Complete replacement of a single piston in the 3.5L EcoBoost V6 engine, requiring cylinder head removal, timing chain work, and engine disassembly.

Warnings

Tools required

Parts

• Piston assembly with pin and clips × 1 — Use OEM specification for 3.5L EcoBoost
• Piston ring set (standard or oversized as measured) × 1 — Use OEM specification
• Connecting rod bearing set × 1 — Use OEM specification
• Connecting rod bolts × 2 — TTY bolts - must replace
• Cylinder head gasket set × 1 — Use OEM MLS gasket
• Valve cover gaskets × 2 — Use OEM specification
• Timing chain cover gasket × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Oil filter × 1 — Motorcraft FL-910S or equivalent
• Oil drain plug crush washer × 1 — Use OEM specification
• Intake manifold gaskets × 1 — Use OEM specification
• Exhaust manifold gaskets × 1 — Use OEM specification
• Turbocharger gasket kit × 2 — Use OEM specification
• Coolant hoses (if damaged) × 1 — Inspect and replace as needed
• Various seals and O-rings × 1 — Complete gasket set recommended

Fluids

• Motorcraft 5W-20 Synthetic Blend engine oil — 6 qt
• Motorcraft Orange Coolant — 13 qt
• Assembly lube for bearings and piston — 0.25 qt

Preparation

1. Ensure vehicle is on level ground with wheels chocked and parking brake engaged
2. Disconnect negative battery cable and isolate from battery post
3. Remove engine cover and all plastic covers from engine bay
4. Drain engine coolant completely into appropriate container
5. Drain engine oil and remove oil filter
6. Relieve fuel system pressure by removing fuel pump fuse and cranking engine until it stalls
7. Remove air intake system including both turbocharger inlet tubes
8. Label and photograph all vacuum lines, electrical connectors, and hose routing before disconnection
9. Support engine from above with engine hoist or support fixture with load leveler
10. Remove front bumper cover for access to radiator and cooling system
11. Identify which cylinder requires piston replacement and plan access strategy

Procedure

1. 1

   Remove cooling system components
   Remove upper and lower radiator hoses, heater hoses, and all coolant lines connected to engine. Remove radiator and cooling fan assembly. Disconnect and remove charge air cooler and intercooler piping from both turbochargers. Remove coolant crossover tube between cylinder heads.
2. 2

   Remove fuel system and intake components
   Disconnect fuel lines at fuel rail (release residual pressure with shop towels ready). Remove throttle body and intake plenum assembly. Remove fuel rails with injectors attached (cap injectors to prevent contamination). Remove intake manifold by removing all mounting bolts and carefully lifting away. Label runner positions if servicing specific cylinder.
3. 3

   Remove exhaust and turbocharger assemblies
   Disconnect oxygen sensors and unbolt exhaust downpipes from both turbochargers. Remove oil feed and drain lines from turbochargers. Remove turbocharger mounting fasteners and remove both turbocharger assemblies with exhaust manifolds. This provides access to cylinder heads and timing components.
4. 4

   Remove valve covers and accessory drive
   Remove ignition coils and spark plugs from both banks. Unbolt and remove both valve covers with gaskets. Remove serpentine belt and all accessory drive components (alternator, A/C compressor, power steering pump). Remove crankshaft pulley using holding tool and breaker bar.
5. 5

   Remove timing chain cover and set timing marks
   Remove all timing chain cover bolts and carefully pry cover off (note dowel locations). Rotate crankshaft to TDC on cylinder #1 and verify all timing marks align properly on camshaft sprockets and crankshaft sprocket. Mark or photograph timing chain positions before removal. Install Ford timing chain locking tools to hold camshafts in position.
   ⚠Timing mark alignment is absolutely critical. Take multiple photos and verify TDC position before proceeding.
6. 6

   Remove timing chains and components
   Remove timing chain tensioners and guides. Remove camshaft sprocket bolts while holding camshafts with wrench on hex portion. Remove timing chains, crankshaft sprocket, and all chain guides. Keep left and right bank components separate and labeled.
7. 7

   Remove cylinder head
   Remove cylinder head bolts in reverse of tightening sequence (start from outside, work toward center). Use torque angle gauge marks to track bolt loosening. Carefully lift cylinder head off block using pry points only at designated locations. Remove and discard cylinder head gasket. Cover exposed cylinders with clean shop towels to prevent debris entry.
   ⚠Cylinder head is heavy and aluminum. Use proper lifting technique and avoid prying against sealing surfaces.
   Torque spec

