This procedure covers replacement of a single piston in the 3.5L EcoBoost V6 engine, requiring removal of the cylinder head, oil pan, and connecting rod assembly to access the damaged piston.

Warnings

Tools required

Parts

• Piston with pin and clips × 1 — Use OEM specification - must match compression ratio
• Piston ring set (for single cylinder) × 1 — Use OEM specification
• Connecting rod bearings (standard or appropriate oversize) × 1 — Use OEM specification
• Cylinder head gasket × 1 — Use OEM MLS gasket
• Cylinder head bolts (TTY) × 1 — Use OEM - not reusable
• Connecting rod bolts (TTY) × 2 — Use OEM - not reusable
• Oil pan gasket × 1 — Use OEM specification
• Valve cover gasket (affected bank) × 1 — Use OEM specification
• Timing cover gasket × 1 — Use OEM specification
• Oil filter × 1 — Motorcraft FL-910S or equivalent
• Oil drain plug crush washer × 1 — Use OEM specification
• Turbocharger gaskets (if removed) × 1 — Use OEM specification
• Intake manifold gaskets × 1 — Use OEM specification
• Exhaust manifold gaskets × 1 — Use OEM specification

Fluids

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

Preparation

1. Identify which cylinder requires piston replacement and whether it is in the front (passenger side) or rear (driver side) bank
2. Disconnect negative battery cable and wait 10 minutes for airbag system to discharge
3. Remove engine cover and note routing of all vacuum lines, wiring harnesses, and fuel lines with photos
4. Relieve fuel system pressure: remove fuel pump fuse, start engine and let it stall, attempt restart to confirm pressure relief
5. Drain engine coolant completely into appropriate container by opening radiator petcock and lower radiator hose
6. Drain engine oil and remove oil filter
7. Remove front wheels and raise vehicle on lift or support with jack stands at manufacturer-specified lift points
8. Remove lower splash shields and undertray panels for access to oil pan and front of engine
9. Support engine with hoist or support fixture from above before removing any mounts
10. Clean engine exterior thoroughly to prevent contamination during disassembly

Procedure

1. 1

   Remove intake and charge air system
   Disconnect air intake tube from throttle body. Remove charge air cooler (intercooler) tubes from both turbochargers and throttle body. Remove intake manifold by disconnecting fuel rail, vacuum lines, PCV connections, and electrical connectors. Remove manifold mounting bolts and lift manifold away. Cap all open ports to prevent debris entry.
2. 2

   Remove turbocharger and exhaust components (affected side)
   Disconnect oxygen sensor connectors. Remove exhaust downpipe heat shields. Unbolt exhaust manifold from cylinder head (6 bolts). If replacing piston on rear bank, remove or lower the affected turbocharger for clearance. Support turbocharger with wire if not fully removing. Keep all hardware organized by location.
   ⚠Exhaust studs are prone to breakage. Apply penetrating oil 24 hours before removal if possible. Use a 6-point socket and avoid impact tools on studs.
3. 3

   Remove valve cover and timing components
   Remove ignition coils and spark plugs from affected bank. Remove valve cover from the affected cylinder bank. Rotate engine to TDM on cylinder #1 and lock timing using manufacturer-specified tools. Remove accessory drive belt. Remove timing chain cover (front cover) by removing all perimeter bolts. Note the locations of different length bolts. Remove timing chain tensioner, then timing chain guide. Carefully remove timing chain from camshaft sprockets while supporting chain to prevent it from falling into crankcase.
   ⚠Do not allow timing chain to fall into engine. Use wire or zip ties to support chain once removed from sprockets.
   Torque spec

   Cover Bolts19 Nm (14 lb-ft)
4. 4

   Remove cylinder head
   Disconnect all remaining electrical connectors from cylinder head including camshaft position sensors and variable valve timing solenoids. Remove camshaft caps in reverse order of tightening sequence (outside to inside in multiple passes). Lift camshafts out carefully and store in clean area. Remove cylinder head bolts in reverse of tightening sequence using multiple passes to prevent warping. Lift cylinder head off block using appropriate lifting points. Do not pry between head and block. Place cylinder head on padded work surface with combustion chambers facing up.
   ⚠Cylinder head is extremely heavy (approximately 60 lbs). Use proper lifting technique or get assistance to avoid injury or dropping the head.
   Torque spec

   Cylinder Head Bolts65 Nm (48 lb-ft)

   Sensor Bolts12 Nm (9 lb-ft)

   Electrical Connector Bolts8 Nm (6 lb-ft)
5. 5

   Remove oil pan and oil pump pickup
   Remove all oil pan bolts in a crisscross pattern starting from the outside edges. Carefully separate oil pan from block using a plastic gasket scraper - do not pry with metal tools that could damage sealing surfaces. Remove oil pump pickup tube mounting bolts and lower pickup tube out through oil pan opening.
   ℹ️Oil pan sealing surface on aluminum block is easily damaged. Use only plastic scrapers and avoid metal tools.
   Torque spec

