This procedure covers the replacement of valve stem seals on the 3.5L EcoBoost V6 engine, requiring removal of camshafts and valve train components to access the valve springs and seals.

Warnings

Tools required

Parts

• Valve stem seal set (intake and exhaust) × 1 — Motorcraft SEAL-KIT-3.5EB or equivalent
• Valve cover gaskets (left and right) × 2 — Use OEM specification
• Spark plug tube seals × 6 — Use OEM specification
• Camshaft cover gaskets × 2 — Use OEM specification
• VCT solenoid seals × 4 — Use OEM specification
• Timing chain tensioner seals × 2 — Use OEM specification
• RTV silicone sealant (Motorcraft TA-31) × 1 — Motorcraft TA-31

Fluids

• Motorcraft 0W-20 Full Synthetic — 6 qt
• Motorcraft Orange Coolant — 2 qt

Preparation

1. Ensure engine is completely cold before beginning work
2. Disconnect negative battery cable and wait 10 minutes for airbag system to deplete
3. Drain engine coolant into suitable container by opening radiator petcock and lower radiator hose
4. Remove engine cover by pulling upward on cover clips
5. Remove air intake system including air filter housing and intake tubes
6. Disconnect and remove both ignition coils from all six cylinders
7. Label and photograph all electrical connections, vacuum lines, and hose routing before disconnection
8. Support engine with hoist or support bar from above as motor mounts may need slight adjustment for access
9. Place vehicle on level surface with parking brake engaged and wheel chocks in place

Procedure

1. 1

   Remove spark plugs and prepare cylinders
   Remove all six spark plugs using a spark plug socket. Inspect plugs for oil fouling which confirms valve seal failure. Keep plugs organized by cylinder position. Clean debris from spark plug wells using compressed air before removal to prevent contamination entering cylinders.
2. 2

   Remove valve covers
   Disconnect PCV hoses, breather tubes, and any wiring harnesses attached to valve covers. Remove valve cover bolts in reverse of tightening sequence (outside to inside pattern). Carefully lift valve covers off cylinder heads. If covers are stuck, gently tap with rubber mallet - do not pry between cover and head as this will damage sealing surfaces.
3. 3

   Position engine to TDC cylinder 1
   Rotate crankshaft clockwise using a socket on the crankshaft pulley bolt until cylinder 1 is at top dead center on compression stroke. Both intake and exhaust valves should be closed. Verify timing marks on camshaft VCT actuators align with marks on camshaft bearing caps. Take clear photographs of all timing mark positions from multiple angles.
   ⚠Never rotate engine counterclockwise as this can damage timing chains and guides.
4. 4

   Install timing chain locking tools
   Install timing chain holding tools to lock chains in position before removing camshaft VCT actuators. Follow tool manufacturer instructions for proper placement. The timing chains must remain locked throughout camshaft removal to prevent timing loss. Mark position of VCT actuators relative to camshafts with paint marker before removal.
5. 5

   Remove camshaft VCT actuators
   Using camshaft holding tool to prevent rotation, remove VCT actuator bolts from all four camshafts (two intake, two exhaust). Carefully remove actuators without rotating them internally. Place actuators on clean surface in exact orientation they were removed - do not allow them to rotate or internal timing will be lost. Keep hardware organized by position.
   ⚠VCT actuators have internal phasing that must not be disturbed. Mark orientation and do not rotate actuator components.
6. 6

   Remove camshaft bearing caps and camshafts
   Loosen camshaft bearing cap bolts in reverse sequence (outside to inside) in multiple passes, no more than 1/4 turn per pass to prevent warping. Remove bearing caps and keep them in exact order - they are not interchangeable. Mark caps with cylinder head side and position. Carefully lift camshafts straight up from cylinder heads and place on clean, padded surface. Inspect camshaft lobes and journals for wear or scoring.
7. 7

   Remove rocker arms and hydraulic lash adjusters
   Remove all rocker arms from both cylinder heads. Each rocker arm has a corresponding hydraulic lash adjuster beneath it. Remove all lash adjusters and keep them in organized order by cylinder and valve position. Store lash adjusters upright in clean engine oil to prevent air from entering. Mark intake vs exhaust positions as they may have different wear patterns.
8. 8

   Set up for valve seal replacement on cylinder 1
   Thread compressed air adapter into cylinder 1 spark plug hole. Rotate crankshaft if needed to position piston approximately 1/4 turn before TDC to provide maximum valve-to-piston clearance. Apply 90-100 PSI shop air pressure to hold valves against their seats. Maintain air pressure throughout seal replacement process for this cylinder. Listen for air leaks past rings at oil filler or crankcase - some leakage is normal but excessive leaking may prevent valve retention.
   ⚠️Never release air pressure while valve spring is compressed or valve will drop into cylinder causing severe engine damage.
9. 9

