Piston - Single

Complete single piston replacement on a 2009 Aston Martin DB9 6.0L V12, requiring engine removal, cylinder head removal, crankshaft service, and piston assembly installation with torque-to-yield fasteners.

Warnings

Tools required

Parts

• Piston assembly with rings and pin × 1 — Use OEM specification - grade matched to existing pistons
• Connecting rod bearing set (upper and lower) × 1 — Use OEM specification - check bearing code
• Connecting rod bolts × 2 — TTY fasteners - must replace
• Cylinder head gasket set (affected bank) × 1 — Use OEM specification
• Valve cover gasket set × 1 — Use OEM specification
• Intake manifold gasket set × 1 — Use OEM specification
• Exhaust manifold gaskets (affected bank) × 1 — Use OEM specification
• Engine oil filter × 1 — Use OEM specification
• Oil drain plug crush washer × 1 — Copper or aluminum
• Coolant (OAT 50/50 premixed) × 1 — OEM approved ethylene glycol OAT
• Engine oil (5W-30) × 1 — OEM approved synthetic
• Oil pan gasket × 1 — Use OEM specification
• Timing chain cover gasket × 1 — Use OEM specification
• Crankshaft front seal × 1 — Use OEM specification
• Water pump gasket or O-ring set × 1 — Use OEM specification
• Throttle body gaskets × 2 — Use OEM specification
• Fuel injector O-ring kit × 1 — Use OEM specification

Fluids

• 5W-30 synthetic engine oil — 10.5 qt
• OAT 50/50 coolant premix — 10.5 qt
• Touchtronic 6-speed ZF ATF — 0.5 qt

Preparation

1. Park vehicle on level surface and engage parking brake. Place wheel chocks at rear wheels.
2. Disconnect negative battery cable, then positive cable. Remove battery from engine bay.
3. Allow engine to cool completely for minimum 4 hours if recently operated.
4. Relieve fuel system pressure by removing fuel pump fuse and cranking engine until it stalls, then crank for additional 5 seconds.
5. Recover AC refrigerant using certified recovery machine. Cap all AC line fittings immediately after disconnection.
6. Drain engine coolant completely from radiator petcock and engine block drain plugs into appropriate container.
7. Drain engine oil from drain plug and remove oil filter. Dispose of fluids per local regulations.
8. Remove engine cover panels and undertray. Remove front bumper cover for radiator access.
9. Position drain pans and prepare clean workspace for engine removal. Clear minimum 4 feet overhead for hoist operation.

Procedure

1. 1

   Remove Front End Components and Cooling System
   Remove upper radiator crossmember support and hood latch assembly. Disconnect radiator hoses, transmission cooler lines, and oil cooler lines at radiator. Remove radiator cooling fans as assembly (electrical connectors on fan shroud). Remove radiator and condenser assembly forward out of vehicle. Disconnect heater hoses at firewall bulkhead. Remove accessory drive belts by releasing automatic tensioners. Cap all open coolant and oil line fittings to prevent contamination.
2. 2

   Disconnect Engine Electrical and Fuel Systems
   Disconnect both main engine harness connectors at firewall pass-through (large multi-pin connectors). Disconnect alternator, starter motor, and ground strap connections. Label and disconnect all ignition coil connectors (verify exact coil count against OEM documentation - typically one coil per cylinder on this engine). Disconnect throttle body connectors on both banks. Disconnect fuel supply and return lines at fuel rail using appropriate disconnect tools - be prepared for residual fuel spillage. Disconnect evaporative emissions lines and brake booster vacuum line. Disconnect air mass/airflow sensor(s), coolant temperature sensors, and oil pressure sender (verify sensor types against OEM documentation).
3. 3

   Remove Intake and Exhaust Systems
   Remove engine acoustic cover and throttle body intake tubes. Disconnect PCV hoses and crankcase ventilation lines. Remove intake manifold assembly - this is a multi-piece aluminum casting spanning both banks with approximately 18-22 mounting fasteners (primarily Torx). Disconnect exhaust downpipes from manifolds at flanges (spring-loaded joints with approximately 3 nuts per side). Remove heat shields from exhaust manifolds if present. On affected bank only, remove exhaust manifold(s) from cylinder head (verify exact fastener count against OEM documentation).
4. 4

