Replace valve stem seals on a 2021-2024 Ford F-150 3.5L EcoBoost V6 engine to address oil consumption or smoking issues. Requires cylinder head disassembly with camshaft removal.

Warnings

Tools required

Parts

• Valve stem seals (set of 24) × 1 — Ford Motorcraft or OEM equivalent for 3.5L EcoBoost
• Valve cover gaskets (left and right) × 2 — Use OEM specification
• Camshaft cap bolts (if reuse not recommended) × 1 — Check service manual for torque-to-yield status
• Spark plug tube seals × 6 — Use OEM specification
• Timing cover gasket × 1 — Use OEM specification
• Coolant × 1 — Motorcraft Orange Coolant
• Engine oil and filter × 1 — Motorcraft 0W-20 Full Synthetic

Fluids

• Motorcraft 0W-20 Full Synthetic — 6 qt
• Motorcraft Orange Coolant — 13 qt

Preparation

1. Disconnect negative battery cable and wait 10 minutes for airbag system to discharge
2. Drain engine coolant into appropriate container by opening radiator petcock and lower hose
3. Remove engine cover by pulling upward on clip fasteners
4. Remove air intake system including air filter housing and intake tubes
5. Disconnect and remove ignition coils from all six spark plugs
6. Label and disconnect all electrical connectors from valve covers, sensors, and actuators
7. Disconnect PCV hoses and breather tubes from both valve covers
8. Remove accessory drive belt
9. Position drain pan and remove engine oil drain plug, then remove oil filter
10. Photograph timing chain alignment and cam sprocket positions for reassembly reference

Procedure

1. 1

   Remove valve covers
   Remove all valve cover bolts in reverse of tightening sequence (outside to inside pattern). Carefully lift valve covers away from cylinder heads. If stuck, gently tap with rubber mallet. Remove and discard old valve cover gaskets and spark plug tube seals.
   Torque spec

   Cover Bolts19 Nm (14 lb-ft)
2. 2

   Remove spark plugs
   Using a 9/16 inch spark plug socket, carefully remove all six spark plugs. Inspect threads in cylinder head for damage. Keep spark plugs organized by cylinder number for inspection.
   Torque spec

   Spark Plugs - Aluminum Head20 Nm (15 lb-ft)
3. 3

   Mark and remove timing components
   Rotate engine to TDC on cylinder #1 using crankshaft bolt. Verify timing marks on camshaft sprockets align with cylinder head surface. Mark timing chain to sprockets with paint marker at multiple points. Install camshaft holding tool to lock camshafts in position. Remove camshaft sprocket bolts while holding sprockets with holding tool. Carefully slide sprockets off camshafts without disturbing timing chain position.
   ⚠Do not allow timing chain to slip off crankshaft sprocket or rotate. Zip-tie chain to prevent dropping into engine.
4. 4

   Remove camshaft caps and camshafts
   Loosen camshaft cap bolts in reverse sequence (outward to center), 1/4 turn at a time in multiple passes to evenly release valve spring pressure. Remove all camshaft cap bolts and carefully lift off camshaft caps, keeping them in order and orientation. Mark each cap with cylinder head position. Lift camshafts straight up and out of cylinder head. Store camshafts in clean area where they will not roll.
   ⚠Camshaft caps are not interchangeable and must be reinstalled in exact original positions. Number or mark them clearly.
   Torque spec

   Camshaft Cap Bolts14 Nm (10 lb-ft)
5. 5

   Remove rocker arms and lash adjusters
   Remove rocker arms from cylinder head, keeping them organized by cylinder and position (intake vs exhaust). Remove hydraulic lash adjusters from their bores in the cylinder head. Place all components in organized container or numbered tray to ensure correct reinstallation. Inspect rocker arm contact surfaces for excessive wear or scoring.
   Torque spec

   Rocker Arm Bolts30 Nm (22 lb-ft)
6. 6

   Prepare for valve seal removal - Cylinder 1
   Rotate crankshaft to bring cylinder #1 piston approximately 1/4 inch before TDC. Install air pressure adapter into cylinder #1 spark plug hole and connect compressed air line (minimum 100 PSI recommended). Apply air pressure to hold both valves closed. Verify constant air pressure - any loss indicates valve not seating properly; adjust piston position slightly if needed.
   ⚠️Maintain constant air pressure throughout valve spring compression. If pressure is lost, valve and retainer can drop into cylinder causing severe damage.
7. 7

   Compress valve springs and remove keepers - Cylinder 1
   Position valve spring compressor tool on first valve spring. Carefully compress spring until keepers (locks) are accessible. Using magnetic pickup tool, remove both valve spring keepers and place in organized container. Slowly release spring compressor and remove retainer and spring. Repeat for all four valves in cylinder #1 while maintaining air pressure. Keep springs organized by cylinder and valve position.
   ⚠Valve keepers are small and easily lost. Work over clean area and use magnetic tool to prevent dropping.
8. 8

   Remove old valve seals - Cylinder 1
   Using valve seal removal pliers or carefully with standard pliers, grip old valve seal at base and pull straight up off valve guide. Seals may be tight; twist while pulling if necessary. Remove all four valve seals from cylinder #1. Inspect valve stems for scoring or damage. Clean any carbon buildup from top of valve guides using plastic scraper.
   ℹ️Old seals may be brittle and break apart during removal. Ensure all pieces are removed from cylinder head.
9. 9

   Install new valve seals - Cylinder 1
   Lightly oil new valve seal O-ring/outer diameter with clean engine oil. Place new seal on valve seal installation tool. Carefully slide seal over valve stem and guide it onto valve guide. Press seal firmly onto guide using installation tool until it bottoms against cylinder head - you should feel a definite stop. Verify seal is fully seated and square on guide. Repeat for all four valves in cylinder #1. Do not use excessive force or hammer to install seals.
   ⚠Valve seals must be installed to proper depth. Improperly seated seals will leak oil or may interfere with valve operation.
10. 10

