Timing Chain Tensioner

This procedure replaces the timing chain tensioners on the 3.5L EcoBoost V6 engine, requiring removal of the front timing cover and synchronization of camshaft and crankshaft timing.

Warnings

Tools required

Parts

• Timing chain tensioner kit (includes both primary and secondary tensioners) × 1 — Motorcraft timing chain tensioner kit for 3.5L EcoBoost
• Timing cover gasket × 1 — Use OEM specification
• Valve cover gaskets (left and right) × 2 — Use OEM specification
• Crankshaft front seal × 1 — Use OEM specification
• RTV silicone gasket maker (Motorcraft TA-31) × 1 — Motorcraft TA-31 or equivalent
• Engine oil and filter × 1 — Use OEM specification

Fluids

• Motorcraft 5W-20 Synthetic Blend — 6 qt
• Motorcraft Orange Coolant — 2 qt

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery cable and wait 10 minutes for capacitive discharge
3. Allow engine to reach full operating temperature, then shut off and cool for 30 minutes
4. Remove engine cover and air intake system
5. Drain engine coolant into appropriate container using radiator petcock and lower hose
6. Drain engine oil completely and remove oil filter
7. Remove front wheels and raise vehicle on jack stands
8. Remove lower splash shields and front skid plate if equipped
9. Support engine from above using support bar across strut towers or from below with transmission jack
10. Document all timing mark positions with photographs for reference during reassembly

Procedure

1. 1

   Remove accessory drive system
   Remove the serpentine belt by rotating the tensioner clockwise. Remove the belt tensioner assembly. Remove the power steering pump and position aside without disconnecting hydraulic lines. Remove the A/C compressor and position aside without disconnecting refrigerant lines. Support both components with wire or straps to prevent strain on hoses.
2. 2

   Remove valve covers
   Disconnect ignition coils and fuel injector electrical connectors on both banks. Remove ignition coils from all six cylinders. Disconnect PCV hoses and vacuum lines from valve covers. Remove valve cover bolts in reverse of tightening sequence. Carefully lift off both valve covers and inspect gaskets. Clean all gasket surfaces thoroughly with gasket scraper, ensuring no debris falls into engine.
3. 3

   Remove front engine mount and crankshaft pulley
   Remove the right-hand engine mount (passenger side) and mount bracket to allow engine to be lowered slightly for timing cover access. Using the crankshaft damper holding tool, prevent crankshaft rotation and remove the crankshaft pulley bolt. Use a harmonic balancer puller to remove the crankshaft pulley from the crankshaft snout. Inspect keyway for damage.
4. 4

   Remove timing cover
   Disconnect coolant hoses from timing cover and water pump. Remove all timing cover bolts, noting the location of different length bolts and 8mm vs. standard bolts. Carefully pry timing cover away from engine block using plastic pry tools at designated pry points. Remove timing cover and gasket. Clean all sealing surfaces with RTV remover and gasket scraper. Inspect water pump condition while accessible.
5. 5

   Verify and lock engine timing position
   Rotate crankshaft clockwise (viewing from front) until cylinder 1 is at TDC on compression stroke. Install camshaft alignment pins through designated holes in rear of both cylinder heads to lock all four camshafts in position. Verify timing marks on crankshaft sprocket align with marks on engine block. Verify all camshaft sprocket timing marks align with cylinder head marks. Take detailed photographs of all timing relationships.
   ⚠️Do not proceed unless all timing marks are perfectly aligned and camshaft locking pins are fully seated. Incorrect timing will destroy the engine.
6. 6

   Remove timing chain tensioners and guides
   Remove the timing chain tensioner bolts on both primary timing chains (left and right). The tensioners are spring-loaded; control removal carefully. Remove secondary chain tensioners for the variable camshaft timing (VCT) system. Remove timing chain guide bolts and guides. Mark all components for position reference. Inspect timing chain wear by measuring slack and checking for elongation. If chains show wear beyond specification (more than 1/4 inch deflection), chains should also be replaced.
   ⚠Timing chain tensioners are under spring pressure. Control removal to prevent dropping or injury.
7. 7

   Inspect timing system components
   With tensioners removed, inspect all timing chain guide surfaces for wear grooves or damage. Check VCT phasers for free play or damage. Inspect all sprockets for wear on teeth. Verify crankshaft and camshaft sprockets have no play on their mounting surfaces. Check timing chains for side plate wear or stretched links. Any worn components must be replaced before reassembly.
8. 8