   Oil Pan Bolts12 Nm (9 lb-ft)
6. 6

   Remove cylinder ridge and prepare for piston removal
   Rotate crankshaft to bring the affected piston to bottom dead center (BDC). Using a ridge reamer, carefully remove any carbon ridge at the top of the cylinder bore. Work slowly and ensure reamer does not cut into cylinder wall below the ridge. Vacuum out all carbon and aluminum debris. Stuff clean shop rags into adjacent cylinders to prevent debris contamination.
   ⚠Failure to remove cylinder ridge before piston removal can break piston rings or damage piston ring lands.
7. 7

   Remove connecting rod and piston assembly
   Mark the connecting rod cap and rod with the cylinder number using a permanent marker or stamping tool. Remove connecting rod cap bolts and discard (TTY bolts are not reusable). Remove rod cap and set aside with correct orientation marked. Push piston and connecting rod assembly up and out through the top of the cylinder bore. Be careful not to nick the crankshaft journal with the rod bolts - cover rod bolts with rubber hose or old spark plug boots. Place assembly on clean work surface.
   ⚠Rod bolts can scratch or gouge crankshaft journals if contact is made. A damaged journal will require crankshaft machining or replacement.
   Torque spec

   Connecting Rod Bolts45 Nm (33 lb-ft)
8. 8

   Inspect cylinder bore and crankshaft
   Using a cylinder bore gauge or telescoping gauge and micrometer, measure cylinder bore at top, middle, and bottom in both parallel and perpendicular orientations to crankshaft. Record all measurements. Maximum taper is 0.002 inches, maximum out-of-round is 0.002 inches. If bore exceeds specifications, cylinder must be honed or bored to next oversize. Inspect crankshaft journal for scoring, measure with micrometer, and check for proper oil clearance with bearing installed using Plastigage if desired. Standard bearing clearance is 0.0011-0.0018 inches.
   ℹ️If cylinder bore is excessively worn, tapered, or out-of-round beyond specifications, boring to 0.010 or 0.020 oversize may be required with corresponding oversize pistons.
9. 9

   Disassemble old piston and prepare new piston
   Remove piston rings from old piston using ring expander tool, starting with oil control ring then compression rings. Note orientation and position of each ring. Remove piston pin retaining clips and press or tap out piston pin to separate piston from connecting rod. Keep connecting rod for reuse. Install new connecting rod bearings in rod and cap, ensuring locating tabs are properly seated. Verify new piston weight matches old piston (within 2 grams). Install piston pin in new piston and connecting rod, ensuring pin moves freely but without excessive play. Install new piston pin retaining clips ensuring they are fully seated in grooves.
   ⚠Piston pin clips must be fully seated in their grooves. A loose clip can fall out and cause catastrophic engine damage.
10. 10

    Install piston rings
    Install piston rings starting with oil control ring (bottom): first install expander ring, then lower and upper oil control rails with gaps positioned 180 degrees apart. Install lower compression ring (second ring) with identification mark facing up and gap positioned 180 degrees from oil ring gaps. Install upper compression ring (top ring) with identification mark facing up and gap positioned 180 degrees from second ring gap. Verify all ring end gaps are within specification (typically 0.006-0.012 inches for this engine) using feeler gauge with ring positioned in cylinder bore. If gaps are tight, carefully file ring ends using ring filer.
    ⚠Ring orientation is critical. Installing rings upside down will cause excessive oil consumption and poor sealing. Verify manufacturer markings face upward.
11. 11

    Install piston and connecting rod assembly
    Lubricate cylinder bore, piston, rings, and connecting rod bearings with clean engine oil. Stagger ring gaps approximately 120 degrees apart around piston. Position piston so any directional marking (usually an arrow or FRONT mark) faces toward front of engine. Cover rod bolts with rubber hose. Install piston ring compressor and tighten evenly around piston. Insert assembly into cylinder bore from top, guiding connecting rod carefully. Tap piston gently through ring compressor into bore using wooden hammer handle or plastic mallet. Once piston crown is flush with block deck, remove ring compressor and push piston down until connecting rod reaches crankshaft journal.
    ⚠Never force piston into bore. If excessive resistance is felt, remove piston and verify ring compressor is properly positioned and rings are not caught.
12. 12

    Install connecting rod cap and torque
    Verify connecting rod bearing is properly seated in rod and cap with locating tabs engaged. Lubricate crankshaft journal, rod bolts, and bearing surfaces with engine oil. Position connecting rod over crankshaft journal and install rod cap in correct orientation (markings on rod and cap must be on same side and match cylinder number). Install new connecting rod bolts finger tight. Using torque wrench, torque bolts to 45 Nm (33 lb-ft). Then rotate each bolt an additional 90 degrees using angle gauge. Verify rod has proper side clearance on crankshaft (0.006-0.014 inches) and rotates freely without binding.
    ⚠TTY connecting rod bolts must be torqued to specification plus angle. Do not reuse old bolts or skip the angle portion of the torque sequence.
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
13. 13