   Disconnect Transmission and Remove Engine Mounts
   Support the torque tube/transaxle appropriately. Remove the driveplate access cover. Mark the engine driveplate/coupling to torque tube relationship. Remove the engine-to-torque-tube coupling fasteners (verify exact count against OEM documentation). Separate the torque tube from the engine rear flange (verify fastener count and locations against OEM documentation). Disconnect any wiring at the torque tube/engine rear interface as required for engine separation (transaxle remains in vehicle). Remove left and right engine mount through-bolts (large diameter fasteners through mount brackets). Attach engine hoist chains to factory lifting eyes on cylinder heads - use chain leveler to balance engine angle. Note: Exact engine driveplate/coupling-to-torque-tube fastener count for 2009 DB9 with rear-mounted Touchtronic ZF transaxle Note: Exact torque tube flange to engine rear plate fastener count and locations for 2009 DB9 V12
5. 5

   Remove Engine from Vehicle
   Perform final verification that all connections are disconnected: coolant hoses, electrical harnesses, fuel lines, AC lines, transmission, mounts, and exhaust. Apply slight upward tension on hoist. Carefully draw engine forward to separate from the torque tube/driveplate coupling (rear-mounted transaxle via torque tube) while monitoring clearances around firewall, fender wells, and steering components. Tilt engine nose-up approximately 30 degrees as it clears radiator support. Lift slowly and guide engine clear of vehicle. If using engine stand, mount engine to stand using the rear engine plate/adapter bolt pattern before removing hoist.
6. 6

   Remove External Engine Components
   With engine on stand or secure bench, remove remaining accessories: alternator, power steering pump (if not already removed), AC compressor, starter motor, and engine mounts. Remove the valve cover from the cylinder head on the affected bank (approximately 10-12 fasteners per cover, likely Torx or E-Torx). Remove ignition coils and spark plugs from all cylinders on affected bank. Identify and mark the specific cylinder requiring piston replacement.
7. 7

   Remove Timing Chain Covers and Set Engine to TDC
   Remove crankshaft pulley/harmonic balancer using appropriate puller (do not hammer). Remove front timing chain cover (multiple fasteners around perimeter, typically 12-16 fasteners). Photograph timing chain positions and all timing marks on cam sprockets and crank sprocket before disturbing. Rotate crankshaft to TDC on cylinder #1 (or reference cylinder for timing) using the correct socket size on the crank bolt (verify OEM crank bolt size) - align timing marks per OEM procedure. Note cam sprocket positions relative to chain colored links or alignment marks. Note: Rotate crankshaft to TDC on cylinder #1 (or reference cylinder for timing) using the correct socket on the crank bolt (verify crank bolt size against OEM documentation) - align timing marks per OEM procedure.
8. 8

   Remove Cylinder Heads from Affected Bank
   Remove camshaft carrier/cover assemblies if separate from heads. Loosen cylinder head bolts in reverse of tightening sequence (spiral pattern from outside to inside) in multiple passes to prevent warping. Remove cylinder head bolts completely - these are TTY and must be discarded. Carefully lift cylinder heads from block - they are heavy (approximately 40-50 lbs each) and may stick to gasket. Place heads on clean padded surface. Remove and discard old head gaskets. Cover exposed cylinders with clean shop towels to prevent contamination. Note: This procedure assumes left or right bank piston replacement. The single cylinder head on the affected bank (covering all six cylinders of that bank) must be removed to access the piston.
   Torque spec

