🏷️ Basic Information

Make:

Mercedes-Benz

Model:

560 SEC

Body Style:

Coupé

Chassis Code:

C126

Generation Name:

Second Generation (W126/C126)

Generation Years:

1979-1991 (W126 Sedan) / 1981-1991 (C126 Coupé)

Engine Code Family:

M117

Specific Engine Variant:

M117.968

👋 Introduction

Segment:

Full-size Luxury Grand Tourer Coupé

Positioning:

Flagship, performance-oriented, elegantly styled luxury coupe representing the pinnacle of Mercedes-Benz engineering and design in the late 1980s.

Primary Competitors:

BMW 8 Series (E31 - later entrant), Jaguar XJS, Aston Martin Vantage Volante (V8), Rolls-Royce Corniche.

Design Philosophy:

Aerodynamic styling, robust construction, luxurious interior, advanced (for its time) engineering, and powerful V8 engine.

Target Audience:

Affluent individuals seeking a sophisticated, powerful, and comfortable grand touring vehicle with exceptional build quality and brand prestige.

📋 Manual Details

Covered Years:

1985, 1986, 1987, 1988, 1989, 1990, 1991

Regions Covered:

Global (factory specifications)

Estimated Page Count:

Extensive (specific count not provided, but implies full factory documentation)

Type:

Factory Service and Repair Manual

Language:

English (implied by product description and target market)

Format:

PDF Download

📖 Manual Coverage

Powertrain:

Engine mechanicals, fuel injection, ignition, cooling, exhaust, transmission (manual & automatic), clutch, transfer case (if applicable to specific 560 SEC variants, typically RWD).

Chassis:

Suspension (front/rear), steering, brakes (hydraulic, parking), wheels, tires, axles, driveshaft components.

Electrical:

12V system, battery, starting, charging, lighting, instrumentation, warning lamps, basic body electricals (door locks, power windows - implied).

Body & Interior:

Body structure inspection, water leakage, corrosion, lubrication points, door hinges, door locks, sunroof, soft top operation (if applicable), hood, windshield wipers/washers, antenna mast, headlamps, exterior lamps, mirrors, safety belts, backrest locks, noise encapsulation.

Climate Control:

Heating, ventilation, air conditioning (AC) refrigerant charge, dust filter, active charcoal filter, recirculating air filter.

Routine Maintenance:

Engine oil & filter change, air filter replacement, fuel filter replacement, V-belt inspection/replacement, spark plug service, coolant level & antifreeze check, poly V-belt inspection, fuel system condition check, battery fluid check, windshield washer fluid check.

Engine Tuning And Adjustment:

Valve clearance adjustment/checking, idle speed adjustment/checking, injection timing adjustment/checking, engine stop adjustment, re-torque engine mount bolts.

Transmission Service:

Manual transmission oil change, oil level check/correction; Automatic transmission fluid & filter change, fluid level check/correction; Transfer case fluid change, fluid level check/correction.

Brake System Service:

Brake fluid level check, line inspection, pad & disk thickness check, disk inspection/cleaning, parking brake cable adjustment, brake fluid replacement, parking brake check.

Suspension And Steering Service:

Suspension and body structure inspection, self-leveling suspension inspection, front axle oil level check, front axle ball joint check, ball joint check (special tool), steering play check, steering bolt re-tightening.

Body And Interior Maintenance:

Component condition inspection, lines & hoses inspection, water leakage & corrosion inspection, lubricating door hinges, door locks, sunroof rails, hood lubrication, cleaning water drains, lower noise encapsulation panel removal/installation, lower engine compartment panel removal/installation, body paint damage inspection.

Diagnostics And Troubleshooting:

Implied by 'same Repair Service manual your local dealer will use' and comprehensive coverage of all systems. Specific diagnostic procedures for M117 engine and associated ECUs (KE-Jetronic).

Depth:

Comprehensive factory-level detail, including diagnostic procedures, repair instructions, specifications, and torque values. Covers everything from basic maintenance to component replacement and system diagnostics.

📊 Manual Specifications

Format:

PDF

Searchability:

Fully searchable text

Printability:

All pages printable

Scan Quality:

Real files, not scans (high fidelity)

Binding:

Not applicable (Digital Download)

Paper Type:

Not applicable (Digital Download)

Bookmarking:

Completely bookmarked

⚙️ Engine Specifications

Engine Type:

Naturally Aspirated V8

Displacement:

5.6 Liters (5549 cc)

Bore X Stroke:

94.5 mm x 98.0 mm

Compression Ratio:

9.1:1

Engine Code:

M117.968

Horsepower:

237 hp (177 kW) @ 4750 rpm (US Spec)

Torque:

300 lb-ft (407 Nm) @ 3250 rpm (US Spec)

Fuel Delivery:

Bosch KE-Jetronic Mechanical Fuel Injection

Fuel Type:

Unleaded Premium Gasoline (91+ Octane)

Oil Type Recommendation:

API SF, ACEA A2 or equivalent (e.g., 15W-40, 10W-40, 5W-30 depending on climate and specific manufacturer approval - consult manual for precise MB-Approval specs)

Oil Capacity:

Approx. 7.5 Liters (with filter change)

Coolant Type Recommendation:

Mercedes-Benz Approved Antifreeze/Coolant (e.g., G48 or equivalent, 50/50 mix with distilled water)

Coolant Capacity:

Approx. 10.0 Liters

🔧 Transmission

Type:

4-Speed Automatic (722.3 Series)

Transmission Fluid Type:

Dexron III / Mercon (MB Spec 236.3 or equivalent)

Transmission Fluid Capacity:

Approx. 7.5 Liters (dry fill, varies with filter replacement)

Type:

Manual Transmission not offered on 560 SEC models.