   Cylinder Head Bolts65 Nm (48 lb-ft)
8. 8

   Remove oil pan and oil pickup
   Remove all oil pan bolts working from outside toward center. Carefully break oil pan gasket seal and lower pan away from engine. Remove oil pump pickup tube and screen assembly. This provides access to connecting rod caps from below.
   Torque spec

   Oil Pan Bolts12 Nm (9 lb-ft)
9. 9

   Inspect cylinder bore and remove ridge
   Inspect top of cylinder bore for ridge caused by ring wear. Use ridge reamer to carefully remove ridge at top of cylinder bore without removing excessive material. Clean all cuttings from cylinder. Measure cylinder bore diameter at multiple points using bore gauge to verify within specification (standard bore is 92.2-92.3mm). If taper or out-of-round exceeds 0.05mm, cylinder requires machining.
   ℹ️Ridge must be removed before piston extraction to prevent ring breakage and piston damage.
10. 10

    Remove piston and connecting rod assembly
    Rotate engine so target piston is at bottom dead center. Mark connecting rod and cap with cylinder number and orientation (mark faces toward front of engine). Remove connecting rod bolts and cap. Push piston and rod assembly up and out through top of cylinder bore. Keep cap with corresponding rod. Inspect rod journal on crankshaft for scoring or damage.
    ⚠Protect crankshaft journals from rod bolt contact. Install short lengths of vacuum hose over rod bolts during removal.
11. 11

    Disassemble and inspect old piston
    Remove piston rings using ring removal tool (expand only enough to slide off). Remove piston pin circlips and press out piston pin to separate piston from connecting rod. Inspect old piston for crack patterns, scoring, or damage to determine root cause of failure. Measure connecting rod for straightness and twist on rod checking fixture if available.
12. 12

    Prepare and install new piston
    Verify new piston matches specification and cylinder bore size. Install new piston pin into connecting rod small end with assembly lube. Install piston onto rod with directional arrow toward front of engine. Install new piston pin circlips ensuring they seat fully in grooves. Install piston rings using ring installation tool: oil control ring first (expander then rails), then second compression ring, then top compression ring. Verify all ring gaps are staggered 120 degrees apart and not aligned with pin.
    ⚠Piston rings are brittle and will break if overstretched. Use proper ring installation tool and expand only enough to fit over piston.
13. 13

    Install new connecting rod bearings
    Clean connecting rod and cap bearing surfaces thoroughly. Install new bearing inserts (upper and lower) ensuring bearing tang locks into rod and cap notches. Lubricate bearings heavily with assembly lube or engine oil. Measure bearing clearance using Plastigage if proper clearance verification is desired (spec: 0.025-0.058mm).
14. 14

    Install piston assembly into cylinder
    Lubricate cylinder bore with clean engine oil. Lubricate piston rings and piston skirt with assembly lube. Install piston ring compressor around piston and tighten firmly to compress all rings. Guide connecting rod through cylinder from top, carefully lowering piston into bore while keeping ring compressor flush with block deck. Tap piston gently with wooden hammer handle to seat into bore. Guide rod onto crankshaft journal from below.
    ⚠Ensure ring compressor is tight and square. Any ring protruding will catch on cylinder edge and break.
15. 15

    Install connecting rod cap and torque fasteners
    Install new connecting rod bolts into rod (TTY bolts must not be reused). Position rod cap onto rod with match marks aligned. Install new rod bolts and hand-tighten. Verify rod can move freely side-to-side on crankshaft journal. Torque connecting rod bolts to 45 Nm (33 lb-ft) in two stages (22 Nm first pass, 45 Nm second pass). Then rotate each bolt an additional 90 degrees using torque angle gauge. Verify rod still moves freely without binding after final torque.
    ⚠️Connecting rod bolts are TTY and MUST be new. Torque-plus-angle sequence must be followed exactly or rod will fail.
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
16. 16

    Verify piston installation and measurements
    Rotate crankshaft two complete revolutions by hand and verify smooth rotation with no binding. Piston should move freely through entire stroke. Use feeler gauge to verify connecting rod side clearance (spec: 0.15-0.30mm). Install dial indicator on piston crown and measure piston deck height (piston should be 0.3-0.5mm below deck at TDC).
17. 17

    Clean and prepare cylinder head and block surfaces
    Clean cylinder head and block mating surfaces thoroughly using gasket scraper and solvent. Remove all old gasket material and sealant. Clean bolt holes in block using bottoming tap or thread chaser. Blow out all bolt holes with compressed air. Inspect block deck surface for warpage using precision straightedge (maximum warp: 0.05mm). Verify all coolant and oil passages are clean and unobstructed.
18. 18