   Cylinder Head Bolts65 Nm (48 lb-ft)
9. 9

   Inspect Cylinder and Remove Ridge
   Identify the cylinder requiring piston replacement. Rotate crankshaft to bring affected piston to bottom dead center (BDC). Inspect cylinder bore for scoring, glazing, or damage. Measure cylinder bore diameter at top, middle, and bottom in two perpendicular directions using dial bore gauge. Record measurements - maximum taper should not exceed 0.002 inch, maximum out-of-round should not exceed 0.001 inch. Use cylinder ridge reamer to carefully remove ridge at top of cylinder bore where ring travel ends - remove only the ridge, not parent cylinder wall material. Clean cylinder thoroughly with solvent and lint-free cloth.
10. 10

    Remove Connecting Rod and Old Piston
    Rotate crankshaft to bring affected connecting rod to BDC for best access. Mark connecting rod cap orientation to rod body (should already have factory marks, but verify). Remove connecting rod cap bolts - these are TTY and must be discarded. Remove rod cap and lower bearing shell. Push connecting rod and piston assembly upward out of cylinder bore using wooden dowel or plastic handle - never use metal tools against piston crown. Place assembly on clean bench. If reusing connecting rod, secure in soft-jaw vise and remove piston pin circlips with needle-nose pliers. Press or drive piston pin out using appropriate drift. Remove old rings from piston by carefully spreading ring ends and lifting off - note ring orientation and positions.
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
11. 11

    Inspect Crankshaft Journal and Install New Bearings
    Clean connecting rod journal on crankshaft thoroughly with solvent and lint-free cloth. Inspect journal for scoring, discoloration, or out-of-round condition. Measure journal diameter with micrometer - compare to OEM specifications. Verify connecting rod big-end bore is within specification. Install new upper bearing shell into connecting rod (tang engages rod notch - bearing must sit flush without forcing). Install new lower bearing shell into rod cap. Do NOT apply oil yet - use Plastigage to verify bearing clearance: place strip of Plastigage across journal, install cap with NEW connecting rod bolts, torque to specification, remove cap, and measure Plastigage width with gauge card. Bearing clearance should be within the OEM-specified range (verify exact connecting rod bearing clearance specification against OEM documentation). If clearance is acceptable, remove Plastigage completely and lightly oil bearing surfaces with clean engine oil.
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
12. 12

    Prepare and Install New Piston Assembly
    Verify new piston is correct size and grade code matching other pistons in engine (grade codes typically stamped on piston crown). Install piston rings onto new piston in correct order: oil control ring first (expander and rails), then lower compression ring (mark facing down), then top compression ring (mark facing up). Use ring installation tool to prevent ring breakage. Verify ring end gaps by inserting each ring into cylinder bore (squared using piston crown) and measuring gap with feeler gauge - compare against the OEM-specified ring end gap (verify exact specification against OEM documentation). Stagger ring end gaps 120 degrees apart. Install piston pin into piston and connecting rod per OEM method - verify whether the pin is a slip-fit or interference (press) fit requiring rod small-end heating before assembly. Install new piston pin circlips ensuring they fully seat in piston grooves. Coat piston skirt, rings, and cylinder wall liberally with clean engine oil.
13. 13

    Install Piston Assembly into Cylinder
    Orient piston correctly for engine (typically arrow or notch on crown faces timing chain front). Install piston ring compressor around piston ensuring rings are fully compressed and compressor sits flush against piston crown. Guide connecting rod into cylinder bore from top, aligning rod to crankshaft journal. Firmly tap piston crown with wooden or plastic handle to drive piston through ring compressor into cylinder bore - rings should pop into bore smoothly. If excessive resistance is felt, stop and verify ring compressor position and ring gaps. Once piston enters bore, push piston down until rod bearing seats on crankshaft journal. Verify piston moves freely in bore without binding.
14. 14

    Install Connecting Rod Cap and Torque Fasteners
    Ensure bearing shells are clean and lightly oiled. Verify rod cap orientation matches rod body (factory numbers or marks aligned). Install rod cap onto connecting rod. Install NEW connecting rod bolts (TTY - never reuse) and hand-tighten. Torque connecting rod bolts to the OEM-specified initial torque, then perform angle tightening per OEM specification (verify exact initial torque and angle against factory documentation before assembly). Verify final bolt torque angle - bolts should exhibit slight stretch but not yield excessively. After torquing, rotate crankshaft two complete revolutions by hand to verify smooth rotation without binding. Check connecting rod side clearance with feeler gauge (typical specification 0.006-0.012 inch). Note: Torque connecting rod bolts to the OEM-specified initial torque, then perform angle tightening per OEM specification (verify exact initial torque and angle values against OEM documentation before proceeding).
    Torque spec

