🏷️ Basic Information

Make:

Mercedes-Benz

Model:

300E

Model Code:

W124 (E-Class)

Years Covered:

1990, 1991, 1992

Chassis Code:

W124.030

Engine Code:

M103.980

👋 Introduction

Market Position:

The Mercedes-Benz 300E (W124) represented the pinnacle of mid-size luxury sedans in its era, known for its build quality, durability, and sophisticated engineering. This manual caters to owners and technicians who value precision and longevity.

Competitive Analysis:

Competed against vehicles like the BMW 5 Series (E34), Audi 100, and Lexus LS 400. The W124 was often lauded for its superior ride comfort and build integrity compared to some rivals.

Key Features:

Robust chassis, advanced independent suspension, sophisticated M103 engine, optional advanced safety features like ABS, excellent interior comfort and ergonomics.

📋 Manual Details

Coverage Areas:

All mechanical and electrical systems, bodywork, specifications, maintenance, troubleshooting, repair procedures.

Page Count:

Approximately 1500+ pages (estimated, based on typical comprehensive manuals of this era)

Manual Type:

Factory Service Manual / Repair Manual

Language:

English

Format:

Digital (PDF likely, though original could be printed)

📖 Manual Coverage

Engine:

Engine mechanical, lubrication system, cooling system, fuel system (KE-Jetronic), ignition system, engine management (ECU), exhaust system.

Transmission:

4-speed Automatic Transmission (722.4 series) or 5-speed Manual Transmission (G5/27-5), including hydraulics, electronics, and shift control.

Drivetrain:

Rear-wheel drive, driveshaft, differential, axle shafts.

Suspension:

Front and rear suspension components, springs, shock absorbers, control arms, bushings, anti-roll bars.

Steering:

Power steering system, steering column, steering gear.

Brakes:

Front and rear disc brakes, ABS (Anti-lock Braking System), brake fluid, hydraulic lines, parking brake.

Electrical:

Battery, charging system, starter motor, lighting system, wipers, horn, power windows, power seats, central locking, instrument cluster, wiring diagrams for all circuits.

HVAC:

Heating, ventilation, and air conditioning system, climate control components.

Body:

Body panels, doors, windows, trim, interior components, body sealing.

Procedures Included:

Regular maintenance, scheduled maintenance, inspections, component removal and installation, adjustment procedures, diagnostic troubleshooting flowcharts, wiring harness repair, engine rebuild procedures, transmission overhaul, clutch replacement (manual), brake bleeding and repair, suspension component replacement, steering system service.

Engine Management Diagnostics:

Detailed troubleshooting for KE-Jetronic system, including idle control, cold start enrichment, and sensor testing. Diagnostic flowcharts for engine performance issues.

Electrical Troubleshooting:

Extensive wiring diagrams for all vehicle circuits, with component location guides and diagnostic methods for electrical faults.

Chassis Diagnostics:

Procedures for checking wheel bearings, steering linkage play, suspension component wear, and alignment specifications.

Technical Depth:

Comprehensive: Covers basic maintenance to full engine and transmission overhauls, including detailed diagnostic procedures and wiring diagrams. Suitable for professional mechanics and advanced DIY enthusiasts.

📊 Manual Specifications

File Format:

PDF (typically searchable and bookmarkable)

Print Quality:

High resolution for clear diagrams and text (when printed).

Binding Type:

Not applicable for digital format, but original factory manuals were typically bound or sectioned.

Paper Type:

Not applicable for digital format, but original factory manuals used durable, high-quality paper.

⚙️ Engine Specifications

Engine Type:

Inline 6-Cylinder, Naturally Aspirated

Engine Displacement:

2.6 Liters (2599 cc)

Engine Code:

M103.980

Bore X Stroke:

82.0 mm x 80.5 mm

Compression Ratio:

9.2:1

Horsepower:

160 hp (118 kW) @ 5500 rpm (approximate, may vary slightly by market)

Torque:

177 lb-ft (240 Nm) @ 4400 rpm (approximate)

Fuel Delivery:

Bosch KE-Jetronic Electronic Fuel Injection with Lambda control

Fuel Type:

Unleaded Premium Gasoline (91+ Octane)

ECM Type:

Bosch Motronic (specific variant dependent on year/market, e.g., ME2.0)

Coolant Capacity:

Approximately 8.5 Liters (8.9 US quarts)

Oil Capacity:

7.5 Liters (7.9 US quarts) with filter change

Recommended Oil Viscosity:

SAE 10W-30 or 10W-40 (API SG or higher)

🔧 Transmission

Transmission Type:

4-Speed Automatic (Model 722.4)

Transmission Type:

5-Speed Manual (Model G5/27-5)

Automatic Features:

Lock-up torque converter, electronic/hydraulic control for shifting.

