Replace the timing chain guide on a 3.5L EcoBoost engine, requiring front engine accessory removal, timing cover removal, and timing component access.

Warnings

Tools required

Parts

• Timing chain guide × 1 — Use OEM Ford specification
• Timing cover gasket × 1 — Use OEM Ford specification
• Valve cover gaskets (both banks) × 2 — Use OEM Ford specification
• Crankshaft front seal × 1 — Use OEM Ford specification
• Engine oil and filter × 1 — Motorcraft FL-910S or equivalent
• Coolant × 1 — Motorcraft Orange Coolant VC-7-B

Fluids

• Motorcraft 5W-20 Synthetic Blend — 6 qt
• Motorcraft Orange Coolant — 13 qt

Preparation

1. Ensure engine is completely cold
2. Disconnect negative battery cable
3. Remove engine cover (pull upward on cover)
4. Drain engine coolant from radiator petcock and lower radiator hose into appropriate container
5. Drain engine oil and remove oil filter
6. Raise and support vehicle securely on jack stands
7. Remove front skid plate if equipped
8. Remove right front wheel and inner fender splash shield for access
9. Place drain pan under vehicle for any residual coolant or oil
10. Support engine from above using engine support fixture or from below with jack on oil pan (use wood block)

Procedure

1. 1

   Remove Serpentine Belt and Accessories
   Rotate serpentine belt tensioner clockwise and remove belt. Remove power steering pump (leave lines attached) and set aside. Remove alternator and bracket assembly. Disconnect and remove A/C compressor (leave lines attached) and secure to frame. Label all electrical connectors during removal.
2. 2

   Remove Coolant System Components
   Disconnect upper and lower radiator hoses from engine. Remove thermostat housing and set aside. Remove coolant bypass tube. Disconnect heater hoses at engine connections. Remove any remaining coolant lines that interfere with timing cover access.
3. 3

   Remove Valve Covers
   Disconnect ignition coils from both banks and remove. Disconnect PCV hoses and any vacuum lines from valve covers. Remove valve cover bolts in reverse of tightening sequence. Carefully remove both valve covers and set aside. Clean mating surfaces thoroughly.
4. 4

   Remove Front Engine Mount and Crankshaft Pulley
   Remove right side engine mount bolts. Carefully lower or raise engine slightly for clearance (approximately 1-2 inches). Use crankshaft holding tool to prevent rotation. Use breaker bar to remove crankshaft pulley bolt (turns counterclockwise). Remove crankshaft pulley and harmonic balancer.
   ⚠Crankshaft pulley bolt is extremely tight. Ensure holding tool is secure to prevent engine rotation damage.
   Torque spec

   Crankshaft pulley bolt (stretch, replace)90 Nm (66 lb-ft)
5. 5

   Remove Timing Cover
   Remove all timing cover bolts noting locations of different length bolts (8mm bolts are located at specific positions). Carefully pry timing cover away from engine block using plastic tools at pry points. Remove timing cover and gasket. Inspect crankshaft seal and replace if worn.
   ⚠Do not pry against gasket mating surfaces. Use only designated pry points to avoid damage.
6. 6

   Verify and Lock Timing Position
   Rotate crankshaft clockwise to TDC position for cylinder #1 (crankshaft keyway at 12 o'clock). Install crankshaft timing pin in block to lock crankshaft. Verify camshaft lobes for cylinder #1 are pointing outward (base circle position). Install camshaft holding tools (303-1248 or equivalent) on both intake and exhaust camshafts for both banks.
   ⚠️Verify timing pin is fully seated and crankshaft cannot rotate before proceeding. Improper timing will destroy engine.
7. 7

   Remove Timing Chain Tensioners
   Release tension on both primary timing chain tensioners by pushing tensioner plunger inward and inserting lock pin. Remove tensioner bolts and remove both primary timing chain tensioners. Note orientation and routing for reassembly.
8. 8

   Remove Timing Chain Guides
   Remove timing chain guide bolts from the worn or damaged guide. For the primary guide, this includes the upper and lower guide bolts. Carefully remove the timing chain guide, noting its position and orientation. Inspect adjacent guides for wear. If replacing multiple guides, remove and replace one at a time to maintain chain position.
   ⚠Inspect guide closely for cracks or severe wear grooves. If guide material is missing, inspect oil pan for debris.
   Torque spec

