The 1967 Buick GS is a first-year muscle car with solid Nailhead or new 400ci V8s, but decades of age mean worn powertrains, deteriorated transmission coolers, and failed engine seals are the norm on survivors—budget for major mechanical work if buying.
Automatic Transmission Failure (TH400/ST400)
Common · high severityTypical onset: 80,000-120,000 mi or unknown history
Symptoms: Slipping between gears, especially 1-2 shift, Delayed engagement into Drive or Reverse, Burnt transmission fluid smell or dark/gritty fluid, Cooler line leaks at radiator or external cooler
Fix: Full rebuild with clutch packs, bands, seals, and filter; external cooler lines and radiator cooler tank often corroded and need replacement. Expect 12-16 hours labor plus parts.
Estimated cost: $2,200-3,800
Head Gasket Failure (Both Banks)
Common · high severityTypical onset: 60,000-100,000 mi or after overheating
Symptoms: Coolant loss with no visible external leaks, White smoke from exhaust on startup, Milky oil on dipstick or oil cap, Overheating or rough idle
Fix: Pull both heads, resurface if warped, replace gaskets and often intake manifold gaskets simultaneously; deck surface condition critical on 50+ year old blocks. 18-24 hours labor.
Estimated cost: $1,800-3,200
Lower End Bearing Wear (Mains and Rods)
Occasional · high severityTypical onset: 100,000+ mi or unknown maintenance history
Symptoms: Deep knocking from bottom of engine, worse under load, Low oil pressure at idle when hot (under 10 psi), Metallic debris in oil filter or pan, Gradual loss of power
Fix: Full engine teardown, crank removal and inspection, main and rod bearing replacement; often requires crank machining or replacement if journals scored. 30-40 hours labor for full rebuild.
Estimated cost: $4,500-7,500
Piston Ring Blowby and Cylinder Wear
Common · medium severityTypical onset: 80,000+ mi, accelerated by poor maintenance
Symptoms: Blue smoke on deceleration or at startup, Excessive oil consumption (quart per 500-800 miles), Low compression across multiple cylinders, Fouled spark plugs
Fix: Engine removal, complete disassembly, cylinder honing or boring oversized, new pistons and rings, bearing inspection. 35-45 hours for full rebuild.
Estimated cost: $4,000-6,500
Transmission Oil Cooler Line Corrosion
Common · medium severitySymptoms: Transmission fluid dripping from radiator area or underneath, Fluid level dropping quickly after topping off, Pink/red fluid mixing with coolant if internal cooler fails
Fix: Replace both steel cooler lines from transmission to radiator; flush cooling system if internal contamination occurred. 2-4 hours labor depending on routing and fittings.
Estimated cost: $300-600
Crankshaft Seal and Rear Main Leak
Occasional · medium severityTypical onset: 70,000+ mi or age-related deterioration
Symptoms: Oil pooling under bellhousing area, Oil spots on driveway after sitting overnight, Clutch or flexplate contamination, Gradual oil level drop
Fix: Transmission removal required, replace rear main seal and often front timing cover seal simultaneously; inspect for crank wear. 8-12 hours labor.
Estimated cost: $800-1,400
Buy for the style and rarity, but only if you have deep pockets or DIY skills—nearly every survivor needs major engine or transmission work due to age alone.
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.