Transmission Fluid Type:

MB 236.3 (e.g., ATF Dextron II)

Transmission Fluid Capacity:

Approximately 7.0 Liters (7.4 US quarts) for overhaul, 3.5 Liters for fluid change.

Transmission Fluid Type:

MB 235.1 (e.g., SAE 75W-80 or 75W-90 GL-4)

Transmission Fluid Capacity:

Approximately 1.7 Liters (1.8 US quarts)

📐 Dimensions

Length:

188.2 in (4780 mm)

Width:

69.5 in (1765 mm)

Height:

55.7 in (1415 mm)

Wheelbase:

110.2 in (2800 mm)

Front Track:

58.6 in (1488 mm)

Rear Track:

57.3 in (1455 mm)

Curb Weight:

Approximately 3460 lbs (1569 kg)

Gross Vehicle Weight Rating:

Approximately 4630 lbs (2100 kg)

Trunk Volume:

18.0 cu ft (510 L)

🛡️ Safety Features

NHTSA Frontal Impact:

Not directly rated by NHTSA in the modern sense for these years, but known for robust construction.

ABS:

Standard (Bosch ABS III)

Traction Control:

Optional (ASR - Acceleration Skid Control) on some models/markets.

Airbags:

Driver's side airbag optional initially, became more common in later W124 variants, but often not standard on 300E of this period.

Seatbelts:

3-point inertia-reel seatbelts with front pre-tensioners.

Body Construction:

High-strength steel safety cage construction, crumple zones.

💡 Technology Features

Infotainment System:

Basic Analog AM/FM Radio, optional Cassette Player. Some models may have had early CD players or premium sound systems.

Climate Control:

Manual Climate Control or optional Automatic Climate Control (ACC).

Cruise Control:

Standard

ABS:

Standard

Connectivity:

No modern connectivity features (Bluetooth, USB, etc.). Antennas are for radio reception.

🔧 Maintenance

Oil Change Interval:

Every 7,500 to 10,000 miles (12,000 to 16,000 km) or 12 months, whichever comes first (using quality synthetic oil).

Air Filter Replacement:

Every 15,000 to 20,000 miles (24,000 to 32,000 km)

Fuel Filter Replacement:

Every 30,000 miles (48,000 km)

Spark Plug Replacement:

Every 30,000 miles (48,000 km) (using correct type, e.g., Bosch W8DC or equivalent)

Transmission Fluid Change:

Every 30,000 to 40,000 miles (48,000 to 64,000 km)

Coolant Type:

Mercedes-Benz Specification 325.0 (Blue/Green Ethylene Glycol)

Brake Fluid Type:

DOT 3 or DOT 4

Known Issues:

Harness insulation degradation (common on many Mercedes of this era), vacuum line leaks affecting engine performance and central locking, timing chain stretch (though M103 is generally robust), potential for front suspension wear (ball joints, bushings), water pump and thermostat failures, KE-Jetronic issues due to age/gumming.

Preventative Maintenance Focus:

Regular inspection and replacement of all rubber hoses and vacuum lines, monitoring for oil leaks, diligent attention to cooling system maintenance.

📚 Vehicle History

Brand Heritage:

Mercedes-Benz has a long-standing reputation for engineering excellence, safety, and luxury vehicles dating back to the late 19th century. This lineage instilled confidence in the build quality of the W124.

Model Evolution:

The W124 generation (1984-1995) was the successor to the W123 and was a significant evolution, introducing more aerodynamic styling, advanced multi-link rear suspension, and a wider range of engine options. The 300E became a benchmark luxury sedan.

Production Years:

1984-1995 (W124 generation)

Manufacturing Locations:

Germany, South Africa, Mexico, Egypt.

🏆 Awards & Recognition

Recognitions:

The W124 generation consistently received accolades for its build quality, durability, and refinement, often cited in automotive press as a benchmark for luxury sedans of its time. It was widely considered one of the best-engineered cars of the 1980s and early 1990s.

Safety Ratings:

Praised for its robust safety engineering and crashworthiness relative to its peers, though formal modern testing standards were different.