|
Introduction
|
|
Market Position
|
|
Vehicle Segment:
|
Mid-size luxury executive sedan/estate, renowned for its robust engineering, comfort, and durability.
|
|
Competitive Analysis
|
|
Key Competitors Era:
|
BMW 5 Series (E28), Audi 100, Volvo 240/740, Jaguar XJ, American luxury sedans (e.g., Cadillac DeVille).
|
|
Key Features
|
|
Vehicle Strengths:
|
Exceptional build quality, legendary reliability (especially diesel engines), comfortable ride, sophisticated engineering for its time, spacious interior.
|
|
Manual Value Proposition:
|
Provides expert-level guidance for maintaining and repairing a classic Mercedes-Benz, crucial for preserving its value and functionality. The 'A-Z' and 'dealer technician' claims highlight its comprehensiveness and authority.
|
|
Manual Coverage
|
|
Systems Covered
|
|
Engine Systems:
|
Engine mechanical (cylinder head, block, pistons, crankshaft), fuel delivery (carburetor/injection), ignition system, cooling system, lubrication system, emissions control systems.
|
|
Drivetrain Systems:
|
Clutch (if manual), automatic transmission (torque converter, valve body, rebuild procedures), differential, driveshafts, axles.
|
|
Suspension Steering:
|
Front suspension (struts, control arms, ball joints), rear suspension (multi-link, trailing arms), steering gear, power steering system, wheel alignment specifications.
|
|
Braking System:
|
Hydraulic system (master cylinder, brake lines, calipers/wheel cylinders), parking brake, Anti-lock Braking System (ABS) if equipped, brake pad/disc specifications, bleeding procedures.
|
|
Electrical System:
|
Battery, charging system (alternator), starting system (starter motor), lighting system, instrumentation, dashboard controls, wiring diagrams (crucial for this era), fuse/relay assignments.
|
|
Body Chassis:
|
Body panels, doors, hinges, locks, glass, interior trim, seat adjustments, chassis components, jacking points, body repair specifications.
|
|
HVAC System:
|
Heating, ventilation, and air conditioning (compressor, condenser, evaporator, refrigerant recharge, controls).
|
|
Procedures Included
|
|
Maintenance Procedures:
|
Oil changes, filter replacements, spark plug replacement, coolant flushes, belt inspections/replacement, brake fluid changes, air filter replacement, scheduled servicing.
|
|
Diagnostic Procedures:
|
Troubleshooting guides for common issues, symptom-based diagnostics, component testing procedures (e.g., fuel pressure, ignition timing, compression tests), wiring diagnostic techniques.
|
|
Repair Procedures:
|
Engine tune-ups, carburetor/fuel injection system overhaul, brake caliper/rotor replacement, suspension component replacement, transmission fluid service and repair, electrical component replacement, body panel repair.
|
|
Rebuild Procedures:
|
Likely includes detailed procedures for engine rebuilds (e.g., cylinder head gasket replacement, piston ring replacement), transmission overhauls, and component rebuilds.
|
|
Technical Data Tables:
|
Torque specifications for critical fasteners, valve clearance settings, ignition timing settings, fluid capacities, diagnostic trouble code (DTC) interpretations (if applicable).
|
|
Technical Depth
|
|
Diagnostic Capability:
|
Advanced diagnostics, including component testing, electrical circuit analysis, and troubleshooting for complex system failures.
|
|
Repair Complexity:
|
Covers everything from basic preventative maintenance to complete engine and transmission rebuilds, suitable for professional technicians and experienced DIYers.
|
|
Specificity:
|
Vehicle-specific, not generic. This is the same manual used by dealership technicians.
|
|
Engine Specifications
|
|
Primary Engine
|
|
Engine Options 1986:
|
For 1986, the W123 likely featured updated versions of: M102 gasoline inline-4 (2.0L, 2.3L) and M103 inline-6 (2.6L, 3.0L). Diesel options included OM615 (2.0L diesel), OM616 (2.4L diesel), and OM617 (3.0L diesel, often turbocharged). The 'E' designation typically denotes fuel injection.
