The 1966 Buick Skylark is a solid mid-size GM A-body with robust drivetrain options, but suffers from aging rubber mounts, fuel system deterioration, and the typical catastrophic engine failures you'd expect from 60+ year-old iron that's often been neglected or improperly stored.
Transmission Mount Collapse and Drivetrain Vibration
Common · medium severitySymptoms: Clunking when shifting between drive and reverse, Excessive vibration at idle in gear, Visible sag or tearing of rubber transmission mount
Fix: Replace transmission mount and inspect engine mounts simultaneously. Original rubber compounds don't survive 60 years. Expect 1.5-2 hours labor with transmission properly supported.
Estimated cost: $150-300
Fuel System Degradation (Tank, Lines, Filter)
Common · high severitySymptoms: Hard starting or stalling after sitting, Fuel odor in cabin or garage, Rust particles in carburetor bowl, Vapor lock on hot days
Fix: Original steel fuel lines rust from inside out, tank develops sediment, and inline filter clogs repeatedly. Full system overhaul means tank removal, boil-out or replacement, new sending unit, complete steel or NiCopp line replacement, new fuel pump, and inline filter. Figure 8-12 hours for thorough job.
Estimated cost: $800-1,800
Catastrophic Engine Bearing Failure (All V8 Options)
Occasional · high severityTypical onset: 80,000-150,000 mi
Symptoms: Heavy knocking on cold start that quiets with oil pressure, Metallic tapping that worsens under load, Low oil pressure at idle when hot, Metal shavings in oil pan
Fix: Main and rod bearings fail from decades of thermal cycling, improper oil, or long storage periods. Once knocking starts, it's too late—metal-to-metal contact has scored journals. Short block replacement or complete engine rebuild required. Expect 20-30 hours for proper rebuild with machine work, or 12-16 hours for R&R with replacement engine.
Estimated cost: $3,500-7,500
Piston Ring Blow-by and Compression Loss
Occasional · medium severityTypical onset: 100,000+ mi
Symptoms: Blue smoke on deceleration or startup, Excessive oil consumption (1 quart per 500-800 miles), Poor acceleration and power loss, Wet, carbon-fouled spark plugs
Fix: Original rings lose tension, and cylinder walls glaze over from short trips and poor maintenance. Re-ring job requires heads off, ridge reaming, honing if walls are salvageable, new rings, bearings, and gaskets. If cylinder taper exceeds 0.006 inches, you're into full bore/oversize pistons. Budget 18-24 hours labor.
Estimated cost: $2,200-4,000
Automatic Transmission Oil Cooler Clogging (TH400/ST300)
Occasional · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Transmission overheating after highway driving, Burned ATF smell, Slipping or delayed engagement when hot, Dark or varnished transmission fluid
Fix: Factory cooler integrated into radiator tanks clogs with debris and varnish. External cooler lines corrode through. Flush cooler if salvageable, or replace radiator and add external auxiliary cooler. Also service transmission with new filter, gasket, and fluid. Combined 3-5 hours labor.
Estimated cost: $600-1,200
Valve Train Wear and Lifter Noise (Especially 300/340 V8s)
Occasional · low severityTypical onset: 60,000-100,000 mi
Symptoms: Ticking or tapping from valve covers at idle, Noise persists even with fresh oil change, Occasional rough idle or misfire on cold start
Fix: Hydraulic lifters pump up slowly or collapse from varnish buildup; rocker arms and pushrods develop wear grooves. Oil flush additives rarely help long-term. Proper fix is pulling valve covers, inspecting rockers/pushrods/valve tips, replacing lifters as needed. If cam lobes are worn, you're into full timing cover removal. Budget 6-10 hours for lifter replacement with proper break-in procedure.
Estimated cost: $800-1,600
Buy one if you're prepared for a project or it has documented recent drivetrain work; these are mechanically straightforward and parts are available, but decades of deferred maintenance turn them into money pits 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.