    Clean all mating surfaces and install oil pan
    Remove all old gasket material from engine block and oil pan using plastic scraper. Clean surfaces with brake cleaner and lint-free cloth. Inspect oil pan for cracks or damage. Install new oil pan gasket - some gaskets use RTV sealant, others are pre-formed. If using RTV, apply continuous 3mm bead to oil pan flange. Install oil pump pickup tube with new O-ring. Position oil pan on block and install all bolts finger tight. Torque oil pan bolts in crisscross pattern from center outward to specification.
    Torque spec

    Oil Pan Bolts12 Nm (9 lb-ft)

    Gasket Surface Bolts23 Nm (17 lb-ft)
14. 14

    Install cylinder head with new gasket
    Verify cylinder head mating surface and block deck are completely clean and free of debris. Install new cylinder head gasket with orientation marks (UP or TOP) facing up and FRONT toward front of engine. Carefully lower cylinder head onto block, aligning dowel pins. Install new cylinder head bolts (TTY - do not reuse) and hand tighten in sequence from center outward. Following Ford tightening sequence, torque all bolts to 65 Nm (48 lb-ft) in sequence. Then torque all bolts an additional 90 degrees in sequence. Finally torque all bolts a final 90 degrees in sequence (total 180 degrees of rotation after initial torque).
    ⚠Cylinder head bolt sequence and torque-plus-angle procedure is critical. Failure to follow exact sequence or angles will result in head gasket failure.
    Torque spec

    Cylinder Head Bolts65 Nm (48 lb-ft)
15. 15

    Reinstall timing components and valve train
    Lubricate camshaft journals and lobes with engine assembly lube. Install camshafts in correct positions (intake and exhaust) with timing marks aligned. Install camshaft caps in correct positions following numbered sequence, torquing progressively in multiple passes. Reinstall timing chain over camshaft sprockets while maintaining proper timing alignment. Install timing chain guide and tensioner. Verify timing marks are correctly aligned before proceeding. Install timing cover with new gasket, torquing cover bolts to specification. Rotate engine two complete revolutions by hand and recheck timing alignment.
    ⚠️Incorrect cam timing will cause valve-to-piston contact and catastrophic engine damage when engine is started. Triple-check all timing marks before buttoning up engine.
    Torque spec

    Cover Bolts19 Nm (14 lb-ft)

    Mounting Bolts55 Nm (40 lb-ft)
16. 16

    Complete final assembly
    Install valve cover with new gasket. Install spark plugs to specification (typically hand tight plus 1/4 turn for new plugs). Install ignition coils. Reinstall intake manifold with new gaskets, torquing bolts in sequence. Reconnect fuel rail, vacuum lines, PCV system, and all electrical connectors. Reinstall turbocharger and exhaust components with new gaskets. Reinstall charge air cooler tubes and air intake system. Install new oil filter and install oil drain plug with new crush washer. Reinstall all shields and undertrays.
    Torque spec

    Oil Drain Plug35 Nm (26 lb-ft)

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

    Fill fluids and prime engine
    Fill engine with 6 quarts of Motorcraft 0W-20 full synthetic engine oil. Refill cooling system with 13 quarts of Motorcraft Orange coolant mixture. Reconnect battery. Turn ignition to ON position (do not start) for 30 seconds to allow fuel pump to prime fuel system. Repeat 3 times. Disable ignition system by disconnecting coil packs, then crank engine for 10-15 seconds to build oil pressure and prime lubrication system. Reconnect coil packs.

Reassembly

1. All removed components should be reinstalled in reverse order of removal
2. Replace all single-use gaskets, seals, and TTY fasteners - never reuse these components
3. Apply thread sealant or anti-seize only where specified by manufacturer
4. Route all wiring harnesses, vacuum lines, and fuel lines exactly as documented during disassembly
5. Verify all electrical connectors are fully seated with locking tabs engaged
6. Double-check that no tools, rags, or parts have been left in engine compartment before starting

Verification

• Check that engine oil level is at full mark on dipstick after allowing engine to sit for 5 minutes
• Verify coolant level is correct in overflow tank and no air pockets remain in system
• Start engine and verify immediate oil pressure indication on gauge or warning light extinguishes within 2-3 seconds
• Allow engine to idle and monitor for any unusual noises, vibrations, or knocking sounds from repaired cylinder
• Check for oil leaks at oil pan gasket, timing cover, and valve cover while engine is running
• Check for coolant leaks at cylinder head gasket and all cooling system connections
• Check for fuel leaks at all fuel system connections
• Verify no exhaust leaks at manifold or turbocharger connections
• Allow engine to reach normal operating temperature and verify cooling fans cycle properly
• Perform a test drive monitoring for proper power delivery, smooth operation, and no warning lights
• After test drive, recheck all fluid levels and inspect for any new leaks
• Use scan tool to verify no diagnostic trouble codes are present
• Monitor engine oil consumption over first 500 miles - rings require break-in period

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