   Chain guide bolts12 Nm (9 lb-ft)
9. 9

   Install New Timing Chain Guide
   Position new timing chain guide in exact location of old guide. Ensure timing chain is properly seated in guide groove. Install guide bolts and tighten to specification in a crisscross pattern. Verify chain moves freely and guide is secure. Double-check timing pin and camshaft holding tools remain in position.
   ℹ️New guides may have protective coating. This is normal and does not need to be removed.
   Torque spec

   Chain guide bolts12 Nm (9 lb-ft)
10. 10

    Reinstall Timing Chain Tensioners
    Verify tensioner plungers are compressed and lock pins are installed. Install both primary timing chain tensioners and tighten bolts to specification. Remove lock pins from tensioners to apply tension to chains. Verify chains are properly tensioned and guides are not deflecting excessively.
11. 11

    Verify Timing and Remove Holding Tools
    With tensioners installed, carefully remove camshaft holding tools from all four camshafts. Remove crankshaft timing pin. Manually rotate crankshaft two complete revolutions clockwise (viewed from front). Reinstall crankshaft timing pin - it should slide in freely at TDC. Reinstall camshaft holding tools - they should fit without force. If any tool does not fit properly, timing is incorrect and must be corrected.
    ⚠️If timing verification fails, do not proceed. Remove tensioners and repeat timing procedure. Starting engine with incorrect timing will cause valve-to-piston contact.
12. 12

    Install Timing Cover
    Remove all timing holding tools. Clean timing cover and engine block mating surfaces thoroughly with gasket scraper and solvent. Apply thin bead of RTV silicone to corners where oil pan meets engine block (four locations). Install new timing cover gasket. Position timing cover and install all bolts finger tight. Tighten 8mm bolts first in proper sequence, then tighten remaining bolts in sequence.
    ℹ️Follow torque sequence exactly as specified in service manual. Improper sequence can cause oil leaks.
13. 13

    Reinstall Crankshaft Pulley and Front Mount
    Install new crankshaft front seal if removed. Install harmonic balancer and crankshaft pulley. Apply small amount of engine oil to crankshaft pulley bolt threads. Install and tighten crankshaft pulley bolt to specification using holding tool. Reposition engine to original position. Install right side engine mount and tighten bolts.
    Torque spec

    Crankshaft pulley bolt (stretch, replace)90 Nm (66 lb-ft)
14. 14

    Reinstall Valve Covers and Accessories
    Install new valve cover gaskets. Position valve covers and install bolts, tightening in proper sequence to specification. Reconnect PCV hoses and vacuum lines. Install ignition coils. Reinstall A/C compressor, alternator with bracket, and power steering pump. Reconnect all electrical connections using labels from disassembly.
15. 15

    Reinstall Remaining Components and Fill Fluids
    Reinstall thermostat housing with new O-ring. Reconnect all coolant hoses and heater hoses. Install serpentine belt. Install inner fender splash shield and wheel. Lower vehicle. Install new oil filter and fill engine with 6 quarts of Motorcraft 5W-20 oil. Fill cooling system with 13 quarts Motorcraft Orange coolant. Reconnect battery. Install engine cover.
    ℹ️Cooling system will require bleeding. Run engine and add coolant as level drops.

Reassembly

1. Torque all fasteners to specified values in proper sequence
2. Replace all gaskets and seals that were disturbed during disassembly
3. Use thread locker on fasteners as specified in service manual
4. Ensure all electrical connectors are fully seated and locked

Verification

• With engine cold, check oil level and adjust if necessary
• Check coolant level in reservoir and top off as needed
• Start engine and listen for abnormal timing chain noise (rattling or slapping sounds)
• Allow engine to reach operating temperature and verify no coolant or oil leaks from timing cover or valve covers
• Bleed cooling system by running engine with heater on high until thermostat opens, adding coolant as needed
• Check for diagnostic trouble codes related to camshaft position sensors
• Test drive vehicle and verify normal engine operation under load
• Recheck all fluid levels after test drive
• Monitor for leaks over next 100 miles of operation

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