Front Main Seal

Remove and replace the front crankshaft main seal on a 2009 Aston Martin DB9 6.0L V12, requiring removal of the front subframe, engine accessories, timing cover, and timing chains to access the seal behind the crankshaft sprocket.

Warnings

Tools required

Parts

• Front crankshaft main seal × 1 — Use OEM specification
• Timing cover gasket set × 1 — Use OEM specification
• Oil pan gasket (front section) × 1 — Use OEM specification
• Crankshaft pulley/harmonic balancer bolt × 1 — TTY - use OEM specification
• Engine oil and filter × 1 — Use OEM specification
• Engine coolant 50/50 pre-mix × 1 — OAT compatible
• RTV silicone sealant (OEM approved) × 1 — Use OEM specification
• Oil drain plug crush washer × 1 — Use OEM specification
• Timing chain tensioner seals (if disturbed) × 2 — Use OEM specification

Fluids

• 5W-30 engine oil — 10.5 qt
• OAT 50/50 coolant — 10.5 qt

Preparation

1. Ensure engine is completely cool to the touch (allow minimum 3 hours after last operation).
2. Disconnect negative battery terminal and isolate cable end away from battery post.
3. Remove engine cover panels and undertray to access engine bay and underside components.
4. Place vehicle on level ground with wheels chocked, then raise and support on jack stands at all four corners at manufacturer-specified lift points.
5. Position coolant and oil drain pans under vehicle.
6. Drain engine coolant completely by opening radiator petcock and removing coolant reservoir cap.
7. Drain engine oil completely and remove oil filter.
8. Relieve fuel system pressure by removing fuel pump fuse and cranking engine briefly (with battery reconnected temporarily, then disconnect again).
9. Remove front wheels to access front suspension and subframe mounting points.
10. Remove front bumper cover to access radiator and cooling system components.
11. Take detailed photographs of all belt routing, hose connections, and harness routing for reference during reassembly.

Procedure

1. 1

   Remove Front Cooling System Components
   Disconnect upper and lower radiator hoses from radiator. If the vehicle routes transmission cooler lines through the front radiator, disconnect them; note that the DB9 uses a rear-mounted transaxle, so verify cooler location and routing before disconnecting. Remove radiator mounting brackets and lift radiator assembly out of vehicle. Disconnect electrical connectors from cooling fans. Remove cooling fan assembly as a unit. Disconnect heater hoses that may interfere with subframe removal. Disconnect heater hoses that may interfere with subframe removal. Note: If equipped with an automatic transaxle, disconnect any transmission cooler lines in the area; verify cooler location and routing against the Aston Martin workshop manual (the Touchtronic transaxle is rear-mounted). Note: Remove any air intake ducting or shrouds at the front of the engine if they obstruct access.
2. 2

   Remove Accessory Drive Components
   Photograph serpentine belt routing for reference. Using the correct tensioner tool, release tension on each accessory drive belt and remove the belt(s). Note that this V12 may use more than one accessory drive belt; verify belt configuration and routing against the Aston Martin workshop manual. Remove power steering pump mounting bolts and secure pump aside with hoses still attached (do not allow pump to hang by hoses). Remove air conditioning compressor mounting bolts and secure compressor aside without disconnecting refrigerant lines. Remove alternator mounting bolts and disconnect electrical connections, then remove alternator from vehicle.
3. 3

   Remove Crankshaft Pulley
   Install crankshaft holding tool to prevent crankshaft rotation. Using a breaker bar or impact wrench, remove the crankshaft pulley center bolt (turning counter-clockwise). This bolt is a high-torque TTY fastener and may require significant force; verify exact torque and angle specification against Aston Martin service data before removal. Once bolt is removed, install a harmonic balancer puller onto the crankshaft pulley and evenly tighten the puller to draw the pulley off the crankshaft snout. Remove pulley and set aside. Inspect crankshaft snout for any damage or scoring. Note: This bolt is torque-to-yield and torqued to the manufacturer-specified value plus an angle stage; verify the exact specification from Aston Martin service data before removal and reuse. Note: This bolt is a high-torque TTY fastener that may require significant force to remove; verify exact torque and any torque-angle specification against the Aston Martin workshop manual before reassembly.
   Torque spec

