Positioning:
The BMW 525i (E34) was a prominent luxury executive sedan, offering a blend of performance, comfort, and sophisticated engineering. This manual serves owners and technicians looking to maintain and repair this classic BMW.
Competitors:
Competed with vehicles such as the Mercedes-Benz E-Class (W124), Audi 100/200, and Jaguar XJ6 of the same era.
Vehicle Features:
Renowned for its refined ride, capable handling, durable M50 engine, and iconic BMW styling.
Value Proposition:
Provides essential information for DIY enthusiasts and professional mechanics to accurately diagnose, maintain, and repair the 1991 BMW 525i, ensuring longevity and optimal performance.
Engine:
M50B25 engine diagnostics, repair, overhaul, timing, fuel injection (Bosch Motronic 3.1), ignition system, lubrication system, cooling system, emissions control
Transmission:
Manual and Automatic transmission removal, installation, overhaul, clutch system, gear shift linkage, automatic transmission control module
Drivetrain:
Rear-wheel drive system, driveshaft, universal joints, differential, axle shafts, wheel bearings
Suspension:
Front and rear suspension systems, struts, shock absorbers, control arms, bushings, springs, anti-roll bars, steering linkage
Brakes:
Front and rear disc brakes, ABS (Anti-lock Braking System) diagnostics and repair, brake fluid specifications, caliper and rotor replacement, parking brake system
Electrical:
12-volt electrical system, battery, alternator, starter, fuses, relays, lighting system, horn, power windows, power seats, central locking, diagnostic connectors, wiring diagrams
Bodywork:
Body panel removal and installation, doors, hood, trunk lid, bumpers, glass replacement, seals, corrosion protection, interior trim
Heating Ventilation Air Conditioning:
HVAC system operation, troubleshooting, component replacement (compressor, condenser, evaporator, blower motor), refrigerant system servicing
Fuel System:
Fuel tank, fuel pump, fuel filter, fuel lines, fuel injectors, fuel pressure regulator
Maintenance:
Scheduled maintenance, oil changes, filter replacements, tune-ups, fluid checks and changes
Troubleshooting:
Diagnostic procedures for common faults, symptom-based troubleshooting guides, fault codes interpretation
Repair:
Detailed step-by-step repair instructions for all major systems and components
Overhaul:
Complete engine and transmission overhaul procedures
Diagnostics:
On-board diagnostics (OBD-I) procedures, sensor testing, ECU diagnostics
Depth:
Comprehensive, from basic maintenance to full engine and transmission rebuilds, advanced electrical diagnostics
Engine Type:
Inline 6-cylinder, DOHC, 24 valves
Displacement:
2.5 liters (2494 cc)
Horsepower:
189 hp @ 5,900 rpm (approx.)
Torque:
245 Nm (181 lb-ft) @ 4,700 rpm (approx.)
Fuel Delivery:
Bosch Motronic 3.1 Fuel Injection
Fuel Type:
Unleaded Gasoline (Premium Octane Recommended)
Coolant Capacity:
Approx. 8.5 liters (8.9 quarts)
Oil Capacity:
Approx. 6.5 liters (6.9 quarts) with filter change
Recommended Oil Viscosity:
SAE 5W-30 or 5W-40 (Synthetic recommended)
Type:
5-speed Manual Transmission (Getrag 260/5)
Type:
4-speed Automatic Transmission (ZF 4HP22)
Automatic Features:
Sport mode for more aggressive shifting
Automatic Transmission Fluid:
BMW ATF Dexron II or equivalent
Manual Transmission Fluid:
BMW MTF LT-1 or equivalent (GL-4 rated)
Oil Change Interval:
Every 7,500 to 10,000 miles (12,000 to 16,000 km) or annually, depending on driving conditions (refer to manual for exact BMW recommendations).
Spark Plug Replacement:
Approximately every 30,000 miles (48,000 km) for standard plugs; longer for platinum/iridium.
Coolant Flush:
Every 2-3 years or 30,000-50,000 miles (48,000-80,000 km).
Power Steering Fluid:
BMW CHF 11S or equivalent Pentosin
Common Problems:
Head gasket leaks (especially on early M50s), cooling system component failure (water pump, thermostat, expansion tank), VANOS unit (if equipped later in the run or swapped), oil pan gasket leaks, fuel injector O-ring leaks, ABS sensor failures, worn suspension bushings, O2 sensor failure.
Preventative Maintenance:
Regular inspection of cooling system hoses and components, timely replacement of belts and fluids, checking for oil leaks.
