1982 BMW 320I

Typical onset: 100,000-150,000 mi

Symptoms: loud ticking or clattering from valve cover especially when cold, noise persists after valve adjustment, loss of power at higher RPM, metal shavings in oil

Fix: The M10 hydraulic lifters wear and cam lobes flatten over time, especially if oil changes were skipped. Requires cylinder head removal, camshaft replacement, full lifter set, and thorough cleaning. Plan 12-16 hours labor plus machine shop time if head needs resurfacing.

Estimated cost: $1,800-3,200

Typical onset: any mileage on original mounts

Symptoms: excessive engine movement during acceleration and deceleration, clunking when shifting or engaging clutch, vibration through shifter and cabin, drivetrain feels loose

Fix: Four-decade-old rubber mounts are almost always shot. Trans mount, two engine mounts, and sometimes the steering rack mounts all need replacement. Straightforward job, 3-4 hours total with basic hand tools.

Estimated cost: $400-700

Symptoms: hard starting when hot, stumbling or stalling in warm weather, rough idle and hesitation, fuel smell in cabin or engine bay, visible fuel weeping at injector seals

Fix: The K-Jetronic mechanical fuel injection has ancient rubber lines, deteriorating injector seals, and the fuel pump may be weak. At minimum replace all fuel hoses, filter, injector seals, and test fuel pressure. If pump is original, replace it preemptively. 4-6 hours labor.

Estimated cost: $500-1,200

Typical onset: 120,000-180,000 mi

Symptoms: rattling from front of engine on startup, timing chain noise that disappears after oil pressure builds, rough running or misfires if severely worn, engine won't start if chain has jumped

Fix: M10 timing chains stretch and guides wear. If caught early, chain, guides, tensioner, and upper rail replacement takes 6-8 hours. If chain jumps timing, expect bent valves and full head work adding another 10+ hours.

Estimated cost: $800-1,400 preventive, $2,500-4,000 if valves bent

Symptoms: overheating in traffic or highway driving, coolant leaks from radiator end tanks or hoses, heater not working properly, steam from engine bay

Fix: Original radiators have plastic end tanks that crack, water pump impellers corrode, and every rubber hose is brittle. Do the whole system at once: radiator, water pump, thermostat, all hoses, expansion tank. M10 heads crack if overheated even once. 5-7 hours labor.

Estimated cost: $700-1,400

Symptoms: clunking from rear suspension over bumps, visible rust around shock towers from inside trunk, shock towers pushed up into trunk floor, uneven tire wear

Fix: E21s rust at rear shock towers, especially cars from snow states. Minor surface rust can be wire-wheeled and sealed, but structural rust requires cutting out metal and welding in repair panels. Not a DIY job unless you have welding skills. 8-15 hours depending on damage severity.

Estimated cost: $800-2,500

Symptoms: intermittent gauge failures, lights or turn signals not working, fuses blowing randomly, no-start conditions that resolve randomly

Fix: 40-year-old wiring insulation cracks and grounds develop throughout the harness, especially in engine bay. Requires methodical troubleshooting with multimeter and often repairing or replacing individual circuits. Budget 2-6 hours depending on specific issue.

Estimated cost: $150-600