Radiator

Complete radiator replacement procedure for the 2007-2013 Mercedes-Benz S65 AMG with M275 6.0L BiTurbo V12 engine, including coolant system drainage, component removal, and refill with proper bleeding.

Warnings

Tools required

Parts

• Radiator assembly × 1 — Use OEM Mercedes-Benz specification
• Upper radiator hose × 1 — Inspect and replace if deteriorated
• Lower radiator hose × 1 — Inspect and replace if deteriorated
• Radiator mount bushings/brackets × 1 — Often included with radiator
• Hose clamps (assorted) × 6 — OEM spring clamps or worm-drive
• Transmission cooler line O-rings × 2 — If equipped with quick-disconnect fittings
• Coolant expansion tank cap × 1 — Inspect and replace if over 5 years old

Fluids

• Mercedes-Benz Coolant (Blue) — 18 qt

Preparation

1. Ensure engine is completely cold (minimum 3 hours after last operation)
2. Park vehicle on level surface and engage parking brake
3. Disconnect negative battery terminal and wait 10 minutes for system capacitors to discharge
4. Raise vehicle and secure on jack stands at proper lift points
5. Remove engine undertrays and belly pans using T30 Torx driver
6. Place large drain pan beneath radiator drain location
7. Take photos of all hose routing and electrical connections for reference during reassembly

Procedure

1. 1

   Drain cooling system
   Slowly open coolant expansion tank cap to release any residual pressure. Locate radiator drain petcock on driver side lower tank. Attach drain hose if available, then open petcock carefully by hand to drain coolant into pan. Once drained, remove lower radiator hose at radiator connection for complete drainage.
   Torque spec

   Drain Petcock5 Nm (4 lb-ft)
2. 2

   Remove air intake components
   Remove engine cover by pulling upward on front edge then lifting. Disconnect mass airflow sensor connectors on both air intake tubes. Loosen hose clamps and remove both air intake tubes from throttle bodies to air filter housings. Remove air filter housing assemblies to gain access to radiator area. Label all vacuum lines before disconnecting.
   Torque spec

   Upper/Lower Hose Clamps3 Nm (2 lb-ft)
3. 3

   Disconnect cooling fan assembly
   Disconnect electrical connector from viscous fan clutch if equipped, or disconnect electrical connectors from both electric cooling fans. Remove fan shroud mounting bolts using 10mm socket. The M275 engine uses a large dual fan assembly - carefully lift fan assembly upward and out of engine bay, taking care not to damage radiator fins or fan blades.
   ⚠Fan assembly is heavy and awkward to remove. Have an assistant help or use engine support strap to prevent dropping into radiator.
4. 4

   Disconnect transmission cooler lines
   Locate transmission cooler lines at lower right side of radiator. Clean area around fittings thoroughly. Using appropriate flare nut wrench, carefully loosen transmission cooler line fittings. Have rags ready to catch residual ATF. Cap open lines immediately to prevent contamination. If equipped with quick-disconnect fittings, depress locking tabs and pull lines straight out.
   ⚠Do not use standard open-end wrenches on transmission line fittings as this will round off the soft brass fittings.
   Torque spec

   Transmission Cooler Lines25 Nm (18 lb-ft)
5. 5

   Disconnect radiator hoses
   Using hose clamp pliers, compress and slide spring clamps back on upper radiator hose at both radiator and thermostat housing connections. Twist hose gently to break seal, then pull off. Repeat for lower radiator hose. If hoses are stuck, use razor blade to carefully cut hose at radiator connection rather than risk damaging radiator neck.
   Torque spec

   Upper/Lower Hose Clamps3 Nm (2 lb-ft)
6. 6

   Disconnect auxiliary coolant lines
   Identify and disconnect smaller auxiliary coolant lines to radiator, including lines to coolant expansion tank and turbocharger cooling circuits. The M275 has multiple small diameter coolant lines - document routing with photos. Use hose clamp pliers to release clamps and carefully remove hoses.
   Torque spec