Features:

Torque converter lock-up clutch for improved fuel efficiency.

📐 Dimensions

Length:

4950 mm (194.9 in)

Width:

1800 mm (70.9 in)

Height:

1390 mm (54.7 in)

Wheelbase:

2800 mm (110.2 in)

Curb Weight:

Approx. 1850 kg (4079 lbs)

Standard Wheel Size:

15 x 7J (often alloy 'Gullideckel' style)

Standard Tire Size:

205/65VR15

Wheel Bolt Pattern:

5x112

Tire Pressure Recommendation:

See manual for specific loads and speeds (typically around 30-35 PSI).

🛡️ Safety Features

Crash Test Data:

Limited official US crash test data available for this era and specific model. However, the W126 platform was known for its robust safety cage and passive safety features.

ABS:

Standard

Traction Control:

Not standard on early models, optional or standard on later 560 SEC variants (ASR - Anti-Slip Regulation may be present on late '89-'91 models).

Airbags:

Driver-side airbag standard from 1987 onwards. Passenger airbag optional.

Seatbelts:

3-point inertia reel seatbelts front and rear.

Structural Integrity:

Reinforced passenger cell, crumple zones.

💡 Technology Features

Audio System:

Factory premium sound system (Becker or Blaupunkt), often with cassette player. CD changers were often dealer-installed options.

Antenna:

Power antenna mast.

Cruise Control:

Standard

Level Control System:

Hydraulic Self-Leveling Suspension (SLS) standard on rear, optional on front (ADS - Automatic Differential Suspension). Covered in manual.

Connectivity Features:

Limited by modern standards. Primarily basic telecommunication (optional cellular phone integration in some models) and diagnostics via OBD I port.

Power Features:

Power windows, power seats (with memory), power mirrors, power steering, power antenna, power tilt/telescopic steering wheel (optional).

Convertible Top Mechanism:

Hydraulic operated convertible top mechanism (for SEC models, refers to sunroof operation, not a convertible). Soft top operation for other convertible models, but SEC is a hardtop coupé.

🔧 Maintenance

Oil And Filter Change:

Every 10,000-15,000 km (6,000-9,000 miles) or annually, whichever comes first. Consult manual for precise interval based on driving conditions.

Air Filter Replacement:

Every 30,000-50,000 km (20,000-30,000 miles) or as needed based on inspection.

Fuel Filter Replacement:

Every 50,000-75,000 km (30,000-45,000 miles).

Spark Plug Replacement:

Every 60,000-100,000 km (40,000-60,000 miles) depending on spark plug type (e.g., copper vs. platinum).

Coolant Replacement:

Every 3-5 years or 60,000-100,000 km (40,000-60,000 miles).

Transmission Fluid And Filter:

Every 60,000-100,000 km (40,000-60,000 miles) or as per manual recommendations.

Power Steering Fluid:

ATF Dexron II/III or MB Spec 236.3 (consult manual for exact specification).

Brake Fluid:

DOT 4 (Mercedes-Benz recommends MB Spec 331.0 or equivalent).

Common Problems:

Cylinder head gasket leaks, fuel distributor wear (KE-Jetronic), wiring harness degradation (especially insulation on specific engine sensors and loom), BECK/ETS (Engine Control Unit) failure, window regulator issues, climate control O-ring leaks, idle control valve issues, self-leveling suspension (SLS) component failure (accumulator, pump, hoses).

Preventative Maintenance Notes:

Regular inspection and replacement of vacuum hoses and wiring insulation are crucial. Thorough lubrication of sunroof tracks and door mechanisms is advised. Keep cooling system in top condition to prevent overheating.

📚 Vehicle History

Heritage:

Mercedes-Benz has a long-standing reputation for engineering excellence, luxury, and safety, established over decades of automotive innovation.

Predecessor:

380 SEC (C126)

Successor:

S600 Coupé (C140 - when the S-Class Coupé separated into its own model line).

Key Updates During Production:

Increased engine displacement from 5.0L (420/500 SEC) to 5.6L for the 560 SEC. Introduction of driver airbag (1987), optional passenger airbag, updated KE-Jetronic, and minor styling revisions.

Production Period For 560 Sec:

1985-1991

Manufacturing Location:

Germany (primarily Sindelfingen plant)

🏆 Awards & Recognition

General Recognition:

Consistently ranked among the top luxury cars of its era for build quality, comfort, and performance. Praised for its timeless design and engineering.

Reliability Perception:

Generally perceived as a very reliable vehicle with proper maintenance. However, complex systems can be costly to repair if neglected.

Manufacturer Certification:

This manual is the official factory documentation, equivalent to dealership-level service information.