|
|
Performance
|
|
Typical Horsepower Range:
|
Gasoline: 90-130 hp (naturally aspirated), 150-180 hp (fuel-injected/turbocharged). Diesel: 60-80 hp (naturally aspirated), 90-125 hp (turbocharged).
|
|
Typical Torque Range:
|
Gasoline: 110-150 lb-ft. Diesel: 90-120 lb-ft (naturally aspirated), 120-160 lb-ft (turbocharged).
|
|
Fuel System
|
|
Fuel Injection Gasoline:
|
Likely Bosch K-Jetronic (CIS) mechanical fuel injection for gasoline models, especially the 'E' variants.
|
|
Fuel System Diesel:
|
Bosch inline injection pump for diesel engines, often with indirect injection.
|
|
Cooling System
|
|
Coolant Type:
|
Mercedes-Benz recommends G48 ethylene glycol coolant (blue/green color), typically a 50/50 mix with distilled water. The manual will specify the exact MB specification.
|
|
Lubrication System
|
|
Engine Oil Specifications:
|
Likely API SF or SG rated oils, viscosity grades like 10W-30, 10W-40, or 15W-40 depending on climate and specific engine. Manual will confirm exact MB 22x.xx specifications.
|
|
Oil Capacity:
|
Typically 5-7 liters (5.3-7.4 US quarts) depending on engine size. Manual will provide exact capacities.
|
|
Transmission
|
|
Standard
|
|
Transmission Options Standard:
|
Many W123 models came standard with a 4-speed or 5-speed manual transmission.
|
|
Optional
|
|
Transmission Options Optional:
|
A 4-speed or 5-speed automatic transmission (often referred to as 4G-Tronic or 5G-Tronic for later models, though W123 may have earlier designations) was a popular option.
|
|
Features
|
|
Automatic Transmission Features:
|
Torque converter lock-up, hydraulic control, neutral safety switch.
|
|
Fluid Specifications
|
|
Automatic Transmission Fluid:
|
Likely MB-specific ATF specification, often DEXRON II or equivalent for this era. The manual will provide the precise MB part number or specification.
|
|
Manual Transmission Fluid:
|
Gear oil, likely GL-4 specification, with appropriate viscosity grade (e.g., 75W-90). Manual will specify.
|
|
Maintenance
|
|
Service Intervals
|
|
Oil Change Interval:
|
Typically every 5,000 to 10,000 miles (8,000 to 16,000 km) or annually, depending on driving conditions. Manual will specify based on oil type and driving usage.
|
|
Major Service Intervals:
|
Valve adjustments, transmission service, cooling system service, fuel filter replacement typically recommended at intervals like 30,000 to 60,000 miles (48,000 to 96,000 km). Manual will detail specific interval tasks.
|
|
Fluid Specifications
|
|
Brake Fluid Type:
|
DOT 3 or DOT 4 brake fluid, depending on the specific braking system components. Manual will specify the exact Mercedes-Benz specification.
|
|
Power Steering Fluid:
|
Typically a hydraulic fluid meeting MB specifications, often CHF 11S or similar for later systems, but for W123 it might be a specific ATF or hydraulic oil. Manual is critical here.
|
|
Known Issues
|
|
Common W123 Problems:
|
Rust (especially wheel wells, rocker panels, around windows), vacuum leak issues (central locking, climate control), heater control valve failures, front suspension wear (ball joints, tie rods), thermostat housing leaks, early automatic transmission solenoids (if applicable).
|
|
Diesel Engine Specifics:
|
Glow plug issues, injection pump timing, pre-chamber wear, vacuum shut-off issues. Turbocharged models can have turbocharger wear.
|
|
Technical Specifications
|
|
Spark Plug Gap:
|
Will vary by gasoline engine (e.g., 0.8mm for M102). Manual will provide exact gap for each engine variant.
|
|
Valve Clearance Settings:
|
Cold or hot settings, specific values for intake and exhaust valves for each engine. Crucial for diesel engines. Manual is the definitive source.
|