   Upper/Lower Hose Clamps3 Nm (2 lb-ft)
7. 7

   Remove radiator mounting hardware
   Locate radiator mounting bolts at top corners and bottom mount points. Remove upper radiator support brackets using 13mm socket. Remove lower radiator mounting bolts securing radiator to frame rails. The M275 radiator has plastic mounting tabs - inspect for cracks before reuse.
   ⚠Do not overtighten plastic mounting hardware during reassembly as specified torque prevents stress cracking.
   Torque spec

   Radiator Mount Bolts12 Nm (9 lb-ft)
8. 8

   Remove radiator from vehicle
   With all connections and mounts removed, carefully tilt top of radiator toward engine and lift radiator assembly upward and out of engine bay. The radiator is large and heavy - work carefully to avoid damaging condenser fins behind it or surrounding components. Inspect condenser for damage while radiator is removed.
   ℹ️This is an excellent opportunity to inspect AC condenser, replace coolant hoses, and clean debris from cooling stack.
9. 9

   Prepare and install new radiator
   Transfer any brackets or sensors from old radiator to new unit if not included. Install new rubber mounting bushings. Inspect transmission cooler ports and install new O-rings if equipped with quick-disconnect fittings. Carefully lower new radiator into position, ensuring it seats properly on lower mounts and aligns with upper brackets.
   Torque spec

   Radiator Mount Bolts12 Nm (9 lb-ft)
10. 10

    Reconnect all hoses and lines
    Install new lower and upper radiator hoses with new clamps, ensuring hoses are fully seated on radiator necks before tightening. Reconnect all auxiliary coolant lines in reverse order of removal using photos for reference. Reconnect transmission cooler lines, torquing fittings to specification. Install new clamps on all hose connections.
    Torque spec

    Upper/Lower Hose Clamps3 Nm (2 lb-ft)

    Transmission Cooler Lines25 Nm (18 lb-ft)
11. 11

    Reinstall cooling fan and air intake
    Carefully lower fan shroud assembly back into position, ensuring fan blades center properly in shroud and clear radiator. Install and torque mounting bolts. Reconnect fan electrical connectors. Reinstall air filter housings, intake tubes, and reconnect MAF sensors. Reinstall engine cover.
    Torque spec

    Upper/Lower Hose Clamps3 Nm (2 lb-ft)
12. 12

    Fill and bleed cooling system
    Close radiator drain petcock hand-tight. Mix Mercedes-Benz blue coolant 50/50 with distilled water or use pre-mixed coolant. Fill cooling system through expansion tank slowly to prevent air pockets. The M275 requires specific bleeding procedure: Start engine and run at 2000 RPM for 2 minutes, then idle. Add coolant as level drops. Repeat until coolant level stabilizes and both turbocharger coolant lines are warm, indicating flow through complete system. Install expansion tank cap.
    ⚠️Monitor temperature gauge constantly during bleeding. If temperature exceeds normal range, shut down immediately and allow to cool before continuing.
    Torque spec

    Drain Petcock5 Nm (4 lb-ft)
13. 13

    Perform system verification
    Using Star Diagnostic Tool, clear any coolant temperature-related fault codes. Run engine through full heat cycle (cold to operating temperature to cooling fan activation). Check all connections for leaks while engine is running. Verify both cooling fans activate properly. After cool-down, recheck coolant level and top off as needed. Check transmission fluid level if equipped with automatic transmission.
    ℹ️Coolant level will continue to drop as air bleeds out over first few drive cycles. Recheck level after 50 miles and top off as needed.

Reassembly

1. Reinstall all undertrays and belly pans with proper fasteners
2. Reconnect battery negative terminal and initialize window and sunroof positions using switch auto-up/down function
3. Reset service indicators if performing this as scheduled maintenance
4. Document repair with date and mileage for maintenance records

Verification

• Start engine and verify no coolant leaks at radiator connections, hoses, or transmission cooler lines
• Verify both cooling fans activate when engine reaches operating temperature
• Use Star Diagnostic Tool to verify no coolant system fault codes present
• Check coolant expansion tank level with engine cold - should be at COLD mark
• Verify transmission fluid level is correct if cooler lines were disconnected
• Test drive vehicle and monitor temperature gauge stays in normal range under load
• Perform pressure test of cooling system to 1.4 bar (20 psi) and verify holds pressure for 10 minutes
• Recheck all connections after first heat cycle and verify no seepage or staining

More procedures for this vehicle