1968 BMW 2002

Typical onset: 100,000-150,000+ mi or unknown history

Symptoms: Deep knocking at idle that worsens with RPM, Low oil pressure at operating temp, Metallic debris in oil filter, Rod knock on cold start that may or may not disappear when warm

Fix: Engine-out rebuild with new main bearings, rod bearings, and often associated crank polishing or replacement. Budget 20-30 hours for complete teardown, machine work coordination, and reassembly. High-mileage or poorly-maintained examples often need full shortblock work when you're in there.

Estimated cost: $3,500-6,500

Typical onset: 120,000+ mi

Symptoms: Excessive blue smoke on deceleration or startup, High oil consumption (1 qt per 500-800 miles), Loss of compression and power, Wet, carbon-fouled spark plugs

Fix: Requires engine removal, bore honing or overbore, new piston rings or complete piston set. Often combined with bearing replacement since you're already there. 25-35 hours total including head work if needed. Many shops recommend a complete rebuild at this point rather than piecemeal work.

Estimated cost: $4,000-7,000

Typical onset: 80,000-120,000 mi

Symptoms: Grinding into second gear especially when cold, Difficult downshifts into second, Gear pop-out under load in second, Crunching even with full clutch engagement

Fix: Full transmission rebuild with synchro replacement, bearings, and seals. Gearbox removal is straightforward on these cars. 12-16 hours for R&R and rebuild, more if you're replacing the clutch simultaneously (which you should).

Estimated cost: $1,800-3,200

Symptoms: Excessive drivetrain clunk on throttle tip-in, Vibration through shifter and floor at idle, Difficulty getting into gear, Visible engine movement when blipping throttle

Fix: Replace all three mounts (two engine, one transmission). Rubber degrades significantly after decades regardless of mileage. Simple job, 2-3 hours with basic tools. Do this before chasing other driveline noises.

Estimated cost: $300-600

Symptoms: Hard starting when hot, Stumbling under acceleration, Fuel smell in cabin or engine bay, Stalling after sitting, Visible fuel weeping at rubber line connections

Fix: Replace all rubber fuel lines, inline filter, and often the mechanical fuel pump diaphragm. Original rubber turns to glass after 50+ years. 3-5 hours to do it properly, including tank-to-engine hard line inspection. Critical safety item.

Estimated cost: $400-800

Typical onset: 150,000+ mi or severe neglect

Symptoms: Severe knocking that changes pitch with load, Excessive crankshaft end play (check with pry bar), Oil pressure drops to zero at idle, Metal shavings in oil pan

Fix: Requires crankshaft removal, inspection, possible regrinding or replacement, and thrust bearing replacement. 25-30 hours as part of complete engine rebuild. Often discovered during bearing replacement when journals measure out of spec.

Estimated cost: $4,500-7,500