Segment:
Full-size luxury sedan.
Positioning:
Flagship model, representing BMW's pinnacle of engineering, comfort, and performance during its era.
Key Competitors:
Mercedes-Benz S-Class (W126/W140), Lexus LS 400, Jaguar XJ6, Audi V8 Quattro.
Luxury Appointments:
Premium interior materials, advanced comfort features, refined ride quality, substantial sound insulation.
Performance Focus:
Engaging driving dynamics characteristic of BMW, powerful inline-six and V12 engines.
Technological Advancements:
Early adoption of ABS, traction control (ASC), advanced engine management systems, and electronic climate control.
Engine Mechanical:
Engine overhaul, timing systems, valve train, cylinder heads, block assembly, pistons, crankshaft, lubrication systems, cooling systems.
Engine Management:
Fuel injection systems (Motronic), ignition systems, emission control systems, sensor diagnostics, ECU operation.
Transmission:
Automatic transmission overhaul (e.g., ZF 4HP22, 4HP24), manual transmission (if applicable for specific variants), clutch system, driveline, driveshafts, differentials.
Suspension:
Front and rear suspension components, shock absorbers, springs, control arms, bushings, wheel alignment specifications, self-leveling suspension (if equipped).
Brakes:
Front and rear brake systems (disc brakes), ABS (Anti-lock Braking System) diagnostics and repair, brake fluid specifications, caliper and rotor replacement.
Electrical:
Wiring diagrams for all vehicle systems, lighting, starter, alternator, battery, fuse boxes, relays, power windows, power locks, central locking, mirrors, sunroof, instrument cluster.
Body:
Body panel repair, door mechanisms, trunk lid, hood, bumpers, interior trim removal and installation, weather stripping.
HVAC:
Climate control system diagnostics and repair, refrigerant handling, blower motor, heater core, A/C compressor, evaporator.
Interior:
Seating systems, dashboard removal, steering wheel and column, audio systems, diagnostic connectors.
Maintenance:
Oil changes, filter replacements, spark plug replacement, coolant flushes, brake fluid changes, lubrication points, belt inspections and replacement.
Troubleshooting:
Diagnostic procedures for common and uncommon issues, fault codes interpretation, symptom-based troubleshooting guides.
Repair:
Detailed step-by-step instructions for component replacement, overhaul procedures, adjustments, and calibration.
Diagnostics:
Procedures for using diagnostic tools, interpreting sensor data, and pinpointing electrical and mechanical faults.
Depth Level:
Comprehensive, covering basic maintenance to complete engine and transmission rebuilds, complex electrical diagnostics.
Specialized Procedures:
ABS bleeding procedures, idle speed control adjustments, catalytic converter testing, EPROM replacement (if applicable), self-leveling suspension service.
Length 735I 740I:
Approx. 196.4 inches (4988 mm)
Length 735Il 740Il 750Il:
Approx. 203.5 inches (5169 mm)
Wheelbase 735I 740I:
Approx. 117.4 inches (2982 mm)
Wheelbase 735Il 740Il 750Il:
Approx. 124.5 inches (3162 mm)
Curb Weight 735I:
Approx. 3750 lbs (1701 kg)
Curb Weight 740I:
Approx. 3850 lbs (1746 kg)
Curb Weight 750Il:
Approx. 4300 lbs (1950 kg)
NHTSA Ratings:
Not extensively tested by modern standards; structural integrity generally considered high for its era.
ABS:
Standard on most models, Bosch ABS II.
Traction Control:
Optional/Standard on later models (ASC - Automatic Stability Control).
Airbags:
Driver-side airbag standard from approx. 1990/1991 onwards. Passenger airbag optional or standard on later models.
Seatbelts:
Three-point inertia-reel seatbelts front and rear.
Body Structure:
Reinforced chassis and safety cell for crash protection.
Audio System:
Premium sound systems (e.g., Blaupunkt, Harman Kardon) with cassette player, radio, optional CD changer.
Display Technology:
Analog gauges, central information display for trip computer and system warnings.
Cruise Control:
Standard electronic cruise control.
Parking Assistance:
Rear park distance control (optional on some models).
Phone Integration:
Optional factory-installed car phone systems (early mobile technology).
Climate Control:
Dual-zone automatic climate control.
Seats:
Power-adjustable front seats with memory, heated seats (optional).
Lighting:
Power-adjustable headlights, fog lights.
Remote Locking:
Central locking system, optional remote keyless entry on later models.
Windows Mirrors:
Power windows, power mirrors, power sunroof.
Oil Change Interval Miles:
Typically 5,000 - 7,500 miles or annually, depending on driving conditions.
Coolant Flush Interval Miles:
Every 2 years or 30,000 miles.
Spark Plug Replacement Miles:
M30: 30,000 miles; M60/M70: 60,000 miles (may vary).
Brake Fluid Change Interval Years:
Every 2 years.
Engine Oil Spec 735I:
API SG, SAE 5W-30 or 10W-40 (check manual for exact specification).
Engine Oil Spec 740I 750Il:
API SG, SAE 5W-30 or 10W-40 (check manual for exact specification).
Coolant Spec:
BMW Blue Antifreeze/Coolant (G48), mixed 50/50 with distilled water.
Transmission Fluid Auto:
Dexron II or III (check manual for exact specification).
Common Problems M30:
Head gasket leaks, oil pan gasket leaks, oil pan baffle failure, timing chain guides wear, coolant leaks (hose failures, water pump), fuel distributor issues on early models.
Common Problems M60:
Nikasil cylinder bore degradation (in earlier M60B30/B40 engines, less common in later ones), VANOS unit issues, eccentric shaft sensor failure, oil leaks (valve cover gaskets, oil pan gaskets).
Common Problems M70:
Ignition coil issues (one per cylinder), throttle body actuator problems (two per engine), complex fuel and ignition management, cooling system complexity, harmonic balancer failure.
Electrical Issues:
Corrosion in wiring harnesses, failure of door lock actuators, sunroof motor issues, climate control unit failures, ABS sensor failures.
Complexity:
These vehicles are complex and require specialized knowledge and tools for proper maintenance and repair.