   Install new timing chain guides
   Install new or inspected timing chain guides in their original positions. Ensure guides are properly seated in mounting bosses. Install guide bolts and torque to specification. Verify guides do not interfere with chain travel and are positioned correctly relative to sprockets.
9. 9

   Prepare and install new tensioners
   Remove new tensioners from packaging. Compress each tensioner using a vise or tensioner compression tool until the locking pin or clip can be installed to hold it in compressed position. Verify each tensioner is fully compressed and locked before installation. Install tensioners in their respective positions with locking pins still in place. Install tensioner bolts and torque to specification.
   ⚠Tensioners must remain locked in compressed position with pins installed until timing cover is completely reinstalled. Premature release will make timing cover installation impossible.
10. 10

    Verify timing alignment before cover installation
    Double-check that all camshaft locking pins are still fully seated. Verify crankshaft timing mark alignment has not shifted. Manually rotate each timing chain to ensure proper tension and guide engagement. Verify VCT phasers are in correct positions. Do not proceed until all timing relationships are confirmed correct.
    ⚠️This is the final verification point before sealing the engine. Any misalignment must be corrected now.
11. 11

    Install timing cover with new gasket
    Install new crankshaft front seal into timing cover using seal driver. Apply small bead of RTV silicone (Motorcraft TA-31) to specified areas where timing cover meets cylinder head-to-block mating surfaces. Install new timing cover gasket. Carefully position timing cover onto engine, ensuring it does not disturb timing components. Install all timing cover bolts hand-tight initially. Torque 8mm bolts in specified sequence first, then torque remaining bolts in sequence.
12. 12

    Release timing tensioners
    Access tensioner lock pin locations through timing cover access holes or ports. Carefully remove locking pins from all tensioners using needle-nose pliers or appropriate tool. Verify tensioners extend and apply proper tension to chains. Listen for audible click as tensioners engage. This confirms proper tensioner function.
    ℹ️Once tensioner pins are removed, do not rotate crankshaft until camshaft locking pins are removed or engine damage will occur.
13. 13

    Remove camshaft locking pins and verify rotation
    Carefully remove all camshaft alignment/locking pins from cylinder heads. Store pins in tool kit for future use. Slowly rotate crankshaft two complete revolutions clockwise by hand using socket on crankshaft bolt. Feel for any resistance or binding. Reinstall camshaft locking pins to verify timing has maintained correct alignment after rotation. All pins should insert freely if timing is correct. Remove pins again after verification.
    ⚠️If any resistance is felt during rotation or timing pins do not align after two rotations, stop immediately and diagnose timing error before proceeding.
14. 14

    Install crankshaft pulley and accessory components
    Clean crankshaft snout and pulley mounting surface. Install crankshaft pulley onto crankshaft, ensuring keyway is properly aligned. Install new crankshaft pulley bolt. Using crankshaft holding tool, torque bolt to specification. Reinstall right-hand engine mount and bracket. Install A/C compressor and power steering pump to their mounting brackets. Install belt tensioner assembly. Install serpentine belt following routing diagram.
15. 15

    Install valve covers and complete reassembly
    Install new valve cover gaskets onto valve covers. Apply small amount of RTV sealant at camshaft cap-to-cylinder head corners as specified. Position valve covers onto cylinder heads. Install valve cover bolts and torque in proper sequence from center outward. Reconnect all ignition coil and injector electrical connectors. Install ignition coils. Reconnect PCV hoses and vacuum lines. Reinstall air intake system and engine cover. Reinstall front skid plate, splash shields, and wheels.

Reassembly

1. Refill engine with 6 quarts of Motorcraft 5W-20 synthetic blend oil and install new oil filter
2. Refill cooling system with Motorcraft Orange coolant mixture to proper level
3. Reconnect negative battery cable
4. Prime fuel system by cycling ignition on and off three times without cranking
5. Verify all electrical connections are secure and all tools are removed from engine bay

Verification

• Start engine and verify immediate oil pressure on gauge within 3 seconds
• Listen for any abnormal timing chain noise, rattling, or knocking during startup and idle
• Verify no coolant or oil leaks from timing cover, valve covers, or crankshaft seal
• Allow engine to reach operating temperature and verify smooth idle with no misfires
• Perform test drive and verify normal engine performance under load and acceleration
• Recheck timing cover and valve cover areas for leaks after test drive
• Scan for diagnostic trouble codes using OBD-II scanner to verify VCT system operation
• After 50-100 miles, recheck oil level and inspect for any new leaks

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