    Reinstall valve springs and keepers - Cylinder 1
    Install valve spring and retainer over valve stem. Compress spring with spring compressor tool. Apply small amount of assembly grease to valve keepers to hold them in place. Carefully install both keepers into valve stem groove, ensuring they seat properly in retainer. Slowly release spring compressor while verifying keepers remain seated. After releasing, tap valve stem lightly with plastic hammer to ensure keepers are fully seated. Verify keepers are secure before removing air pressure. Repeat for all four valves in cylinder #1.
    ⚠Ensure both keepers are fully seated in valve stem groove before releasing spring pressure. Improperly seated keepers will cause valve failure.
11. 11

    Repeat valve seal replacement for remaining cylinders
    Remove air pressure from cylinder #1. Rotate crankshaft to bring next cylinder (following firing order: 1-4-2-5-3-6) to approximately 1/4 inch before TDC. Repeat steps 6 through 10 for each remaining cylinder: install air pressure adapter, apply air pressure, compress springs, remove keepers, remove springs, replace valve seals, reinstall springs and keepers. Work methodically through all six cylinders on both banks. Maintain organized system for tracking which cylinders are complete.
    ℹ️This is the most time-consuming portion of the job. Work carefully and methodically. Do not rush valve keeper installation.
12. 12

    Reinstall hydraulic lash adjusters and rocker arms
    Clean hydraulic lash adjuster bores with clean lint-free cloth. Lubricate each lash adjuster with clean engine oil and insert into original bore location. Install rocker arms onto their original valve positions, ensuring lash adjusters are properly seated in rocker arm socket. Verify each rocker arm moves freely on its lash adjuster. Double-check all components are in correct positions using organizational system from disassembly.
13. 13

    Reinstall camshafts and camshaft caps
    Lubricate camshaft journals and lobes with clean engine oil. Carefully lower camshafts into cylinder head, ensuring they seat properly in journal bores. Verify cam position matches timing marks. Install camshaft caps in exact original positions and orientations (markings should be visible and in correct order). Install camshaft cap bolts finger-tight. Tighten camshaft cap bolts in sequence from center outward in multiple passes (approximately 1/3 torque, 2/3 torque, then final torque) to evenly load valve springs.
    ⚠Tighten camshaft caps evenly in multiple passes. Uneven tightening can bend camshaft or damage caps.
    Torque spec

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

    Reinstall timing components
    Verify camshaft and crankshaft are still at TDC position. Align timing chain with paint marks made during disassembly. Install camshaft sprockets onto camshafts, ensuring dowel pins engage properly. Verify all timing marks align correctly - camshaft timing marks should align with cylinder head surface, and timing chain marks should match paint references. Install and tighten camshaft sprocket bolts while holding sprockets with holding tool. Remove camshaft holding/locking tools. Rotate engine by hand two complete revolutions and recheck timing mark alignment.
    ⚠️Verify timing alignment is correct before proceeding. Incorrect valve timing will cause severe engine damage.
15. 15

    Install new valve cover gaskets and reinstall covers
    Clean valve cover and cylinder head gasket surfaces thoroughly with plastic scraper and brake cleaner. Ensure all old gasket material and oil residue are removed. Install new spark plug tube seals into valve covers. Position new valve cover gaskets on cylinder heads - gaskets should fit precisely in grooves. Apply small dab of RTV sealant at front timing cover corners if specified. Carefully lower valve covers onto cylinder heads without displacing gaskets. Install valve cover bolts finger-tight, then tighten in proper sequence (inside to outside pattern) to specified torque.
    ℹ️Do not over-torque valve cover bolts. Excessive torque will damage gasket and cause oil leaks.
    Torque spec

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

    Reinstall spark plugs
    Apply small amount of anti-seize compound to spark plug threads (avoid getting anti-seize on electrodes). Thread each spark plug by hand into cylinder head to avoid cross-threading. Tighten spark plugs to specification using torque wrench and spark plug socket.
    Torque spec

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

Reassembly

1. Reconnect all electrical connectors to valve covers, sensors, and actuators using labels from disassembly
2. Reinstall PCV hoses and breather tubes to valve covers
3. Reinstall ignition coils to spark plugs and secure with mounting bolts
4. Reinstall air intake system including air filter housing and intake tubes
5. Reinstall accessory drive belt following proper routing diagram
6. Install new oil filter and reinstall oil drain plug with new crush washer
7. Refill engine with 6 quarts of Motorcraft 0W-20 full synthetic engine oil
8. Refill cooling system with 13 quarts of Motorcraft Orange Coolant (50/50 premix)
9. Bleed cooling system by running engine at 2000 RPM until thermostat opens and adding coolant as needed
10. Reinstall engine cover
11. Reconnect negative battery cable

Verification

• Start engine and verify it runs smoothly without unusual noises, misfires, or valve train noise
• Check for oil leaks around valve covers after engine reaches operating temperature
• Monitor oil pressure gauge to ensure normal pressure at idle and under load
• Verify no coolant leaks from timing cover area
• Allow engine to idle for 10 minutes and check oil level - top off if necessary
• Check for diagnostic trouble codes using scan tool - there should be no misfire or timing-related codes
• Test drive vehicle to verify normal performance and absence of smoke from exhaust under acceleration and deceleration
• After 100 miles, recheck oil level and valve cover gasket sealing
• Monitor oil consumption over next 500-1000 miles to verify seals are functioning properly

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