   Crankshaft Pulley Bolt180 Nm (133 lb-ft)
4. 4

   Support Engine and Remove Front Subframe
   Install an engine support fixture across the engine bay or attach overhead hoist chains to engine lifting eyes. Ensure engine is securely supported with minimal slack in support system. Position transmission jack or support stands under front subframe. Remove the front subframe mounting bolts connecting subframe to chassis; verify the exact bolt count and locations from Aston Martin service data. Carefully lower subframe approximately 6-8 inches to create clearance for timing cover removal. Ensure all electrical connectors, brake lines, and steering components have sufficient slack or have been disconnected. Do not fully remove subframe unless absolutely necessary for clearance. Note: Remove the front subframe mounting bolts, noting their exact count and locations; verify the number and torque specification against the Aston Martin workshop manual before removal.
5. 5

   Disconnect Timing-Related Sensors and Components
   Disconnect crankshaft position sensor electrical connector and remove sensor from timing cover (typically 1 bolt). Disconnect camshaft position sensor connectors (one per bank). Remove any brackets, harness clips, or accessory components still attached to timing cover that would prevent its removal. Verify all electrical connections to timing cover area are disconnected.
6. 6

   Remove Timing Cover Fasteners
   Remove all timing cover bolts, noting their locations as there are multiple lengths and sizes. Remove all timing cover bolts, noting locations and lengths. Verify the exact bolt count, head sizes, and removal sequence from Aston Martin service data before proceeding. Verify all fasteners are removed before attempting to separate cover. If front oil pan section bolts into timing cover, remove those fasteners as well. Note: Timing Cover Bolts - smaller size (verify head type/size against Aston Martin service data) Note: Timing Cover Bolts - larger size (verify head type/size against Aston Martin service data)
   Torque spec

   Timing Cover Bolts - 10mm45 Nm (33 lb-ft)

   Timing Cover Bolts - 8mm25 Nm (18 lb-ft)
7. 7

   Remove Timing Cover
   Carefully work timing cover away from engine block. The cover may be sealed with RTV in addition to a gasket. Use a non-marring pry tool in designated pry points if necessary, working around the perimeter to break the seal. Once cover is loose, carefully pull it straight out to clear the crankshaft snout. Be extremely careful not to damage the sealing surfaces on the block or cover. Remove and discard old gasket material and clean all RTV residue from both mating surfaces using appropriate solvent.
8. 8

   Lock Timing Chain System
   Verify engine is at TDC for cylinder #1 by checking timing marks on crankshaft and camshaft sprockets align with reference marks on engine block and heads. Install camshaft timing tools into both camshaft banks to lock camshafts in position. Install timing chain tensioner retaining pins or clips on both primary timing chain tensioners to lock tensioners in retracted position. This prevents chain tension loss and maintains timing while working. Document or photograph timing mark alignment for reassembly reference.
9. 9

   Remove Crankshaft Timing Gear
   With timing locked and crankshaft holding tool installed, remove the crankshaft timing gear retaining bolt (if separate from main pulley bolt already removed). Carefully slide the crankshaft timing sprocket(s) forward off the crankshaft. The DB9 may have a single sprocket driving dual chains or separate sprockets - remove as an assembly maintaining chain engagement if possible. Note the orientation and any alignment marks on the sprocket. Set timing components aside in clean area.
10. 10

    Remove Front Main Seal
    With timing sprocket removed, the front main seal is now accessible in the timing cover bore (or front engine block bore depending on design). Using a front seal removal tool or seal puller, carefully extract the old seal from its bore. Work around the perimeter evenly to avoid cocking the seal in the bore. Alternatively, carefully drill a small hole in the seal face and use a slide hammer with self-tapping tip. Take extreme care not to damage the seal bore in the timing cover or the crankshaft sealing surface. Inspect crankshaft seal surface for any grooves, scoring, or damage that could cause the new seal to leak.
11. 11

