Radiator Hoses - Both

Replace both upper and lower radiator hoses on the 2009 Aston Martin DB9 6.0L V12, requiring partial coolant drain, hose clamp removal, and system refill with bleeding.

Warnings

Tools required

Parts

• Upper radiator hose × 1 — Use OEM specification
• Lower radiator hose × 1 — Use OEM specification
• Hose clamps (if reusing originals show wear) × 4 — OEM constant-tension clamps recommended

Fluids

• OAT 50/50 coolant — 10.5 qt

Preparation

1. Ensure engine is completely cold to the touch (minimum 2 hours after last operation).
2. Park vehicle on level surface and engage parking brake.
3. Raise vehicle on lift or securely support on jack stands rated for vehicle weight.
4. Place coolant drain pan beneath engine with minimum 12 quart capacity.
5. Remove engine cover by releasing quick-release fasteners (typically hand-turn quarter-turn fasteners).
6. Photograph hose routing and clamp positions before disassembly for reference during installation.

Procedure

1. 1

   Drain cooling system
   Locate the coolant drain point (radiator petcock, lower hose, or block drain as applicable) per factory documentation, accessed from underneath the vehicle. Slowly loosen the drain plug using appropriate tool, allowing coolant to drain into collection pan. Once flow reduces to drips, remove drain plug completely and allow system to drain fully. The amount drained will depend on the drain point used; drain as fully as possible to minimize coolant loss during hose replacement.
   Torque spec

   Coolant Drain Plug15 Nm (11 lb-ft)
2. 2

   Access upper radiator hose connections
   From the engine bay, locate the upper radiator hose connecting the top of the radiator to the engine coolant outlet/thermostat housing. Verify the exact routing and thermostat housing location against factory service documentation for this V12 before proceeding. Clear any wiring harnesses or vacuum lines that may obstruct access to hose clamps, taking care not to disconnect them. Note: From the engine bay, locate the upper radiator hose connecting the top of the radiator to the coolant outlet/thermostat housing on the engine. Verify the exact connection point against the original routing, as the DB9 V12 coolant outlet location should be confirmed before removal. Note: From the engine bay, locate the upper radiator hose connecting the top of the radiator to the coolant outlet/thermostat housing on the engine. Verify the exact connection point and housing location against OEM documentation before proceeding, as V12 engine-side routing varies.
3. 3

   Remove upper radiator hose
   Using hose clamp pliers or flat-blade screwdriver, loosen the hose clamp at the radiator end of the upper hose. Slide clamp away from connection point along the hose. Repeat for the clamp at the thermostat housing end. Twist the hose gently to break the seal, then pull firmly to remove from both connections. Residual coolant will drain from hose; have shop towels ready. Inspect both connection points for corrosion or damage.
4. 4

   Access lower radiator hose connections
   From underneath the vehicle, locate the lower radiator hose connecting the bottom of the radiator to the water pump inlet or engine block. Confirm the lower hose routing against the original configuration, as its path along the engine should be verified on the specific vehicle before removal. Verify access to both clamps at radiator outlet and engine inlet. Additional coolant may drain when hose is disturbed. Note: Verify the lower hose routing against factory service documentation and the photographs taken during preparation before proceeding. Note: Verify the lower hose routing against the original path photographed during preparation, as routing side may vary on the DB9 V12.
5. 5

   Remove lower radiator hose
   Loosen the hose clamp at the radiator outlet end using hose clamp pliers or screwdriver. Slide clamp away from connection. Loosen the clamp at the engine inlet end, confirming the exact connection point (water pump inlet) on the specific vehicle, and slide away. Twist hose gently to break seal at both ends, then remove hose completely. Allow any remaining coolant to drain into collection pan. Inspect connection surfaces for corrosion, scale buildup, or damage that could cause leaks.
6. 6

   Prepare new hoses and connections
   Clean both radiator connection points and engine-side connection points using a clean rag. Remove any old coolant residue, corrosion, or rubber deposits from connection surfaces. Verify new hoses match original routing and length. If reusing original clamps, inspect for distortion, corrosion, or weakened spring tension; replace if questionable. Position new clamps on hoses before installation, with screw mechanisms positioned for easy access after hose is in place.
7. 7

   Install new lower radiator hose
   Route the new lower radiator hose into position following the original path. Firmly press the hose onto the radiator outlet connection until it seats completely against the stop bead. Press the engine-side connection onto the water pump or block inlet until fully seated. Position hose clamps over the connection points, approximately 10-15mm from the hose ends. If using worm-gear clamps, tighten snugly until the hose is secured without cutting into the rubber; constant-tension spring clamps simply clip into place and are not torqued. Note: If using worm-drive clamps, tighten snugly until the hose is secured without cutting into the rubber; if using OEM constant-tension spring clamps, simply position and release them to self-tension (no torque spec applies).
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
8. 8