    Connecting Rod Bolts45 Nm (33 lb-ft)
15. 15

    Install Cylinder Heads with New Gaskets
    Thoroughly clean cylinder head mating surfaces and engine block deck surfaces using plastic scraper - remove all old gasket material without scratching surfaces. Verify deck surface flatness if possible (should be within 0.002 inch over full length). Install new head gaskets onto block aligning all coolant and oil passages - gaskets are sided and directional (verify 'TOP' and 'FRONT' markings). Carefully lower cylinder heads onto block - align dowel pins and ensure gaskets remain positioned. Install NEW cylinder head bolts (TTY - never reuse old bolts) finger-tight. Torque head bolts in the OEM-specified sequence and staged torque/angle values (verify exact torque sequence, initial torque, and angle specifications against factory documentation before assembly). Note: Torque head bolts in the OEM-specified sequence in the OEM-specified stages and angles (verify exact torque values, sequence, and angle specifications against OEM documentation before proceeding).
    Torque spec

    Cylinder Head Bolts65 Nm (48 lb-ft)
16. 16

    Reinstall Timing Chain and Front Cover
    Rotate crankshaft to TDC position matching timing marks photographed during disassembly. Verify all cam sprocket positions and colored chain links align with marks. Double-check timing alignment before proceeding - this is critical for engine survival. Install new front cover gasket and crankshaft front seal. Install timing chain cover with fasteners torqued to specification (typically 10-12 Nm). Install crankshaft pulley/harmonic balancer ensuring keyway is aligned - torque center bolt to OEM specification (verify exact torque and whether torque-plus-angle procedure and new bolt are required). Rotate crankshaft two full revolutions and recheck timing mark alignment. Note: Install crankshaft pulley/harmonic balancer ensuring keyway is aligned - torque center bolt to the OEM-specified value (verify exact torque and any angle/TTY requirement against OEM documentation).
17. 17

    Reinstall External Engine Components and Valve Covers
    Install all spark plugs torqued to the OEM-specified value (verify exact spark plug torque against OEM documentation — typically lower for aluminum heads). Install ignition coils with electrical connectors. Install new valve cover gaskets and reinstall valve covers with fasteners torqued in sequence from center outward to specification (typically 8-10 Nm). Reinstall engine accessories: starter, alternator, power steering pump, AC compressor, and engine mounts. Verify all fasteners are torqued properly.
18. 18

    Install Engine into Vehicle
    Reverse removal procedure to install engine. Attach hoist to lifting eyes and carefully guide engine into engine bay at appropriate angle (nose-up initially). Align engine to torque tube coupling and dowels. Push engine rearward until fully seated against the torque tube flange. Install torque tube coupling fasteners hand-tight. Install engine mount through-bolts and torque to specification. Remove hoist and torque all torque tube coupling fasteners. Reinstall driveplate/coupling bolts with alignment marks matched - torque per OEM sequence.
19. 19

    Reconnect All Engine Systems
    Reconnect exhaust downpipes to manifolds. Install intake manifold with new gaskets torqued in proper sequence. Reconnect all fuel lines, vacuum lines, PCV hoses, and evaporative emissions lines. Reconnect all electrical connectors: main engine harness, alternator, starter, sensors, ignition coils, throttle bodies. Reconnect coolant hoses, heater hoses, oil cooler lines, and transmission cooler lines. Install radiator/condenser assembly and cooling fans. Install accessory drive belts. Reconnect AC lines - do NOT charge system yet.
20. 20

