Coolant Flush

Drain, flush, and refill the cooling system on a 2009 Aston Martin DB9 6.0L V12, replacing coolant with fresh OAT 50/50 mixture to maintain optimal engine temperature regulation.

Warnings

Tools required

Parts

• Radiator drain plug washer or O-ring × 1 — Use OEM specification

Fluids

• OAT 50/50 coolant — 10.5 qt

Preparation

1. Park vehicle on level surface and apply parking brake. Place wheel chocks behind rear wheels.
2. Ensure engine is completely cold. Remove engine cover by releasing retaining clips.
3. Raise front of vehicle with floor jack and support securely on jack stands at manufacturer-designated lift points.
4. Remove front undertray panels to access radiator drain plug and lower coolant hoses. Panels are typically secured with Torx fasteners.
5. Place drain pan beneath radiator drain point.

Procedure

1. 1

   Relieve cooling system pressure
   Slowly turn the pressurized expansion tank (header tank) cap counterclockwise to release any residual pressure. Wait for any hissing to stop, then remove the cap completely. Set aside in a clean location.
2. 2

   Drain coolant from radiator
   Locate the radiator drain point at the bottom of the radiator. The DB9 radiator does not use a conventional threaded drain plug; draining is performed by disconnecting the lower radiator hose. Position drain pan directly beneath, then release the hose clamp and carefully disconnect the lower radiator hose to allow coolant to drain completely. Inspect the hose and clamp for damage and replace if deteriorated. Verify the drain method against Aston Martin service documentation before proceeding. or O-ring for damage and replace if compressed or cracked. Note: Locate the radiator drain point at the bottom of the radiator. Note: if no drain plug is fitted, the system must be drained by disconnecting the lower radiator hose. Verify location against Aston Martin service documentation. Note: Locate the radiator drain point at the bottom of the radiator (verify location and whether a drain plug or lower hose removal is required per the factory manual).
3. 3

   Drain coolant from engine block
   If equipped, locate the engine block drain plug(s) on the lower section of the engine block. Verify their presence and location against Aston Martin service documentation, as block drains may not be fitted. Remove the drain plug using the appropriate socket and allow additional coolant to drain. Inspect block drain plug washer and replace with new copper washer if equipped. Note: Check factory documentation to confirm whether the 6.0L V12 is equipped with engine block drain plugs and their location. If equipped, remove the drain plug(s) using the appropriate socket and allow additional coolant to drain. Inspect any drain plug sealing washer and replace with the correct OEM-specified washer if equipped. Note: If equipped, locate the engine block drain plug(s) on the lower section of the engine block per the factory workshop manual; note that some V12 applications are drained via the lower radiator hose rather than dedicated block drains.
   Torque spec

   Block Drain Plug25 Nm (18 lb-ft)
4. 4

   Inspect lower coolant hoses
   With coolant drained, inspect all accessible lower coolant hoses for cracks, softness, or deterioration. Check hose clamps for corrosion. If any hoses show signs of failure, this is the optimal time to replace them.
5. 5

   Reinstall drain plugs
   Install new washer on block drain plug if equipped. Thread block drain plug in by hand to ensure proper thread engagement, then torque to specification. Reconnect the lower radiator hose and secure the hose clamp to specification (replace clamp if corroded).
   Torque spec

   Block Drain Plug25 Nm (18 lb-ft)
6. 6

   Flush cooling system (optional but recommended)
   If performing a full flush, use distilled water (not tap water) through the system until it runs clear from the drain point, then drain fully. Avoid tap water to prevent mineral deposits in the aluminum cooling system. Reconnect the lower radiator hose and secure the clamp when complete.
   Torque spec

   Block Drain Plug25 Nm (18 lb-ft)
7. 7

   Locate and open bleed screw
   Locate the coolant bleed/vent screw(s) for the DB9 V12 cooling system per factory documentation, as the V12 may have multiple bleed points. Confirm location before opening. Open the bleed screw 2-3 turns to allow air to escape during filling. Leave open until solid coolant flows from the bleed point.
   Torque spec

   Bleed Screw8 Nm (6 lb-ft)
8. 8

   Begin coolant fill
   Using a funnel with spout inserted into the coolant expansion (header) tank, slowly pour the Aston Martin-specified OEM coolant (50/50 pre-mixed; verify chemistry and spec against factory documentation) into the system. Fill slowly to allow air to escape through the open bleed screw. The V12 configuration has multiple air pockets that must be purged.in OEM-specified 50/50 pre-mixed coolant into the system. Note: slowly pour the Aston Martin-specified coolant (verify chemistry and spec in the factory manual), pre-mixed 50/50, into the system
9. 9

   Close bleed screw and complete fill
   When solid coolant (no air bubbles) flows from the bleed screw, close and torque the bleed screw to specification. Continue filling the reservoir to the MAX or FULL COLD mark. Total system capacity should be confirmed against Aston Martin service documentation for the 2009 DB9 6.0L V12 before filling.ainst the factory workshop manual for the 2009 DB9 6.0L V12 before filling.
   Torque spec

   Bleed Screw8 Nm (6 lb-ft)
10. 10

    Run engine to purge air
    Install coolant reservoir cap securely. Start engine and allow it to idle with heater set to maximum temperature. Monitor coolant level in reservoir and add coolant as level drops during air purge. Run until cooling fans cycle on and off at least once, indicating thermostat has opened and coolant is circulating fully.
    ⚠Monitor engine temperature gauge closely. If temperature rises above normal operating range, shut off engine immediately and allow to cool before continuing.
11. 11

    Check for leaks and verify level
    With engine at operating temperature, inspect all drain plugs, hose connections, and radiator seams for coolant leaks. Shut off engine and allow to cool for 15 minutes. Recheck coolant level in reservoir and top off to MAX mark if necessary. Reinstall coolant reservoir cap.
12. 12

    Reinstall undertray and lower vehicle
    Reinstall front undertray panels and secure with Torx fasteners. Ensure all panels are properly aligned and seated. Lower vehicle from jack stands and remove stands. Install engine cover.

Reassembly

1. Ensure all drain plugs are torqued to specification with new washers installed where applicable.
2. Verify coolant reservoir cap is installed securely to maintain system pressure.
3. All undertray panels must be properly secured to prevent aerodynamic disruption and component damage.
4. Double-check that no tools or rags were left in the engine bay before closing hood.

Verification

• Start engine and verify no coolant leaks from drain plugs, hoses, or connections.
• Confirm engine reaches normal operating temperature and cooling fans cycle properly.
• Check coolant level after 24-48 hours of driving and top off if necessary as remaining air purges from system.
• Verify heater produces hot air at idle, confirming proper coolant circulation through heater core.
• Use coolant hydrometer or refractometer to verify proper 50/50 mixture concentration for adequate freeze and boil-over protection.

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