1990 BMW 740IL E32

Typical onset: 60,000-120,000 mi

Symptoms: Excessive oil consumption (1+ quart per 500 miles), Loss of compression in multiple cylinders, Cold-start misfires that worsen over time, Visible cylinder wall scoring on borescope inspection, Rough idle and power loss

Fix: The Nikasil-coated aluminum bores were sensitive to high-sulfur fuel common in early 1990s. Only real fix is engine replacement or complete rebuild with Alusil block or sleeved cylinders. Engine-out job requires 25-35 hours labor plus machine work. Many owners source later Alusil blocks (1995+ M60) or swap to M62 from E38. Short-block replacement alone runs 18-22 hours.

Estimated cost: $6,500-12,000

Typical onset: 80,000-150,000 mi

Symptoms: Red ATF pooling under vehicle, Transmission overheating warnings, Harsh or delayed shifts when hot, Oil cooler lines weeping at crimp connections, Milky transmission fluid if cooler ruptures internally

Fix: The transmission oil cooler lines run along the driver's side frame rail and corrode from road salt and age. Cooler itself can crack internally, mixing ATF with coolant. Replace both supply and return lines preventatively, plus the auxiliary cooler if leaking. External cooler replacement is 3-4 hours; lines add another 2-3 hours if corroded fasteners fight you. Flush transmission after any coolant contamination.

Estimated cost: $800-1,800

Typical onset: 70,000-120,000 mi

Symptoms: Clunk when shifting from Park to Drive, Vibration at 45-55 mph that feels transmission-related, Visible transmission sag or excessive movement, Grinding sensation during acceleration, Exhaust heat shield rattles from driveline movement

Fix: The rubber transmission mount at the rear of the bellhousing collapses, allowing the transmission to drop and throwing driveline angles off. This accelerates flex disc wear at the differential. Replace transmission mount (2-3 hours with proper support) and inspect guibo flex disc at same time. Both fail together frequently on high-mileage examples.

Estimated cost: $400-900

Typical onset: 100,000+ mi

Symptoms: Hard starting when hot, Stumble or hesitation under acceleration, Stalling at idle after warm-up, Fuel smell in trunk area, Whining fuel pump audible in cabin

Fix: Fuel filter lives under the car near the tank and rarely gets changed per 30k-mile schedule. Clogged filter starves the engine. In-tank fuel pump fails from running dry or contaminated fuel. Rubber fuel lines in engine bay crack and leak. Filter replacement is 0.5 hours; pump replacement requires tank drop (4-5 hours). Replace all rubber fuel hoses in engine bay preventatively—they're 30+ years old.

Estimated cost: $350-1,200

Typical onset: 80,000-140,000 mi

Symptoms: Battery warning light flickering or steady, Dimming headlights at idle, Electrical accessories acting erratically, Battery repeatedly dying, Voltage gauge reading below 12V at idle

Fix: Bosch alternators fail from brush wear and diode bridge corrosion. Voltage regulator can fail separately. Alternator replacement on M60 is straightforward (2-3 hours) but requires removing cooling fan shroud for access. Use OEM Bosch or Valeo units—cheap rebuilds fail within months. Check battery cables and main ground straps at same time; corrosion causes false charging symptoms.

Estimated cost: $500-900

Typical onset: Any mileage

Symptoms: Rear end sagging after sitting overnight, Compressor running constantly, Uneven rear ride height side-to-side, Warning light for suspension malfunction, Hydraulic fluid leaks at accumulator or lines

Fix: The Electronic Height Control (EHC) system uses hydraulic accumulators and a pump to level the rear. Accumulators lose pressure over time, pump seals leak, and ride-height sensors corrode. Many owners delete the system and install coil-spring conversion kits (6-8 hours labor). Rebuilding OEM system costs more but maintains correct ride. Accumulator spheres alone are $400-600 per pair, pump rebuild another $500+.

Estimated cost: $1,200-2,800