Complete replacement of piston rings on all six cylinders of the 3.5L EcoBoost V6 engine, requiring engine removal, disassembly, cylinder honing, and precision reassembly.

Warnings

Tools required

Parts

• Complete piston ring set (6 cylinders) × 1 — Use OEM specification
• Cylinder head gasket set × 1 — Use OEM specification
• Oil pan gasket × 1 — Use OEM specification
• Valve cover gaskets × 2 — Use OEM specification
• Connecting rod bearing set (if reused, inspect carefully) × 1 — Use OEM specification
• Main bearing set (if needed) × 1 — Use OEM specification
• Engine oil filter × 1 — Motorcraft FL-910S or equivalent
• Oil drain plug crush washer × 1 — Use OEM specification
• RTV silicone sealant (oil-resistant) × 1 — Motorcraft TA-357 or equivalent
• Engine assembly lube × 1 — Use OEM specification
• Timing chain cover gasket × 1 — Use OEM specification
• Water pump gasket (if disturbed) × 1 — Use OEM specification

Fluids

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

Preparation

1. Park vehicle on level surface and engage parking brake
2. Disconnect negative battery terminal and wait 10 minutes for system discharge
3. Drain engine coolant completely into approved container
4. Drain engine oil and remove oil filter
5. Remove engine cover and front skid plate if equipped
6. Relieve fuel system pressure by removing fuel pump fuse and cranking engine until it stops
7. Position engine hoist and attach lifting straps to engine lift points
8. Support transmission with jack and remove transmission-to-engine bolts
9. Label and photograph all electrical connectors, vacuum lines, and hose routing before removal
10. Tag all exhaust, intake, turbo, and coolant connections for reassembly reference

Procedure

1. 1

   Remove engine from vehicle
   Disconnect all electrical connectors, coolant hoses, fuel lines (high and low pressure), vacuum lines, turbocharger intake/exhaust connections, transmission cooler lines, and motor mounts. Carefully lift engine from engine bay using hoist with load leveler. Immediately mount engine on engine stand using bellhousing bolt holes.
2. 2

   Remove external components
   Remove both turbochargers with all oil feed and return lines, exhaust manifolds, intake manifold, fuel rails and injectors, ignition coils and spark plugs, alternator, A/C compressor (leave hoses attached and secure aside), power steering pump bracket, valve covers, timing chain cover, and accessory drive components. Keep all fasteners organized by component.
   Torque spec

   Mounting Bolts54 Nm (40 lb-ft)
3. 3

   Remove cylinder heads
   Set engine to TDC on cylinder #1. Mark timing chain position on camshaft sprockets with paint. Remove timing chains, camshaft sprockets, and variable cam timing (VCT) components following Ford procedure. Remove cylinder head bolts in reverse of tightening sequence (consult service manual for exact sequence). Lift cylinder heads off and place on clean padded surface. Remove and discard head gaskets.
   Torque spec

   Cylinder Head Bolts65 Nm (48 lb-ft)
4. 4

   Remove oil pan and oil pump
   Remove oil pan bolts in reverse sequence and carefully separate oil pan from block. Remove oil pump pickup tube, then remove oil pump assembly. Inspect oil pump pickup screen for debris. Clean all gasket surfaces on block and oil pan thoroughly.
   Torque spec

   Oil Pan Bolts12 Nm (9 lb-ft)

   Oil Pump Pickup Tube12 Nm (9 lb-ft)
5. 5

   Remove ridge and inspect cylinders
   Use ridge reamer to carefully remove ridge at top of each cylinder bore where ring travel stops. Rotate crankshaft to position piston near bottom dead center before reaming. After ridge removal, inspect cylinders for scoring, taper, and out-of-round using dial bore gauge. Measure at multiple points. Cylinders must be within 0.002 inch specification. If excessive wear exists, engine requires machine shop boring.
   ⚠Do not allow ridge reamer cutting debris to fall into crankcase. Cover exposed areas with shop towels.
6. 6

