1973 BMW 2002

Typical onset: 120,000-180,000 mi

Symptoms: Knocking or rod knock on cold start that lessens when warm, Low oil pressure at idle (under 10 psi hot), Excessive blowby or smoking from oil filler cap, High oil consumption (quart per 500-800 miles)

Fix: Full engine rebuild or short block replacement. Main and rod bearings shot from age and oil neglect. Expect 25-35 hours labor for complete teardown, machine work (deck, bore, crank grind), reassembly with new rings, bearings, gaskets, timing components, oil pump. Many opt for full rebuild while it's apart.

Estimated cost: $4,500-8,000

Symptoms: Excessive drivetrain clunk on engagement or deceleration, Shifter vibration at idle, Visible engine movement when blipping throttle, Transmission tunnel heat and noise

Fix: Rubber mounts disintegrate after decades regardless of mileage. Transmission mount is the worst offender and causes huge clunking. Engine mounts allow excessive movement. Replace all three mounts as a set (two engine, one trans). 2-3 hours labor with basic hand tools.

Estimated cost: $350-650

Symptoms: Hard starting or no-start after sitting, Stumbling, hesitation, or flat spots during acceleration, Flooding or fuel leaks from carb base, Rough idle or stalling when cold

Fix: Solex or Weber carbs gum up from ethanol fuel and sitting. Requires full disassembly, cleaning, new gaskets, float valve, accelerator pump diaphragm. Fuel filter often neglected and clogs. Add new fuel lines if original rubber. 3-5 hours for carb rebuild plus fuel system service.

Estimated cost: $450-900

Typical onset: 100,000-150,000 mi

Symptoms: Valve clatter or ticking that worsens when cold, Loss of power and poor fuel economy, Hard starting, Uneven idle

Fix: M10 requires valve adjustment every 3,000-6,000 miles but most haven't seen it in decades. Worn cam lobes, rocker arms, and valve seats common. If caught early, adjustment and cam inspection is 2 hours. If worn, head removal for valve job, cam replacement, new rockers adds 12-18 hours.

Estimated cost: $150-300 (adjustment) / $2,000-3,500 (head work)

Typical onset: 80,000-140,000 mi

Symptoms: Grinding into second gear, especially when cold, Difficulty downshifting into second, Jumping out of second gear under load, Notchy or balky shifts

Fix: Getrag 232 four-speed notorious for second gear synchro failure. Requires transmission removal, disassembly, synchro ring replacement, new bearings while apart. 8-12 hours labor. Many upgrade to five-speed conversion instead of rebuilding worn four-speed.

Estimated cost: $1,800-3,200

Symptoms: Oil drips on garage floor after sitting, Oil residue coating engine bay and undercarriage, Burning oil smell from valve cover leaks onto exhaust, Rear main seal leak into bellhousing

Fix: 50-year-old cork and rubber gaskets leak everywhere: valve cover, oil pan, front and rear main seals, oil filter housing. Not urgent but messy. Valve cover is 1 hour, oil pan 3-4 hours, rear main seal requires transmission removal (8+ hours). Most do them piecemeal unless doing engine-out rebuild.

Estimated cost: $200-500 (valve cover and pan) / $800-1,200 (rear main)