🏷️ Basic Information

Make:

Mercedes-Benz

Model:

300E / E320

Chassis Code:

W124

Model Years Covered:

1986-1995

Engine Codes 300E:

M103 (3.0L Inline-6)

Engine Codes 320E:

M104 (3.2L Inline-6)

👋 Introduction

Segment:

Executive Sedan (mid-size luxury)

Target Audience:

Affluent professionals, discerning car owners valuing build quality, comfort, and engineering.

Key Competitors:

BMW 5 Series (E34), Audi 100/A6 (C3/C4), Lexus LS400, Jaguar XJ.

Engineering Philosophy:

Over-engineered, durable, comfort-focused, refined driving experience.

Dvp Strategy:

Focus on longevity, robust construction, and sophisticated yet reliable mechanical systems, especially regarding the powertrain and chassis.

📋 Manual Details

Major Systems Covered:

Engine mechanical, engine fuel, engine electrical, powertrain management, transmission, chassis, suspension, steering, brakes, climate control, body electrical, interior, exterior.

Estimated Page Count:

Thousands (typical factory service manuals are extensive)

Type:

Factory Service Workshop Manual

Language:

English

Delivery Format:

Digital (HTML/Flash menu with PDF files)

📖 Manual Coverage

Engine Mechanical:

Complete teardown and reassembly procedures for M103 and M104 engines, including cylinder head, block, pistons, crankshaft, camshafts, timing components.

Engine Fuel System:

Diagnosis and repair of Bosch KE-Jetronic (CIS-E) fuel injection systems, fuel pumps, injectors, fuel pressure regulators, and air flow meter.

Engine Electrical:

Ignition system diagnosis, starter, alternator, battery, wiring diagrams, component testing.

Transmission:

Automatic transmission (e.g., 722.3, 722.4, 722.5) service and repair, including hydraulic control, valve body, torque converter, fluid changes, and internal component overhauls.

Brakes:

ABS (Anti-lock Braking System) diagnosis and repair, brake fluid flush, caliper and rotor replacement, parking brake service.

Suspension:

Front and rear suspension component replacement (struts, shocks, control arms, bushings), alignment specifications.

Steering:

Power steering system diagnosis and repair, steering gear service, tie rod ends, steering linkage.

Climate Control:

HVAC system service, R134a refrigerant handling, compressor, condenser, evaporator, heater core, blower motor, control panel diagnosis.

Body Electrical:

Lighting systems, power windows, power seats, central locking, instrument cluster, wiper system, cruise control, wiring schematics.

Interior Trim:

Removal and installation procedures for interior panels, seats, dashboard components, headliner, and trim pieces.

Exterior Trim:

Removal and installation of bumpers, fenders, hood, trunk lid, grille, door panels, and trim moldings.

Maintenance Procedures:

Oil and filter changes, spark plug replacement, air filter replacement, fuel filter replacement, coolant flush, brake fluid flush, transmission fluid and filter change, differential fluid change.

Repair Procedures:

Engine rebuilds, transmission overhauls, cylinder head gasket replacement, brake caliper rebuild, suspension component replacement, starter and alternator replacement, fuel pump replacement, radiator replacement.

Troubleshooting Diagnostics:

Systematic diagnostic procedures for common and complex issues, fault code interpretation (if applicable to the system), symptom-based troubleshooting guides.

Technical Specifications Data:

Torque specifications, fluid capacities and types, diagnostic parameters, electrical resistance values, component clearances.

Depth:

Comprehensive from basic DIY maintenance to complete engine and transmission rebuilds, suitable for professional technicians and advanced DIY enthusiasts.

📊 Manual Specifications

Digital Format:

HTML/Flash menu with integrated PDF documents

Digital Quality:

High-resolution, searchable PDFs with clear diagrams and illustrations.

Digital Binding:

N/A (Digital format)

Digital Paper Type:

N/A (Digital format)

⚙️ Engine Specifications

Engine Type:

Naturally aspirated inline-6 cylinder, SOHC

Displacement 300E:

2.6 Liters (for early models) / 3.0 Liters (M103.980)

Bore X Stroke 300E:

82.0 mm x 94.5 mm (M103)

Compression Ratio 300E:

9.2:1 (M103)

Horsepower 300E:

188 hp @ 5,700 rpm (M103.980)

Torque 300E:

207 lb-ft @ 4,400 rpm (M103.980)

Engine Type:

Naturally aspirated inline-6 cylinder, DOHC (4 valves per cylinder)

Displacement 320E:

3.2 Liters (M104.992)

Bore X Stroke 320E:

89.9 mm x 84.0 mm (M104)

Compression Ratio 320E:

10.0:1 (M104)

Horsepower 320E:

217 hp @ 5,500 rpm (M104.992)

Torque 320E:

228 lb-ft @ 4,000 rpm (M104.992)

0 60 Mph 300E:

approx. 8.2 seconds

0 60 Mph 320E:

approx. 7.0 seconds

Injection Type:

Bosch KE-Jetronic (CIS-E) for M103, Bosch HFM (Hot Film Mass Airflow) or KE-Jetronic for M104 depending on year/market.