   Remove pistons and connecting rods
   Mark each connecting rod and cap with cylinder number using permanent marker (1-6, front to rear). Note that EcoBoost connecting rods have orientation marks. Remove connecting rod bolts and carefully remove caps, keeping each cap with its original rod. Push piston and rod assembly up and out through top of cylinder. Install connecting rod cap back on rod immediately to prevent mixing. Place assemblies on clean work surface in cylinder order.
   ⚠Never mix connecting rod caps. Each cap is machined as a matched set with its rod.
   Torque spec

   Connecting Rod Bolts45 Nm (33 lb-ft)
7. 7

   Remove old piston rings
   Using piston ring expander tool, carefully remove all three rings from each piston (two compression rings and one oil control ring assembly). Inspect ring grooves for carbon buildup, cracking, or wear. Clean ring grooves thoroughly with ring groove cleaner or broken piece of old ring. Inspect pistons for cracks, especially around pin bosses and ring lands. Check piston-to-bore clearance specifications.
   ⚠Piston rings are brittle and sharp. Expand only enough to remove without excessive force.
8. 8

   Hone cylinders
   Using cylinder hone with 240-280 grit stones, hone each cylinder bore to create proper crosshatch pattern (45-60 degree angle). Continuously move hone up and down while rotating to avoid creating grooves. Honing removes glaze and creates microscopic grooves for oil retention. After honing, wash cylinders thoroughly with hot soapy water and scrub brush. Dry immediately and apply light coat of clean engine oil to prevent rust. Final cleaning with brake cleaner and lint-free cloths is critical - no honing debris can remain.
   ℹ️Proper crosshatch pattern is essential for ring break-in. Too smooth and rings won't seat; too rough and rings wear prematurely.
9. 9

   Measure and fit new piston rings
   For each cylinder, insert top compression ring (without piston) into bore and push down with piston crown to square it about 0.5 inch from top. Measure ring end gap with feeler gauge. Gap should be 0.010-0.020 inch (verify specification in service manual). Repeat for second compression ring and oil control ring rails. If gap is too tight, carefully file ring ends square. Record all measurements. Test-fit each ring in its groove on piston - ring should move freely without binding but have minimal side clearance.
   ⚠Ring end gap too small will cause ring butting and cylinder scoring when engine heats up. Too large allows excessive blowby.
10. 10

    Install new piston rings
    Using ring expander tool, install oil control ring first: install lower rail, then expander/spacer, then upper rail. Ensure expander ends do not overlap. Install second (middle) compression ring with identification mark facing up. Install top compression ring with mark facing up. Stagger ring end gaps 120 degrees apart, ensuring no gaps align with piston pin. Oil ring rail gaps should be opposite each other and opposite compression ring gaps. Double-check all rings rotate freely in grooves.
    ⚠Ring orientation is critical. Installing rings upside-down will cause immediate engine failure and oil consumption.
11. 11

    Prepare crankshaft and main bearings
    Inspect all main bearing journals for scoring or damage. Measure journals with micrometer and compare to specification. Clean all oil passages in crankshaft with rifle brush and compressed air. If reusing main bearings, inspect carefully for wear, scoring, or fatigue. Install main bearings in block and caps (do not mix caps). Apply thin coat of assembly lube to bearing surfaces. Carefully lower crankshaft into position.
    ℹ️Main bearing caps on EcoBoost engines are numbered and have specific orientation. Consult service manual for proper sequence.
    Torque spec

    Main Bearing Cap Bolts75 Nm (55 lb-ft)
12. 12

    Install pistons into cylinders
    Inspect connecting rod bearings and replace if any wear is visible. Install bearings in rods and caps with tabs properly seated. Apply assembly lube to bearings, piston skirts, rings, and cylinder walls. Position ring compressor on piston and tighten firmly. Ensure ring end gaps remain properly staggered. Insert connecting rod into cylinder with orientation mark facing front of engine. Gently tap piston crown with wooden or plastic hammer handle while guiding rod onto journal. Install rod cap in correct orientation and hand-start bolts.
    ⚠Never force piston into bore. If excessive resistance is felt, remove and check for ring protruding from compressor.
13. 13

