Engine:
Detailed diagnostics, repair, and overhaul of the M70 V12 engine
Engine Management:
Digjekt/Motronic engine control system, sensors, actuators, diagnostic codes
Transmission:
Repair and overhaul procedures for both the 4-speed automatic (e.g., 4HP-24) and manual transmissions
Drivetrain:
Rear-wheel drive system, differential, driveshafts, axle components
Suspension:
Front and rear suspension systems, components, alignment, bushings, shocks/struts
Steering:
Power steering system, steering rack, linkages, adjustments
Brakes:
Hydraulic system, ABS (Anti-lock Braking System), brake pads, rotors, calipers, lines, bleeding procedures
Electrical System:
Comprehensive wiring diagrams, component testing, battery, alternator, starter, fuses, relays
Lighting:
Headlights, taillights, interior lighting, troubleshooting
Climate Control:
Air conditioning system, heating, ventilation, blower motor, climate control module
Body And Chassis:
Body panel removal/installation, doors, hood, trunk, interior trim, glass, corrosion protection
Fuel System:
Fuel pump, injectors, fuel lines, fuel tank, EVAP system
Exhaust System:
Exhaust manifolds, catalytic converters, mufflers, pipes
Cooling System:
Radiator, water pump, thermostat, coolant hoses, fan assembly
Safety Systems:
Airbag system (if equipped), seatbelt mechanisms
Maintenance:
Regular scheduled maintenance, fluid changes, filter replacements, inspections
Troubleshooting:
Systematic diagnostic procedures for common and uncommon faults
Repair:
Step-by-step repair instructions for all major components and systems
Overhaul:
Complete engine and transmission rebuild procedures
Replacement:
Component replacement procedures (e.g., alternator, water pump, fuel injectors)
Adjustment:
Adjustment procedures for various systems (e.g., valve lash, idle speed)
Specifications:
Torque specifications, clearances, tolerances, diagnostic data
Diagnostic Capabilities:
Advanced diagnostics, including specific procedures for BMW's proprietary systems of the era
Rebuild Level:
Full engine and transmission rebuild procedures, suitable for professional mechanics and experienced DIYers
Electrical Diagrams:
Detailed, color-coded wiring diagrams for all vehicle circuits
Special Tools:
Identification and usage of specialized BMW tools required for certain repairs
Transmission Type Standard:
4-speed Automatic (e.g., ZF 4HP-24)
Transmission Type Optional:
6-speed Manual (rare, typically 1990-1992 models, Rarity Code: S671)
Automatic Features:
Electronic control, adaptive shift programs
Automatic Transmission Fluid:
BMW ATF LT3 or equivalent (e.g., Dexron III)
Automatic Transmission Fluid Capacity:
Approximately 8-10 liters (check manual for exact quantity)
Oil Change Interval:
Typically every 7,500 - 10,000 miles or annually, depending on driving conditions and oil used (check manual for specific BMW recommendations).
Spark Plug Replacement:
Long-life iridium plugs were often used, with intervals around 100,000 miles, but should be verified.
Coolant Flush:
Every 2-3 years or 30,000-40,000 miles
Engine Oil Type:
Synthetic SAE 5W-30 or 5W-40 (BMW Longlife-01 recommended, consult manual for exact specification)
Engine Oil Capacity:
Approx. 7.5 Liters (7.9 US Quarts)
Coolant Type:
BMW Blue Coolant (G48 or equivalent ethylene glycol-based coolant)
Brake Fluid Type:
DOT 4 (or DOT 4 LV for ABS systems)
Engine Vibration:
Potential for minor vibration due to V12 complexity; uneven running can indicate ignition or fuel delivery issues.
Cooling System:
Plastic components (expansion tank, thermostat housing) can degrade over time; water pump seals can fail.
Electrical Gremlins:
As with many complex electronics of this era, sensor failures, wiring harness issues, and module failures can occur.
Door Seal Wear:
Seals can perish, leading to water ingress; pop-up headlights can also develop issues.
Suspension Bushings:
Age-related wear on rubber bushings in the suspension and subframes is common.
Bmw Philosophy:
BMW's long-standing reputation for engineering excellence, driver engagement ('The Ultimate Driving Machine'), and innovative technology
Design Inspiration:
Influenced by BMW's Z1 concept and advanced aerodynamics, featuring a low drag coefficient
Engine Development:
The M70 V12 was BMW's first production V12 engine, a significant engineering feat and a statement of intent in the luxury performance segment.
Production Period:
1989-1999 (E31 platform)
Manufacturing Location:
Dingolfing, Germany
Total Units Produced:
Approximately 30,600 units across all variants (including 840i, 850Ci, 850CSi)
Variant Distinction:
The 850i was the initial V12 model, later evolving into the 850Ci with minor updates. The high-performance 850CSi (with the S70 engine) and the V8-powered 840i were also part of the E31 family.