   Replace valve seals for cylinder 1
   Using valve spring compressor tool, carefully compress valve spring on first valve. Remove valve keepers using magnetic tool or small screwdriver. Slowly release spring compressor and remove valve spring retainer and valve spring. Remove old valve seal using pliers or seal removal tool - pull straight up to avoid damaging valve guide. Lubricate new seal with clean engine oil. Using seal installation tool, carefully drive new seal onto valve guide until it bottoms on guide shoulder. Install valve spring, retainer, and compress spring. Install valve keepers in valve stem groove, ensuring they are fully seated. Release compressor slowly and verify keepers are locked in place - tap valve stem lightly with plastic hammer to confirm. Repeat for all valves in cylinder 1 (2 intake, 2 exhaust).
10. 10

    Complete remaining cylinders sequentially
    Remove air pressure from cylinder 1. Move to cylinder 2 and repeat step 8 and 9 process. Continue through all six cylinders in firing order sequence (1-4-2-5-3-6) or numerical order. For each cylinder: install air pressure adapter, apply 90-100 PSI air pressure, compress springs, remove keepers and springs, replace seals, reinstall springs and keepers, verify keeper engagement, then move to next cylinder. Maintain organization and ensure intake seals are used on intake valves and exhaust seals on exhaust valves.
    ℹ️Take your time with each valve. Rushing this process can result in dropped valves or improperly seated keepers.
11. 11

    Reinstall hydraulic lash adjusters and rocker arms
    Inspect all lash adjusters for damage or excessive wear. Ensure lash adjusters have been stored upright in oil and are not bled down. Install each lash adjuster in its original position. Install rocker arms over valve stems and lash adjusters in their original positions. Verify each rocker arm moves freely on its lash adjuster and valve stem tip.
12. 12

    Reinstall camshafts
    Lubricate all camshaft journals and lobes with clean engine oil. Carefully place each camshaft back in its original position in cylinder head, ensuring cam lobes are positioned to match your timing mark photographs. Verify camshaft is fully seated in journal saddles. Lubricate camshaft bearing cap contact surfaces with engine oil.
13. 13

    Install camshaft bearing caps
    Install camshaft bearing caps in their exact original positions - refer to your markings. Hand-start all cap bolts to prevent cross-threading. Tighten camshaft cap bolts in sequence from center outward in multiple passes as specified, gradually bringing caps down evenly. Final torque to specification. Verify camshaft rotates freely by hand after cap installation.
    Torque spec

    Camshaft Cap Bolts14 Nm (10 lb-ft)
14. 14

    Reinstall VCT actuators and verify timing
    Ensure timing chain locking tools are still in place. Install VCT actuators onto camshafts in exact same orientation as removed - reference your paint marks. Using camshaft holding tool, install and torque VCT actuator bolts to specification. Verify all timing marks align correctly with marks on bearing caps. Remove timing chain locking tools. Manually rotate crankshaft two complete revolutions clockwise and recheck all timing marks - they must realign exactly.
    ⚠️If timing marks do not realign after two crankshaft rotations, stop immediately. Timing is incorrect and engine must not be started.
15. 15

    Prepare and install valve covers
    Thoroughly clean valve cover and cylinder head gasket surfaces using plastic scraper - remove all old gasket material and oil residue. Clean spark plug tube areas. Install new spark plug tube seals into valve cover. Apply thin bead of RTV silicone sealant to timing chain cover-to-cylinder head junction areas as specified in service manual. Install new valve cover gaskets. Position valve covers onto cylinder heads and hand-start all bolts. Tighten valve cover bolts in sequence from center outward to specification.
    Torque spec

    Cover Bolts19 Nm (14 lb-ft)
16. 16

    Reinstall spark plugs and ignition coils
    Apply anti-seize compound sparingly to spark plug threads. Install spark plugs and torque to specification. Install ignition coils into spark plug wells and secure with mounting bolts. Reconnect all ignition coil electrical connectors.
    Torque spec

    Spark Plugs - Aluminum Head20 Nm (15 lb-ft)
17. 17

    Reinstall remaining components
    Reconnect all vacuum lines, hoses, and electrical connections per your photographs and labels. Install air intake system components. Refill cooling system with proper coolant mixture. Refill engine with correct grade and amount of fresh engine oil. Reconnect negative battery cable.

Reassembly

1. Double-check all timing marks align correctly before initial startup
2. Verify all electrical connectors are fully seated and locked
3. Confirm all hose clamps and vacuum lines are properly secured
4. Ensure no tools or shop towels remain in engine compartment
5. Check engine oil level on dipstick after filling - should be at full mark

Verification

• Perform initial engine start and listen for unusual valve train noise - should be quiet after brief startup lash adjuster priming period
• Check for oil leaks around valve covers while engine is running - retorque valve cover bolts if seepage is observed
• Allow engine to reach operating temperature and verify smooth idle with no misfires
• Monitor for white smoke from exhaust during first 10-15 minutes (residual oil on valves from installation is normal)
• After 30 minutes of runtime, check engine oil level and top off if needed
• After 500 miles, inspect valve covers for oil seepage and retorque if necessary
• Monitor oil consumption over next 1000 miles - consumption should be significantly reduced if valve seals were the issue

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