraft Orange Coolant if needed to bring level to MAX mark when cold. If significant coolant was lost during testing or repairs, the system will need proper bleeding after refilling.

Reassembly

1. Ensure radiator cap is properly installed and seated
2. Top off coolant in degas bottle to MAX mark if needed
3. Wipe down any coolant spills in engine bay with absorbent towels
4. If leaks were found and repaired, perform pressure test again to verify repair

Verification

• Pressure gauge should hold 16 PSI for at least 10 minutes with no more than 2 PSI loss in a healthy system
• No visible coolant leaks, drips, or wetness should be present at any connections or components
• Coolant level in degas bottle remains at proper level after test
• If system failed test, document location and severity of all leaks found for repair
• Start engine and allow to reach operating temperature to verify no leaks appear during hot operation

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