BMW 8 Series E31 Factory Workshop Manual
Factory repair manual for the BMW 8 Series E31 (1990–1999). A comprehensive technical guide to servicing and restoring this legendary grand tourer. An indispensable resource for working with V8 engines (M60, M62) and flagship V12 engines (M70, M73). The manual includes detailed repair procedures for:
- The comprehensive electronic engine management (DME) system.
- Complete tightening torques for all chassis components and high-performance engines.
- The unique Integral Rear Axle (AHK) steering system.
- Step-by-step instructions for diagnosing and repairing automatic and manual transmissions.
- Pop-up headlights and complex on-board electronics.
- Wiring diagrams for troubleshooting power supply and comfort controls.
Full E31 Workshop Manual
BMW 8 Series E31: Popular Problems
The BMW 8 Series (E31) is a complex, exclusive grand tourer that was the pinnacle of BMW engineering in its era. Due to its complexity and age (the "youngest" models are over 25 years old), it has a number of characteristic and costly issues.
Automatic Transmission (4HP24/5HP30): Older automatic transmissions require frequent fluid and filter changes but often fail due to clutch pack wear and issues with electronics/solenoids, especially at high mileage or after aggressive driving.
Electrical and Electronic Systems (The E31's Core Challenge)
| Problem | Cause and Symptoms |
| Wiring Harness Degradation (WOT) | The wiring harnesses, especially in the engine bay and under the rear seats, degrade over time. The insulation crumbles, leading to short circuits. |
| ECU Failures (DME) | V12 models (850i, 850Ci) use two DMEs (one for each cylinder bank), doubling the failure probability. |
| Instrument Cluster/ICM Issues | Degradation of electronic components (capacitors) within the control units and the instrument panel. |
Engine Problems (M70/M73 V12 and M60/M62 V8)
| Problem | Cause and Symptoms |
| V12 Service Accessibility | The V12 engine bay is extremely cramped, making even simple services like spark plug replacement, gasket replacement, or thermostat changes extremely labor-intensive. |
| Oil Leaks | Over time, the gaskets for the oil pan, valve covers, and especially the oil pump tube O-rings on the V8/V12 harden and begin to leak. |
| Cooling System | The radiator, thermostats (especially the dual thermostats on the V12), and plastic components wear out over time, which is critical given the engine displacement and heat output. |
Chassis and Bodywork
| Problem | Cause and Symptoms |
| Front Suspension Wear | Rapid wear of ball joints, control arm bushings, and tie rod ends due to the car's weight and power. |
| Pop-up Headlights | The electric motor mechanism driving the headlights wears out or malfunctions due to wiring/relay issues. |
| Doors and Windows | Wear in the window regulator mechanisms and door adjustment systems, common on frameless coupe windows. |