This procedure performs a pressure test on the cooling system to identify leaks in hoses, radiator, water pump, and other components without draining the coolant.

Warnings

Tools required

Parts

• Motorcraft Orange Coolant (if system needs topping off) × 1 — VC-3DIL-B

Fluids

• Motorcraft Orange Coolant — 0.5 qt

Preparation

1. Ensure engine has been off for at least 2 hours and is completely cool to the touch
2. Park vehicle on level ground and engage parking brake
3. Verify coolant level is at the FULL COLD mark on the overflow reservoir. Top off if needed before testing
4. Visually inspect engine bay for obvious coolant leaks, stains, or residue before pressurizing system
5. Have adequate lighting to inspect all cooling system components during the test

Procedure

1. 1

   Access the radiator cap
   Locate the radiator cap on the driver side of the radiator near the upper radiator hose. Ensure the engine is completely cool. Place a shop towel over the cap and slowly turn counterclockwise to the first stop to release any residual pressure. Wait for any hissing to stop, then press down and continue turning counterclockwise to remove the cap completely.
2. 2

   Inspect radiator filler neck
   Before attaching the pressure tester, inspect the radiator filler neck for cracks, damage, or corrosion. Check the radiator cap gasket for cracks, hardening, or deterioration. A damaged filler neck or cap will prevent proper pressure testing. Check that coolant level is visible near the top of the filler neck.
3. 3

   Install pressure tester adapter
   Select the correct adapter from your pressure tester kit that fits the Ford radiator cap opening (typically the large tapered adapter). Install the adapter onto the radiator filler neck, ensuring it seats properly against the sealing surface. The adapter should fit snugly without rocking or tilting.
4. 4

   Attach pressure tester
   Connect the pressure tester to the adapter. Ensure all connections are secure and the tester gauge reads zero PSI before pumping. If the gauge shows pressure with no pumping, there may be a connection issue or residual system pressure.
5. 5

   Pressurize the cooling system
   Slowly pump the pressure tester to bring the system up to the rated pressure on the radiator cap (typically 16 PSI for this vehicle). Do not exceed 20 PSI. Monitor the gauge as you pump. If pressure builds unusually quickly, stop and verify all connections are correct.
6. 6

   Observe initial pressure hold
   Once at rated pressure (16 PSI), stop pumping and observe the gauge for 2-3 minutes. A healthy system should hold pressure with minimal drop (no more than 1-2 PSI in 2 minutes). A rapid pressure drop indicates a significant leak. Note the pressure reading and time.
7. 7

   Inspect radiator and hoses
   With the system pressurized, systematically inspect the radiator for leaks. Check the upper and lower radiator hoses, hose clamps, and all connection points. Look for drips, seepage, or wet spots. Squeeze accessible hoses gently to check for soft spots or bulging that indicates internal deterioration. Inspect the radiator core, end tanks, and plastic-to-metal seams.
8. 8

   Inspect water pump and thermostat housing
   Inspect the water pump weep hole (located at bottom of pump) for coolant seepage, which indicates bearing seal failure. Check the thermostat housing and all coolant hose connections on the front of the engine. Use a work light and mirror to inspect the back side of the water pump and lower hoses.
9. 9

   Inspect heater hoses and overflow system
   Follow the heater hoses from the engine to the firewall, checking all connections and clamps. Inspect the coolant overflow reservoir and its hose connection to the radiator. Check the reservoir cap and verify no leaks at the tank seams. Small leaks may appear as steam or mist under pressure.
10. 10

    Check engine block and cylinder heads
    Inspect both sides of the engine block for coolant seepage. On the 5.0L Coyote engine, pay special attention to the valley area between cylinder heads, timing chain cover seams, and freeze plug locations on the sides of the block. Look for white or orange residue indicating dried coolant.
11. 11

    Monitor pressure over extended period
    Continue observing the pressure gauge for 10-15 minutes total. Re-pump to restore rated pressure if it drops, and continue inspection. Count the number of pump strokes needed to restore pressure, as this indicates leak severity. Small external leaks may take time to become visible.
12. 12

    Release pressure and remove tester
    Once testing is complete, slowly release pressure using the tester's pressure relief valve. Do not remove the tester while system is pressurized. After pressure reaches zero on the gauge, disconnect the tester and remove the adapter from the radiator filler neck.
13. 13

    Check coolant level and reinstall cap
    Inspect coolant level in the radiator. If level dropped during testing, top off with Motorcraft Orange Coolant (VC-3DIL-B) as needed. Reinstall the radiator cap by pressing down and turning clockwise until it clicks into the locked position. Verify the coolant overflow reservoir is at the FULL COLD mark.

Reassembly

1. Ensure radiator cap is properly installed and locked in place
2. Wipe down any coolant spills in the engine bay with shop towels
3. If leaks were found and repaired, repeat the pressure test to verify repairs before returning vehicle to service

Verification

• System should hold rated pressure (16 PSI) for at least 10 minutes with no more than 2 PSI drop
• No visible coolant leaks, drips, seepage, or wet spots should be present anywhere in the cooling system
• If system fails to hold pressure, identify and repair leaks, then retest
• For internal leaks (head gasket), pressure may drop with no visible external leaks. Consider combustion leak test if pressure drops without external evidence
• Document test results including starting pressure, time duration, final pressure, and any leaks found with locations

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