Power Steering Hose - Return

Replace the power steering return hose on a 2007-2013 Mercedes-Benz S65 AMG with M275 6.0L BiTurbo engine, including fluid drainage, hose removal, installation with new O-rings, and system refill.

Warnings

Tools required

Parts

• Power steering return hose × 1 — A 221 466 13 82 or equivalent OEM
• Power steering line O-rings × 2 — Use OEM specification
• Hose clamps (if applicable) × 2 — Use OEM specification

Fluids

• Pentosin CHF 11S — 1.5 qt

Preparation

1. Ensure engine is cold or has cooled for at least 30 minutes
2. Park vehicle on level surface and engage parking brake
3. Remove engine cover by loosening cover screws (if installed)
4. Place protective covers over fenders to prevent fluid damage
5. Position drain pan and fluid catch containers under work area
6. Locate power steering reservoir on driver side of engine bay

Procedure

1. 1

   Extract fluid from reservoir
   Use a turkey baster or fluid extractor to remove as much power steering fluid as possible from the reservoir. This minimizes spillage during hose disconnection. Extract fluid into a clean container and note the fluid condition and level.
2. 2

   Raise and support vehicle front
   Lift the front of the vehicle using a floor jack at the designated front jacking point. Support on jack stands placed at the reinforced pinch weld locations. Ensure vehicle is stable before proceeding underneath. This provides access to the lower routing of the return hose.
   ⚠️Never work under a vehicle supported only by a jack. Always use rated jack stands.
3. 3

   Trace return hose routing
   Identify the complete path of the power steering return hose from the steering rack to the reservoir. The return hose is the lower pressure line and typically has a larger diameter than the pressure line. Note any clips, brackets, or routing guides securing the hose. On the M275 engine, the hose routes around the left side turbocharger.
4. 4

   Remove reservoir end connection
   Position drain pan directly below the reservoir connection point. If using a clamp connection, use hose clamp pliers to compress and slide the clamp away from the fitting. If using a threaded fitting, use a line wrench to loosen the connection. Once loosened, pull the hose from the reservoir and allow remaining fluid to drain into the pan. Cap or plug the reservoir opening to prevent contamination.
5. 5

   Disconnect steering rack end
   Working from underneath the vehicle, locate where the return hose connects to the steering rack on the passenger side. Position drain pan to catch residual fluid. Use a line wrench to loosen the threaded fitting at the rack. Once loose, carefully thread the fitting off by hand and allow fluid to drain completely. Inspect the old O-ring and note its condition.
   ℹ️Some fluid will continue to drain from the rack even after initial flow stops. Allow adequate draining time.
6. 6

   Remove hose from routing clips
   Release the return hose from all mounting clips, brackets, and routing guides along its path. On the S65 AMG, pay special attention to heat shields and ensure the hose clears turbocharger components. Note the exact routing and clip positions for proper reinstallation. Remove the old hose from the vehicle.
7. 7

   Prepare new hose and O-rings
   Unpack the new power steering return hose and verify it matches the original routing and length. Install new O-rings on both connection ends of the new hose. Lightly lubricate the O-rings with clean Pentosin CHF 11S power steering fluid to ease installation and prevent damage during threading.
8. 8

   Install hose to steering rack
   Begin installation from the steering rack end. Route the new hose following the exact path noted during removal, ensuring clearance from turbocharger, exhaust components, and sharp edges. Thread the fitting onto the steering rack by hand to prevent cross-threading. Once hand-tight, use a line wrench and torque wrench to tighten to specification.
   ⚠Always start threaded fittings by hand. Cross-threading will damage the rack and require expensive repairs.
   Torque spec

   Power Steering Line Fittings30 Nm (22 lb-ft)
9. 9

   Secure hose routing and connect to reservoir
   Working from the rack toward the reservoir, secure the hose in all original mounting clips and brackets. Verify proper clearance throughout the routing path, especially near heat sources. Connect the reservoir end of the hose. If using a clamp connection, ensure the hose is fully seated on the barb and position the clamp over the barb area, then tighten securely. If threaded, torque to specification.
   Torque spec

   Power Steering Line Fittings30 Nm (22 lb-ft)
10. 10

    Fill power steering system
    Remove the reservoir cap and fill with fresh Pentosin CHF 11S fluid to the COLD MAX mark. Start the engine and allow it to idle. Turn the steering wheel slowly from lock to lock 10-15 times without holding at full lock. Check fluid level and add as necessary. Fluid level will drop as air is purged from the system.
    ℹ️Do not hold steering wheel at full lock for more than 5 seconds to prevent overheating the pump.
11. 11

    Bleed system and check for leaks
    With engine running at idle, continue turning steering wheel lock to lock until no more bubbles appear in the reservoir and the fluid level stabilizes. Check all connection points for leaks, particularly at the rack and reservoir fittings. Wipe all connections clean with a shop towel and inspect for fresh fluid seepage. Top off reservoir to the HOT MAX mark once system reaches operating temperature.
12. 12

    Lower vehicle and final inspection
    Turn off engine and lower vehicle from jack stands. Reinstall engine cover and tighten cover screws to specification. Start engine one final time and verify smooth power steering operation without noise or leaks. Check fluid level when cold after the vehicle has sat for several hours.
    Torque spec

    Cover Screws15 Nm (11 lb-ft)

Reassembly

1. Ensure all hose routing clips are secured to prevent hose contact with hot exhaust or moving components
2. Verify fluid level is at COLD MAX mark when engine is cold, HOT MAX when at operating temperature
3. Double-check all connection points are torqued to specification and show no signs of leakage
4. Dispose of used power steering fluid according to local environmental regulations

Verification

• Start engine and verify power steering operates smoothly without unusual noise or excessive effort
• Turn steering wheel lock to lock several times and confirm no whining, groaning, or cavitation sounds
• Inspect all connection points for fluid leaks with engine running and steering in motion
• Check power steering fluid level in reservoir - should be at HOT MAX when warm, COLD MAX when cold
• Verify no fluid drips under vehicle after test drive and overnight parking
• Confirm steering response is immediate and consistent throughout the full range of motion
• Check that hose routing has adequate clearance from all hot components (turbochargers, exhaust manifolds)

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