    Install Front End Components and Fill Fluids
    Install radiator support and hood latch assembly. Install front bumper cover and undertray. Install new oil filter. Install oil drain plug with NEW crush washer torqued to OEM specification (verify exact drain plug torque — typically 25-30 Nm for aluminum oil pans). Fill engine with the OEM-specified quantity of synthetic engine oil (verify exact capacity per OEM specification; approximately 10.5–12 quarts including filter). Fill cooling system with the OEM-specified quantity of OAT 50/50 coolant (verify exact capacity per OEM specification) - bleed air from system using bleeder screws on coolant pipes. Reconnect battery positive then negative terminals. Note: Fill engine with the OEM-specified quantity and grade of synthetic engine oil (verify exact capacity and oil grade against OEM documentation). Note: Install oil drain plug with NEW crush washer torqued to the OEM-specified value (verify exact drain plug torque against OEM documentation). Note: Fill cooling system with the OEM-specified quantity of approved OAT 50/50 coolant - bleed air from system using bleeder screws on coolant pipes (verify exact coolant capacity against OEM documentation).
    Torque spec

    Oil Drain Plug35 Nm (26 lb-ft)
21. 21

    Initial Start and Break-In
    Perform pre-start checks: verify oil level on dipstick, verify coolant level, inspect for leaks, verify all connectors seated. Turn ignition to ON position without starting - listen for fuel pump priming (approximately 5 seconds). Check for fuel leaks at rail connections. Crank engine for 5-10 seconds without starting to build oil pressure. Start engine and immediately verify oil pressure indication on dashboard. Allow engine to idle and monitor for unusual noises, vibrations, or leaks. Engine may run rough initially until fuel trims adapt. Monitor coolant temperature and verify cooling fans cycle properly. After engine reaches operating temperature, shut down and recheck all fluid levels. Inspect for any coolant, oil, or fuel leaks.
22. 22

    AC Recharge and Final Systems Check
    Evacuate AC system using vacuum pump for minimum 30 minutes to remove air and moisture. Recharge AC system with R-134a refrigerant to proper specification using AC machine. Verify AC compressor operation and cooling performance. Test drive vehicle for minimum 30 minutes at varying speeds and loads. Avoid sustained high RPM or full throttle for first 500 miles of break-in. Monitor engine temperature, oil pressure, and all gauges during test drive. After test drive, recheck all fluid levels and inspect for leaks. Verify no diagnostic trouble codes stored in engine control module.

Reassembly

1. Reassembly is performed in reverse order of disassembly with critical attention to timing chain alignment, torque-to-yield fastener replacement, and proper torque sequences.
2. All torque-to-yield fasteners (cylinder head bolts, connecting rod bolts) must be replaced with new parts - never reuse TTY fasteners.
3. Timing chain alignment is critical - verify all timing marks align at TDC before installing front cover and before first start attempt.
4. Use new gaskets for all major components: cylinder heads, intake manifold, exhaust manifolds, valve covers, timing cover, and oil pan if disturbed.
5. Follow proper break-in procedure: avoid sustained high RPM or full load for first 500 miles to allow rings to properly seat.

Verification

• Rotate crankshaft two complete revolutions by hand before initial start - verify smooth rotation without binding or unusual resistance.
• Verify timing chain alignment marks at TDC after installation and after two-revolution rotation check.
• Check engine oil pressure immediately upon first start - should read minimum 20 PSI at idle when warm.
• Monitor coolant temperature gauge during warm-up cycle - should reach and maintain normal operating temperature (typically 180-200°F) without overheating.
• Inspect for any oil, coolant, or fuel leaks after first start and after test drive - pay particular attention to head gasket, valve covers, and timing cover areas.
• Verify no unusual noises from bottom end during idle and light throttle - connecting rod bearing noise presents as metallic knocking that increases with RPM.
• Check for diagnostic trouble codes after test drive - should show no stored codes related to mechanical or timing issues.
• Verify smooth idle and proper throttle response - V12 should idle smoothly without misfires or excessive vibration.
• Recheck all fluid levels after test drive when engine is fully warmed up and then cooled - top off as necessary.
• Perform cylinder compression test and leak-down test if any concerns about ring seal or valve sealing exist.

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