The 1974 Buick Century is a solid mid-size platform built on GM's A-body with durable Buick V8s, but emissions strangling and the TH350/TH400 automatics are the weak links. These cars suffer from the early smog-era complexity without the refinement, leading to carburetion headaches and transmission longevity issues under modern driving conditions.
TH350/TH400 Automatic Transmission Failures
Common · high severityTypical onset: 80,000-120,000 mi
Symptoms: Slipping between gears, especially 2nd to 3rd, Delayed engagement when shifting to Drive or Reverse, Burnt transmission fluid smell and dark red/brown fluid color, Hard shifts or banging into gear
Fix: Full rebuild required in most cases—clutch packs, bands, seals, and torque converter replacement. TH350 takes 10-14 hours labor, TH400 adds 2-3 hours. OEM-quality parts are still available but expect a week turnaround at most shops.
Estimated cost: $1,800-3,200
Carburetor and Emissions Control System Failures
Common · medium severitySymptoms: Hard starting when cold, excessive cranking time, Rough idle, stalling at stop lights, Poor fuel economy (single digits in city driving), Hesitation on acceleration, black smoke from exhaust
Fix: The Rochester Quadrajet needs frequent rebuilds—seals dry out, accelerator pump fails, choke pulls off get sticky. Factor 3-5 hours for proper rebuild with emissions system diagnosis. Many shops convert to Edelbrock but that creates inspection issues in some states. EGR valves clog and vacuum lines crack constantly.
Estimated cost: $450-900
Engine Oil Consumption from Worn Piston Rings
Common · medium severityTypical onset: 100,000-150,000 mi
Symptoms: Blue smoke on startup and during acceleration, Burning through a quart of oil every 500-800 miles, Oil fouled spark plugs, especially on #1 and #8 cylinders, Low compression readings below 120 psi on multiple cylinders
Fix: Ring replacement requires full engine disassembly—20-30 hours labor depending on 350 or 455. At this mileage, most shops recommend full rebuild including bearings, timing chain, and oil pump since you're already that deep. 455 parts cost 20-30% more than 350.
Estimated cost: $3,500-5,500
Transmission Oil Cooler Line Failures
Occasional · high severityTypical onset: any mileage
Symptoms: Transmission fluid leaking near radiator or along frame rail, Pink or red fluid mixing with coolant in overflow tank, Transmission overheating, especially towing or highway driving, Milky or strawberry-colored transmission fluid on dipstick
Fix: Steel lines rust through at mounting clips and radiator connections—common failure point on all GM A-bodies of this era. Replacement takes 2-3 hours including making proper flares and bends. If cooler contaminated coolant, both systems need flushing. Cheap fix if caught early, catastrophic if fluid mixes.
Estimated cost: $250-600
Frame Rust and Body Mount Deterioration
Common · high severitySymptoms: Visible rust perforation on rear frame rails behind rear axle, Body mounts crumbling, doors misaligning or not closing properly, Floor pan rust-through under driver's feet and rear seat, Squeaks and rattles over bumps from loose body-to-frame connection
Fix: This is geography-dependent but devastating in rust belt cars. Body mounts are 6-8 hours to replace all eight. Frame repair requires professional welding and certification if structural—expect 15-25 hours. Many cars are economically totaled by this issue. Inspect thoroughly before purchase.
Estimated cost: $800-4,000
Power Steering Pump and Gearbox Leaks
Occasional · low severityTypical onset: 70,000-110,000 mi
Symptoms: Whining noise when turning, especially when cold, Heavy steering effort at low speeds or parking, Power steering fluid dripping from pump or gearbox, Fluid reservoir constantly low despite top-offs
Fix: Saginaw pumps develop seal leaks and bearing noise—pump replacement is 2-3 hours. Gearbox sector shaft seals leak externally, requiring box removal and rebuild or replacement at 4-6 hours. Parts availability is excellent, OEM-quality rebuilds widely available.
Estimated cost: $350-800
Buy one if you're handy with carburetors and patient with 1970s quirks—mechanically simple but needs constant tuning and rust inspection is absolutely critical before purchase.
AI-assisted summary drawn from NHTSA recall data, our labor-times database, and platform knowledge. Not a substitute for a pre-purchase inspection on a specific vehicle.