1956 BUICK CENTURY

Symptoms: Transmission fluid pooling under car, especially after sitting, Excessive drivetrain clunk when shifting into Drive or Reverse, Vibration at idle that worsens under load

Fix: Dynaflow units leak from pan gaskets, rear seals, and cooler lines due to age-hardened seals. Transmission mount rubber deteriorates after 60+ years causing excessive movement. Reseal job: 6-8 hours. Mount replacement: 2 hours. Often done together.

Estimated cost: $800-1,500

Typical onset: 80,000-120,000 mi

Symptoms: Deep knocking sound from bottom end, worst on cold start, Low oil pressure at idle (under 10 psi when warm), Metallic debris in oil filter or pan

Fix: The 322 Nailhead suffers bearing wear if oil changes were neglected or if run with non-detergent oils originally specified. Requires engine removal, full teardown, crank inspection/possible turning, new bearings, and reassembly. Budget 30-40 hours for complete in-frame overhaul or 25-30 for short block replacement.

Estimated cost: $3,500-6,500

Symptoms: Raw fuel smell, black smoke from exhaust, Engine flooding after sitting, hard to start when hot, Flat spot or stumble during acceleration, Fuel dripping from carb throat or air cleaner

Fix: Original Carter WCFB 4-barrels have aged needle/seat assemblies, warped floats, and deteriorated accelerator pump diaphragms. Full rebuild kit plus careful float adjustment: 4-6 hours including removal, bench work, and tuning.

Estimated cost: $400-750

Typical onset: 90,000-140,000 mi

Symptoms: Blue smoke on startup and deceleration, Consuming 1+ quart per 500 miles, Low compression readings (under 100 psi), Excessive crankcase pressure, oil leaking from valve covers

Fix: Ring wear is common on high-mileage or poorly-maintained Nailheads. Requires cylinder honing, new rings on all pistons, often new valve seals simultaneously. Can be done in-frame if cylinders aren't scored: 20-25 hours. If cylinders need boring, full rebuild required.

Estimated cost: $2,200-4,000

Symptoms: Engine dies in hot weather or after extended idling, Rough running, surging, or stalling after highway drives, Difficulty restarting when heat-soaked, Fuel starvation symptoms under load

Fix: Factory fuel line routing near exhaust manifolds causes vapor lock. Original inline filters rust internally or clog with varnish from old fuel. Replace filter (1 hour), reroute fuel lines away from heat with insulation (3-4 hours), consider electric fuel pump upgrade.

Estimated cost: $300-800

Typical onset: 120,000+ mi

Symptoms: Heavy knocking that doesn't respond to bearing replacement, Metallic grinding noise from deep in engine, Oil pressure drops to zero at idle, Crank throws visibly scored during inspection

Fix: Severe neglect or bearing failure can score crank journals beyond standard undersize limits. Requires crank removal, machine shop work (grinding undersize or welding/regrinding), or replacement crank. Engine-out job: 35-45 hours total with machine work turnaround.

Estimated cost: $4,500-7,500