    Install cylinder head with new gasket
    Position new cylinder head gasket on block (verify correct orientation with alignment dowels and UP marking). Do not use any sealant on MLS gasket. Carefully lower cylinder head onto block, guiding over dowels. Install new cylinder head bolts finger-tight. Torque cylinder head bolts in proper sequence: First pass to 25 Nm, second pass to 65 Nm (48 lb-ft), then rotate all bolts 90 degrees, then rotate all bolts an additional 90 degrees (total 180 degrees angle). Follow Ford tightening sequence diagram exactly.
    ⚠️Cylinder head bolts are TTY. Tightening sequence and torque-plus-angle must be followed exactly. Incorrect torque will cause head gasket failure or bolt failure.
    Torque spec

    Cylinder Head Bolts65 Nm (48 lb-ft)
19. 19

    Install oil pan with new gasket
    Install new oil pan gasket (apply small bead of RTV sealant at front cover to block joints only). Position oil pan and install all bolts finger-tight. Torque oil pan bolts to 12 Nm (9 lb-ft) in star pattern from center outward. Install oil drain plug with new crush washer and torque to 35 Nm (26 lb-ft). Install oil pump pickup tube with new O-ring.
    Torque spec

    Oil Pan Bolts12 Nm (9 lb-ft)

    Oil Drain Plug35 Nm (26 lb-ft)
20. 20

    Reinstall timing components
    Install crankshaft sprocket and align timing mark. Position timing chains on crankshaft sprocket and verify slack is on tensioner side. Install camshaft sprockets with chains and align all timing marks per Ford specifications. Install chain guides and loosely install tensioners (do not release tensioner pins yet). Verify all timing marks align at TDC on cylinder #1. Install camshaft sprocket bolts and torque per specification. Release timing chain tensioners. Rotate crankshaft two full revolutions and verify all timing marks realign exactly.
    ⚠️Incorrect timing will cause catastrophic engine damage. Verify timing mark alignment at least three times before proceeding.
21. 21

    Install timing cover and remaining components
    Install new timing cover gasket and apply RTV sealant at oil pan to block joints. Install timing cover and torque all bolts to specification (various sizes). Install crankshaft pulley and torque center bolt per specification. Install valve covers with new gaskets and torque cover bolts to 19 Nm (14 lb-ft). Install all accessory drive components, serpentine belt, spark plugs, and ignition coils. Install intake manifold with new gaskets and torque gasket bolts to 23 Nm (17 lb-ft). Install fuel rails, throttle body, and all fuel system components. Install turbochargers with new gaskets and reconnect oil feed/drain lines. Install exhaust downpipes and oxygen sensors. Install cooling system components, charge air cooler, and all hoses. Install air intake system.
    Torque spec

    Cover Bolts19 Nm (14 lb-ft)

    Gasket Bolts23 Nm (17 lb-ft)
22. 22

    Refill fluids and perform initial start
    Install new oil filter and fill engine with 6 quarts of Motorcraft 5W-20 synthetic blend oil. Fill cooling system with 13 quarts Motorcraft Orange coolant (50/50 mix). Reconnect battery. Prime fuel system by cycling key to ON position three times without cranking. Perform initial engine start and verify oil pressure immediately. Allow engine to idle and monitor for any leaks, unusual noises, or warning lights. Bleed cooling system by running engine to operating temperature with heater on high.

Reassembly

1. Reassembly is integrated into main steps as this procedure requires complete disassembly and reassembly
2. Verify all electrical connectors are fully seated and locked
3. Verify all vacuum lines are connected per reference photos taken during disassembly
4. Double-check all fluid levels after initial warm-up cycle
5. Inspect entire engine bay for any tools or parts left behind before closing hood

Verification

• Start engine and verify immediate oil pressure on gauge (should show pressure within 2-3 seconds)
• Listen for any abnormal noises including knocking, ticking, or rattling that would indicate installation problems
• Monitor for any coolant, oil, or fuel leaks during initial warm-up period
• Verify no check engine lights or fault codes are present after warm-up
• Allow engine to reach full operating temperature and verify cooling fans cycle properly
• Perform test drive and monitor engine performance under light load and acceleration
• After first 50-100 miles, recheck all fluid levels and inspect for any leaks
• Consider changing oil and filter after 500 miles to remove any assembly debris or break-in particles
• Monitor oil consumption and engine performance over first 1000 miles to ensure proper piston sealing and break-in

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