Fuel Type:

Unleaded gasoline

Fuel Octane Requirement:

Premium (91+ octane recommended)

🔧 Transmission

Type Early Models:

4-speed automatic (e.g., 722.3)

Type Later Models:

5-speed automatic (e.g., 722.4, 722.5 with electronic control)

Manual Transmission Availability:

Rarely offered in US market for 300E/E320, but available in some markets/variants.

Shift Modes:

Standard (S) and Economy (E) modes (on some automatic transmissions)

Automatic Transmission Fluid Type:

MB 236.1 or 236.2 (ATF Dexron II or equivalent, refer to specific model year manual for exact spec)

📐 Dimensions

Length:

approx. 188.0 inches (4775 mm)

Width:

approx. 69.1 inches (1755 mm)

Height:

approx. 56.1 inches (1425 mm)

Wheelbase:

approx. 110.2 inches (2800 mm)

Curb Weight:

approx. 3,400 - 3,600 lbs (1540 - 1630 kg), varies by model and options

🛡️ Safety Features

NHTSA Front Impact Rating:

5-star (for models equipped with airbags, although airbags became standard later in the production run)

ABS:

Standard on most models from mid-production onwards.

Traction Control:

Optional or standard on later models (e.g., ASR - Acceleration Skid Regulation).

Airbags:

Driver-side airbag standard on later models, optional on earlier ones. Passenger airbag available on later models.

Seatbelts:

3-point inertia-reel seatbelts front and rear.

💡 Technology Features

Audio System:

Original systems were typically AM/FM cassette players with optional CD changers and premium sound systems (e.g., Becker).

Cruise Control:

Standard on most models.

Climate Control System:

Optional automatic climate control (Thermatic/Thermotronic) offering precise temperature management.

Original Connectivity:

Limited to factory-installed options like car phones (rare in earlier years).

🔧 Maintenance

Oil Change Interval:

Every 7,500 to 10,000 miles or 12 months (refer to manual for exact recommendations and oil type).

Spark Plug Replacement Interval:

Approximately 30,000 miles for standard plugs; longer life for iridium/platinum plugs if factory-equipped.

Air Filter Replacement Interval:

Every 15,000 to 30,000 miles or as needed based on driving conditions.

Coolant Flush Interval:

Every 2-3 years or 30,000-50,000 miles (using MB-approved coolant).

Transmission Fluid And Filter Change Interval:

Typically every 30,000 to 50,000 miles (critical for longevity of these transmissions).

Engine Oil Specification:

API SJ/SL or approved MB 229.1, 229.3. Viscosity typically 10W-40 or 15W-40, but consult manual for precise recommendations based on climate and engine type.

Coolant Specification:

MB 325.0 (Glysantin G48 or equivalent, typically blue/green ethylene glycol-based).

Brake Fluid Specification:

DOT 4

Wiring Harness Degradation:

Engine wiring harnesses (specifically insulation) can become brittle and degrade over time, leading to various electrical issues. Early models (pre-1992) are more prone to this.

Head Gasket Leaks:

While generally robust, head gasket issues can arise, particularly with age and mileage, especially on M104 engines if overheated.

Oil Cooler Seals:

Leaking oil cooler seals can lead to oil in the coolant or coolant in the oil.

Transmission Reliability:

While durable, the automatic transmissions require strict adherence to fluid change intervals. Neglect can lead to premature wear and expensive repairs.

Window Regulator Failure:

Power window regulators can fail due to plastic component wear.

📚 Vehicle History

Marque Reputation:

Renowned for engineering excellence, build quality, durability, and luxury.

W124 Introduction:

The W124 chassis debuted in 1984 (as the 300TD) and the sedan variants (300E, 300D) in 1985. The models covered by this manual (300E and 320E) represent key gasoline engine options within this highly successful generation.

Facelifts:

The W124 received significant updates, including exterior styling refinements (e.g., body-colored lower panels, updated grille, clear headlight lenses) and interior enhancements, particularly a facelift in 1993 that introduced the 'E-Class' badging and further modernized the design.

Production Period:

1985-1995 for sedans

Manufacturing Locations:

Germany (Sindelfingen)

🏆 Awards & Recognition

Car And Driver 10 Best:

The W124 chassis was frequently recognized by automotive publications like Car and Driver, often appearing on their annual '10 Best' lists for its blend of luxury, performance, and build quality.

Safety Certifications:

Adhered to rigorous German and international safety standards of the era, contributing to its reputation for occupant protection.