The 1973 Firebird represents the last of the second-gen platform before emissions strangling really began. These cars are mechanically robust but suffer from age-related issues with 50-year-old components, particularly in the drivetrain and fuel delivery systems.
TH350/TH400 Automatic Transmission Failure
Common · high severityTypical onset: 80,000-140,000 mi
Symptoms: Slipping between gears, especially 1-2 shift, Delayed engagement when shifting to Drive or Reverse, Burnt transmission fluid smell, dark or metallic fluid, Hard or erratic shifting patterns
Fix: Complete rebuild with hard parts inspection, usually requires torque converter replacement. Expect 12-16 labor hours for removal, rebuild, and reinstall. At this age, most units need clutch packs, seals, bushings, and valve body work.
Estimated cost: $2,200-3,800
Worn Main and Rod Bearings (V8 engines)
Common · high severityTypical onset: 100,000-150,000 mi
Symptoms: Deep knocking sound from lower engine, worse under load, Low oil pressure at idle, especially when warm, Metallic debris in oil filter or on drain plug magnet, Engine roughness that increases with RPM
Fix: Short block overhaul or replacement required. Pull engine, inspect crank journals for scoring, replace bearings, often needs crank grinding. If crank damage is severe, full rebuild or crate engine. 25-35 hours for engine R&R plus machine work wait time.
Estimated cost: $3,500-6,500
Carburetor Issues (Rochester 2GC/Quadrajet)
Common · medium severitySymptoms: Hard starting when cold or hot, Rough idle, stalling at stop signs, Black smoke from exhaust, fuel smell, Poor fuel economy, hesitation on acceleration
Fix: Rebuild kit installation including all gaskets, accelerator pump, needle/seat, and float adjustment. Ethanol fuel deteriorates original components. Most techs spend 3-5 hours on a proper Quadrajet rebuild with choke adjustment and tuning.
Estimated cost: $450-850
Piston Ring Blowby and Cylinder Wear
Occasional · high severityTypical onset: 120,000-180,000 mi
Symptoms: Excessive blue smoke on startup and deceleration, High oil consumption (1 quart per 500-800 miles), Loss of compression, poor power output, Positive crankcase pressure, oil leaks from valley cover
Fix: Full engine rebuild with bore and hone, new pistons and rings, valve job. If cylinders measure over 0.005" taper, needs boring to next oversize. 30-40 hours including teardown, machine work coordination, and reassembly.
Estimated cost: $4,500-7,500
Fuel System Varnish and Line Deterioration
Common · medium severitySymptoms: Fuel starvation at highway speeds, Fuel smell in cabin or garage, Hard starting after sitting, runs fine after warmup, Visible fuel weeping from metal lines at frame rail
Fix: Replace rubber fuel hoses, metal lines if rusted through, fuel filter, and clean tank. Many cars need fuel pump replacement due to ethanol damage. Tank removal and cleaning adds significant labor. 4-8 hours depending on line condition.
Estimated cost: $600-1,400
Transmission Mount and Crossmember Failure
Occasional · medium severityTypical onset: 60,000-100,000 mi
Symptoms: Clunking when shifting into gear, Excessive driveline vibration at acceleration, Visible sagging of transmission tail housing, Shifter movement feels loose or notchy
Fix: Replace rubber transmission mount and inspect crossmember for cracks. Often both mount and crossmember need replacement due to rust perforation. Simple job at 1.5-2.5 hours if no rust complications.
Estimated cost: $250-500
Valvetrain Wear (455 V8 Specific)
Occasional · medium severityTypical onset: 80,000-120,000 mi
Symptoms: Valve train clatter that doesn't quiet with warmup, Loss of power in upper RPM range, Metal shavings in valve covers during oil change, Rocker arm stud pull-out on high-mileage engines
Fix: Heads-off valve job with new guides, seals, springs. 455 engines are prone to rocker stud issues requiring thread inserts or screw-in studs. Expect 18-24 hours for both heads with proper machine work.
Estimated cost: $2,800-4,200
Buy one if you're prepared for eventual major drivetrain work and have access to a competent mechanic who knows carburetors — when maintained, these are reliable cruisers, but deferred maintenance gets expensive fast.
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.