    Install New Front Main Seal
    Thoroughly clean the seal bore and crankshaft seal surface with lint-free cloth and solvent. Ensure no debris, oil, or old gasket material remains. Lightly lubricate the new seal outer diameter and seal lip with clean engine oil. Verify seal orientation (spring side typically faces inward toward engine). Using appropriate diameter seal installation driver, carefully drive new seal into bore, keeping seal square to bore throughout installation. Drive seal until flush with outer surface or to specified depth. Verify seal is seated evenly around entire circumference. Apply a thin coat of clean engine oil to seal lip where it will contact crankshaft.
12. 12

    Reinstall Crankshaft Timing Gear
    Ensure crankshaft snout and timing gear bore are clean and dry. Carefully slide crankshaft timing sprocket(s) back onto crankshaft, aligning any keyways and ensuring timing marks are properly positioned to match previous documentation. Install crankshaft sprocket retaining bolt (if applicable) and torque to specification. Verify timing chain engagement is correct and timing marks still align with camshaft timing tools installed.
13. 13

    Prepare and Install Timing Cover
    Thoroughly clean all RTV and gasket residue from timing cover mating surface and engine block mating surface using gasket scraper and solvent. Surface must be completely clean and dry. Install new timing cover gasket per manufacturer instructions. Apply thin bead of OEM-approved RTV silicone to areas specified in service manual (typically around coolant passages and oil pan junction). Carefully position timing cover over crankshaft snout, aligning dowel pins with cover. Press cover fully against engine block, ensuring gasket remains properly positioned.
14. 14

    Install Timing Cover Fasteners
    Install all timing cover bolts in their correct locations, starting with 10mm head bolts. Thread all bolts finger-tight before torquing any fasteners. Torque timing cover bolts in the manufacturer-specified cross-pattern sequence to the values given in Aston Martin service data; verify each fastener's torque spec and tightening order before proceeding. If the front oil pan section was removed, torque those fasteners to the AML-specified value. Verify no bolts were missed. Note: Torque the larger timing cover bolts and the smaller timing cover bolts to the Aston Martin specified values in a cross-pattern sequence working from center outward. If front oil pan section was removed, torque those fasteners to the specified oil pan bolt torque. Verify all torque values against factory service data before assembly. Note: Torque the larger timing cover bolts and the smaller bolts to the manufacturer-specified values in a cross-pattern sequence working from center outward. If the front oil pan section was removed, torque those fasteners to specification. Verify all timing cover and oil pan torque values against the Aston Martin workshop manual.
    Torque spec

    Timing Cover Bolts - 10mm45 Nm (33 lb-ft)

    Timing Cover Bolts - 8mm25 Nm (18 lb-ft)

    Oil Pan Bolt12 Nm (9 lb-ft)
15. 15

    Remove Timing Locks and Reinstall Sensors
    Carefully remove camshaft timing tools from both cylinder banks. Remove timing chain tensioner retaining pins/clips to allow tensioners to apply proper chain tension. Manually rotate crankshaft two complete revolutions clockwise (using crankshaft holding tool location) and verify timing marks return to TDC alignment position. This confirms timing is correct. Reinstall crankshaft position sensor with new O-ring if equipped, torque to specification. Reconnect camshaft position sensor connectors.
16. 16

    Reinstall Crankshaft Pulley
    Ensure crankshaft snout is clean and free of oil (use brake cleaner if necessary for proper pulley fit). Slide crankshaft pulley/harmonic balancer onto crankshaft snout, aligning keyway. Verify against Aston Martin service data whether the pulley is a slide-on or press/interference fit; if it is an interference fit it must be drawn on using the appropriate installation tool or the main bolt, not forced by hand. Install new crankshaft pulley bolt (these are TTY and must not be reused). Using crankshaft holding tool to prevent rotation, torque bolt to the Aston Martin specified base torque followed by the specified angle (torque-plus-angle); verify exact values against factory service data before assembly. Remove crankshaft holding tool. Note: Install new crankshaft pulley bolt (these are TTY and must not be reused). Using crankshaft holding tool to prevent rotation, torque bolt to the manufacturer-specified initial value, then apply the specified torque angle using an angle gauge per Aston Martin service data. Note: Install new crankshaft pulley bolt (these are TTY and must not be reused). Using crankshaft holding tool to prevent rotation, torque the bolt to the manufacturer-specified initial torque followed by the specified torque angle using an angle gauge. Verify exact torque and angle values against the Aston Martin workshop manual before tightening.
    Torque spec

