This procedure covers replacement of a single valve spring on the 3.5L EcoBoost engine, requiring removal of the affected valve cover, rocker arm, and using compressed air to hold the valve in place during spring removal and installation.

Warnings

Tools required

Parts

• Valve spring (specify intake or exhaust) × 1 — Use OEM specification
• Valve stem seal × 1 — Use OEM specification
• Valve cover gasket (right or left bank) × 1 — Use OEM specification
• Valve cover bolt grommets × 1 — Use OEM specification
• Spark plug (if threads damaged) × 1 — Motorcraft SP-520 or equivalent
• Anti-seize compound × 1 — Use OEM specification

Preparation

1. Ensure engine is completely cold to prevent burns and allow components to contract to normal dimensions
2. Disconnect negative battery cable and wait 10 minutes for airbag system discharge
3. Remove engine cover by pulling upward on the front and rear to release clips
4. Remove air intake system components as needed to access the affected valve cover
5. If working on right bank (passenger side), remove intercooler pipes and charge air cooler as needed for access
6. If working on left bank (driver side), remove PCV hose and any interfering wiring harnesses
7. Label and photograph all electrical connectors and vacuum lines before disconnection
8. Place clean shop towels around the work area to catch any falling components

Procedure

1. 1

   Remove valve cover
   Disconnect ignition coils and move wiring harness aside. Remove all valve cover bolts in reverse of tightening sequence (outside to inside pattern). Carefully break the seal by tapping gently with a rubber mallet if stuck. Lift valve cover straight up to avoid damaging gasket sealing surfaces. Inspect gasket and bolt grommets - replace if damaged.
2. 2

   Identify and access affected valve
   Locate the cylinder with the failed valve spring. Count from front of engine: right bank is cylinders 1-2-3, left bank is cylinders 4-5-6. Remove the spark plug from the affected cylinder using a spark plug socket. Inspect threads for damage. If carbon buildup is present in spark plug well, clean thoroughly before proceeding.
3. 3

   Position piston and install air line
   Rotate the engine by hand using a socket on the crankshaft bolt to bring the affected piston to approximately 20-30 degrees before top dead center (TDC) on the compression stroke. Both intake and exhaust valves should be closed. Install the compressed air adapter into the spark plug hole and connect shop air at 90-100 PSI. You should hear air pressure holding the valves closed. Verify pressure is holding by listening for leaks at the exhaust or intake.
   ⚠️If air pressure leaks excessively from the exhaust or throttle body, the piston is not positioned correctly. Reposition the piston closer to TDC.
4. 4

   Remove rocker arm assembly
   Identify the rocker arm for the affected valve. Note the position of the camshaft lobe - if it is pointing toward the rocker arm (under load), carefully rotate the camshaft slightly using a wrench on the camshaft hex until the lobe points away from the rocker arm. Remove the rocker arm bolt and carefully lift the rocker arm assembly from the cylinder head. Keep the rocker arm, roller follower, and bolt together in a labeled container.
5. 5

   Compress valve spring and remove keepers
   Position the valve spring compressor tool over the valve spring, ensuring it seats properly on the spring retainer and cylinder head. Slowly compress the valve spring until the valve keepers are fully unloaded. Using a magnet or keeper removal tool, carefully extract both valve keeper halves and place them in a magnetic parts tray. Slowly release tension on the compressor tool and remove the spring retainer. If retainer is stuck, tap gently while maintaining air pressure.
   ⚠Do not release air pressure at any time during this or subsequent steps until reassembly is complete.
6. 6

   Remove valve spring and seal
   Lift the valve spring straight up and off the valve stem. Remove the valve stem seal by pulling upward or using a valve seal removal tool. Inspect the valve stem for scoring, wear, or damage. Check the valve spring seat area in the cylinder head for debris or damage. Clean the area with a lint-free cloth if needed.
7. 7

   Install new valve stem seal
   Lightly lubricate the new valve stem seal with clean engine oil. Carefully slide the new seal down the valve stem, ensuring it does not catch or tear on the valve keeper grooves. Use a seal installation tool or appropriate size deep socket to press the seal onto the valve guide until it seats fully. The seal should sit flush with the spring seat surface.
8. 8

   Install new valve spring
   Place the new valve spring over the valve stem, ensuring it seats properly on the spring seat. Verify the spring is oriented correctly (if directional - closer-wound coils typically face the cylinder head). Position the spring retainer on top of the valve spring, aligning it with the valve stem.
9. 9

   Compress spring and install keepers
   Position the valve spring compressor and carefully compress the new valve spring until the keeper grooves on the valve stem are fully exposed. Apply a small amount of grease to the keeper grooves to hold the keepers in place during installation. Carefully position both keeper halves in the valve stem grooves, ensuring they are fully seated and centered. Slowly release the spring compressor while watching to ensure the keepers remain properly seated. Once the retainer contacts the keepers, tap the retainer gently with a soft mallet while releasing final tension to fully seat the keepers.
10. 10

    Verify keeper installation
    Remove the spring compressor tool completely. Using a soft brass drift or plastic tool, tap the top of the valve stem firmly to verify the keepers are locked in place. The retainer should not move. Visually inspect that both keeper halves are fully engaged in the valve stem grooves and supporting the retainer evenly.
    ⚠If the keepers are not fully seated, the valve spring could fail immediately upon starting the engine, causing catastrophic damage.
11. 11

    Reinstall rocker arm
    Rotate the camshaft if necessary so the cam lobe is pointing away from the valve (lobe at base circle). Position the rocker arm assembly over the valve stem and cam lobe, ensuring proper alignment. Install the rocker arm bolt hand-tight, then torque to specification with the cam lobe pointing away from the rocker arm. Verify the rocker arm moves freely and contacts the valve stem tip properly.
    Torque spec

    Rocker Arm Bolts30 Nm (22 lb-ft)
12. 12

    Remove air pressure and reinstall spark plug
    Carefully disconnect the compressed air line from the spark plug adapter and remove the adapter from the cylinder head. Inspect the spark plug threads in the cylinder head. If damaged, chase threads with appropriate tap. Apply anti-seize compound to the spark plug threads. Install the spark plug and torque to specification for aluminum heads.
    Torque spec

    Spark Plugs - Aluminum Head20 Nm (15 lb-ft)
13. 13

    Reinstall valve cover
    Clean all gasket surfaces on the cylinder head and valve cover with a plastic scraper and brake cleaner. Ensure no debris or old gasket material remains. Install new valve cover gasket and bolt grommets. Position the valve cover carefully onto the cylinder head, aligning all bolt holes. Install all valve cover bolts hand-tight, then torque in the proper sequence (center outward) to specification.
    Torque spec

    Cover Bolts19 Nm (14 lb-ft)
14. 14

    Reinstall remaining components
    Reconnect all ignition coils and electrical connectors removed during disassembly. Reinstall any wiring harnesses, vacuum lines, PCV hoses, and intake or intercooler components. Reinstall the engine cover. Reconnect the negative battery cable.

Reassembly

1. Double-check that all electrical connectors are properly seated and locked
2. Verify all fasteners have been reinstalled and properly torqued
3. Ensure no tools or parts have been left in the engine compartment

Verification

• Start the engine and listen for any unusual valve train noise from the repaired cylinder
• Check for oil leaks around the valve cover gasket
• Allow engine to reach operating temperature and verify smooth idle
• Perform a cylinder contribution test or monitor misfire counts to confirm the affected cylinder is operating normally
• Road test the vehicle under light and moderate load to verify normal operation
• Recheck valve cover bolts for proper torque after the engine has cooled from the test drive

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