The 1968 Buick Skylark is a solid A-body platform hampered by typical GM automatic transmission fragility and age-related engine wear. Most survivors need bottom-end work or complete rebuilds due to decades of deferred maintenance rather than inherent design flaws.
TH350/TH400 Automatic Transmission Failure
Common · high severityTypical onset: 80,000-120,000 mi
Symptoms: Harsh or delayed 1-2 shift, Slipping in third gear under load, Burnt transmission fluid smell, No reverse or erratic engagement
Fix: Complete rebuild with new clutches, bands, seals, and torque converter. External cooler lines often corroded and leak. Budget 12-16 labor hours for R&R and rebuild.
Estimated cost: $1,800-3,200
Worn Piston Rings and Cylinder Ridge Wear
Common · medium severityTypical onset: 100,000+ mi
Symptoms: Blue smoke on startup and deceleration, High oil consumption (quart per 500-800 miles), Low compression across multiple cylinders, Blowby visible at oil filler cap
Fix: Requires engine removal, bore inspection, honing or overbore, new pistons and rings. Most shops recommend full rebuild at this point since heads come off anyway. 20-30 hours depending on seized fasteners and rust.
Estimated cost: $3,500-6,000
Crankshaft Main Bearing Failure
Occasional · high severitySymptoms: Heavy knocking from bottom end, worsens with RPM, Metal shavings in oil pan, Sudden loss of oil pressure, Visible crankshaft endplay movement
Fix: Complete teardown to inspect crank journals for scoring. Often needs machine work or replacement crank plus align bore. Combined with inevitable other worn components, turns into full rebuild. 25-35 hours.
Estimated cost: $4,000-7,500
Rusted and Collapsed Fuel Lines
Common · medium severitySymptoms: Fuel smell in cabin or under vehicle, Hard starting after sitting, Engine starvation under acceleration, Visible corrosion or wet spots along frame rails
Fix: Replace steel fuel lines from tank to pump and pump to carb. Often need custom bending or pre-fab kit. 4-6 hours if no complications; doubles if lines are seized to clips or frame rust is severe.
Estimated cost: $400-900
Transmission Mount Deterioration
Common · low severitySymptoms: Clunk when shifting from Park to Drive/Reverse, Excessive driveline vibration at idle in gear, Visible rubber separation or cracking on mount, Transmission tail housing sitting too low
Fix: Replace rubber transmission mount and inspect crossmember for cracks. Straightforward job, 1-2 hours. Often done alongside transmission service.
Estimated cost: $150-300
Leaking Transmission Oil Cooler Lines
Occasional · medium severitySymptoms: ATF puddles under front of vehicle, Low transmission fluid level with no visible pan leak, Crispy or corroded steel lines at radiator connections, Transmission overheating in traffic
Fix: Replace both pressure and return cooler lines. Often corroded at radiator fittings and frame clips. 2-3 hours if lines come out clean; add time for seized fittings.
Estimated cost: $250-500
Buy only if the engine and transmission have verifiable recent rebuilds or you budget $5,000-8,000 for both within the first year.
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.