    Crankshaft Pulley Bolt180 Nm (133 lb-ft)
17. 17

    Raise Subframe and Reinstall Front Accessories
    Using transmission jack or support stands, carefully raise front subframe back into position, aligning mounting holes with chassis. Install subframe mounting bolts and torque to specification. Remove engine support fixture. Reinstall alternator with mounting bolts and reconnect electrical connections. Reinstall air conditioning compressor with mounting bolts. Reinstall power steering pump with mounting bolts. Install serpentine belt following routing diagram documented during removal, using tensioner tool to load tensioner.
18. 18

    Reinstall Cooling System Components
    Reinstall cooling fan assembly and connect electrical connectors. Position radiator into mounting brackets and secure with mounting hardware. Connect upper and lower radiator hoses with new clamps if originals are worn. Reconnect transmission cooler lines if they were disconnected at the radiator. Reconnect heater hoses. Note: Reinstall any air intake ducting or ancillary components if removed.
19. 19

    Refill Fluids and Final Assembly
    Install new oil filter and install oil drain plug with new crush washer, torquing to the Aston Martin specified drain plug torque (verify value before tightening to avoid stripping the pan threads). Fill engine with the Aston Martin specified quantity and grade of engine oil per factory specification (verify capacity and viscosity before filling). Close coolant drain and refill the cooling system with the Aston Martin-specified coolant type and 50/50 mixture to the manufacturer-specified capacity (verify total cooling system capacity against factory data before filling), then bleed air per procedure. Reinstall front bumper cover. Reinstall front wheels and torque lug nuts to specification. Reinstall undertray and engine covers. Reconnect negative battery terminal. Note: Close coolant drain and refill cooling system with the Aston Martin specified quantity of the correct specification 50/50 coolant mixture (verify capacity and coolant type before filling), then bleed the system per factory procedure. Note: Fill engine with the Aston Martin-approved grade and quantity of engine oil per specification, then verify level on the dipstick. Note: Install new oil filter and install oil drain plug with new crush washer, torquing to the Aston Martin-specified value. Note: Fill engine with the manufacturer-specified quantity and grade of engine oil, verified against the Aston Martin workshop manual. Note: Install new oil filter and install oil drain plug with new crush washer, torquing to the manufacturer-specified value. Verify drain plug torque against the Aston Martin workshop manual. Note: Close coolant drain and refill the cooling system with the manufacturer-specified quantity and type of coolant (50/50 pre-mix), verified against the Aston Martin workshop manual.
    Torque spec

    Oil Drain Plug25 Nm (18 lb-ft)

Reassembly

1. All fasteners must be torqued to specification in the correct sequence to ensure proper sealing and prevent component failure.
2. Timing alignment is critical - always verify timing marks align after reassembly and after rotating engine two full revolutions.
3. New gaskets and seals must be used; never reuse timing cover gaskets or front main seal.
4. The crankshaft pulley bolt is typically torque-to-yield and must be replaced with new hardware.
5. Ensure all electrical connectors are fully seated and locked before operation.
6. RTV sealant requires cure time - consult product specifications before filling fluids or starting engine.

Verification

• With engine at operating temperature, inspect front main seal area for any oil leakage using clean paper towel or white cloth.
• Verify no coolant leaks from timing cover or hose connections.
• Check engine oil level on dipstick and verify it is at proper full mark.
• Check coolant level in reservoir after engine reaches operating temperature and cooling fans cycle.
• Listen for any abnormal timing chain noise - properly tensioned chains should be quiet during operation.
• Scan for diagnostic trouble codes related to crankshaft or camshaft position sensors.
• Road test vehicle to verify normal operation under load and at various RPM ranges.
• Re-inspect seal area after 100 miles of operation for any evidence of oil seepage.
• If available, use UV dye added to oil and UV light inspection to verify seal integrity.

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