    Torque connecting rod bolts
    Torque connecting rod bolts to 45 Nm (33 ft-lb) using torque wrench, then tighten an additional angle as specified in service manual (typically 90 degrees). Use torque angle gauge for precise angle measurement. After torquing, verify crankshaft rotates freely by hand. Check each rod for side clearance (0.004-0.010 inch typical). Repeat for all six connecting rods.
    ⚠Connecting rod bolts are TTY and must be replaced with new bolts. Never reuse torque-to-yield fasteners.
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
14. 14

    Install oil pump and oil pan
    Install oil pump assembly and torque mounting bolts. Install oil pump pickup tube with new O-ring and torque to specification. Apply thin bead of RTV sealant to oil pan mating surface where timing cover meets block. Install new oil pan gasket, position oil pan, and install bolts finger-tight. Torque oil pan bolts in sequence from center outward to 12 Nm (9 ft-lb). Allow RTV to cure per manufacturer instructions before filling with oil.
    Torque spec

    Oil Pan Bolts12 Nm (9 lb-ft)

    Oil Pump Pickup Tube12 Nm (9 lb-ft)

    Mounting Bolts54 Nm (40 lb-ft)
15. 15

    Install cylinder heads and timing components
    Install new head gaskets on block with orientation marks facing up. Carefully lower cylinder heads into position ensuring gaskets remain aligned. Install new cylinder head bolts and torque in proper sequence: first pass to 65 Nm (48 ft-lb), then tighten specified angle (typically 90 degrees, then additional 90 degrees - verify in service manual). Install timing chains, VCT components, and camshaft sprockets, aligning timing marks precisely. Install timing chain cover with new gasket and torque bolts.
    ⚠️Incorrect valve timing will cause catastrophic engine damage. Verify timing marks multiple times before final assembly.
    Torque spec

    Cylinder Head Bolts65 Nm (48 lb-ft)

    Gasket Bolts23 Nm (17 lb-ft)
16. 16

    Complete engine reassembly and installation
    Install valve covers with new gaskets and torque bolts. Reinstall all external components in reverse order of removal: accessory drive components, alternator, A/C compressor, power steering pump, fuel rails and injectors, intake manifold, exhaust manifolds, and both turbochargers with all oil and coolant lines. Verify all electrical connectors are secured. Remove engine from stand and install in vehicle. Connect motor mounts, transmission, all hoses, lines, and electrical connections. Install new oil filter and drain plug with new crush washer.
    Torque spec

    Oil Drain Plug35 Nm (26 lb-ft)

    Mounting Bolts54 Nm (40 lb-ft)

    Gasket Surface Bolts23 Nm (17 lb-ft)

Reassembly

1. Fill engine with 6.0 quarts of Motorcraft 0W-20 full synthetic oil
2. Fill cooling system with 13.0 quarts of Motorcraft Orange coolant and bleed air from system
3. Reconnect battery negative terminal
4. Prime oil system by cranking engine with fuel pump fuse removed and spark plugs out for 10 seconds, wait 30 seconds, repeat 3 times
5. Reinstall spark plugs and ignition coils with proper torque
6. Double-check all fluid levels, hose connections, and electrical connectors before starting

Verification

• Install fuel pump fuse and start engine. Engine should start within 5 seconds. Monitor oil pressure immediately - should reach 25+ psi within 2 seconds
• Allow engine to idle for 20 minutes while monitoring for leaks, unusual noises, or warning lights. Oil pressure should stabilize at 35-60 psi at operating temperature
• Check for coolant, oil, and fuel leaks around all connections, gaskets, and sealing surfaces
• Verify smooth idle with no misfires or excessive vibration. Check for exhaust leaks at manifold connections
• Perform gentle test drive avoiding heavy acceleration or loads for first 500 miles to allow rings to properly seat
• After 30 minutes of operation, recheck all fluid levels and inspect for any new leaks
• Change oil and filter at 500 miles, then follow normal service intervals
• Monitor oil consumption for first 2000 miles - rings should be fully seated by then with no abnormal consumption

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