   Install new upper radiator hose
   From the engine bay, route the new upper radiator hose into position. The hose may have a specific orientation; match any molded bends or curves to the original routing photographed during removal. Press hose firmly onto the radiator inlet connection until fully seated against stop bead. Press the thermostat housing end onto its connection until fully seated. Position hose clamps over both connections, approximately 10-15mm from hose ends. If using worm-drive clamps, tighten snugly to secure the hose without cutting the rubber; OEM constant-tension clamps self-tension and require no torque spec.
   Torque spec

   Hose Clamps3 Nm (2 lb-ft)
9. 9

   Reinstall drain plug and prepare for refill
   Clean the coolant drain plug and its sealing surface. Install the drain plug/petcock and tighten to the manufacturer-specified value (verify spec; most radiator drain petcocks are hand-snug only). Ensure any displaced wiring harnesses or vacuum lines are returned to their original positions and secured with clips. Lower vehicle if raised, or ensure safe access to coolant expansion tank/radiator cap for refilling. Note: Install drain plug and tighten per OEM specification; note that plastic radiator petcock-style plugs are typically hand-tightened only and should not be over-torqued.
   Torque spec

   Coolant Drain Plug15 Nm (11 lb-ft)
10. 10

    Refill cooling system
    Locate the coolant expansion tank (typically on driver side of engine bay). Remove expansion tank cap. Using a funnel, slowly pour the Aston Martin-approved OAT 50/50 coolant mixture into the expansion tank per factory specification. Fill until coolant level reaches the MAX or COLD FILL line. Verify the total system capacity against factory specification before refilling; the amount needed to restore level after a partial drain will depend on how much was drained, so add coolant incrementally and confirm actual system capacity against OEM documentation. Allow coolant to settle and top off as needed. Note: Using a funnel, slowly pour the manufacturer-specified OAT-type coolant (verify Aston Martin specification) in a 50/50 mixture into the expansion tank. Note: Confirm the total cooling system capacity against factory specifications; approximately 60-70% of system capacity will be needed to restore level after this partial drain. Note: Confirm the total system capacity against OEM documentation before refilling; the amount needed to restore level after a partial drain will vary; add coolant incrementally and verify the actual total system capacity against OEM documentation.
11. 11

    Bleed cooling system
    With expansion tank cap still removed, start engine and allow to idle. Turn heater controls to maximum temperature and maximum fan speed to open heater core circuit. Monitor coolant level in expansion tank as engine warms; air bubbles will be purged and level will drop. Add coolant as needed to maintain proper level. Continue running engine until cooling fans cycle on (indicating thermostat has opened and system is at operating temperature). Rev engine gently to 2000-2500 RPM several times to help purge trapped air. After fans cycle and no additional air bubbles emerge, shut off engine and allow to cool for 15-20 minutes.
    ⚠Monitor engine temperature gauge during bleeding process. If temperature rises above normal range before fans cycle, shut off engine immediately and investigate for blockages or additional leaks.
12. 12

    Final coolant level adjustment
    After engine has cooled (expansion tank no longer under pressure), check coolant level with engine cold. Level should be at MAX or COLD FILL line on expansion tank. Add coolant if needed to reach proper level. Securely reinstall expansion tank cap. Reinstall engine cover by engaging quick-release fasteners.

Reassembly

1. Ensure all hose clamps are tightened to specified torque and positioned correctly over connection points.
2. Verify all wiring harnesses and vacuum lines are secured in original positions and not contacting hot engine components.
3. Confirm coolant expansion tank cap is securely installed to maintain system pressure.
4. Engine cover must be properly seated with all quick-release fasteners engaged.

Verification

• With engine cold, visually inspect all four hose connections (upper radiator-side, upper engine-side, lower radiator-side, lower engine-side) for signs of coolant seepage or wetness.
• Start engine and bring to full operating temperature while monitoring for leaks at all hose connections. Use a work light and mirror if needed to inspect lower connections from underneath.
• Verify cooling fans cycle on at normal operating temperature, confirming proper system function and thermostat operation.
• Check coolant level in expansion tank after test drive; level should remain at MAX/COLD FILL line when engine is cold.
• Monitor engine temperature gauge during test drive; temperature should remain in normal range (typically center of gauge) under normal driving conditions.
• Inspect ground beneath vehicle after overnight parking for any coolant drips indicating slow leaks.

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