The 1968 LeMans is a solid A-body platform with robust drivetrains, but suffers from typical 1960s GM body rust, aging rubber mounts, and carburetor tuning issues. Engine longevity is good if maintained, but neglected examples often need major lower-end work.
Transmission and Engine Mounts Deterioration
Common · medium severityTypical onset: 50,000+ mi or 20+ years regardless of miles
Symptoms: Excessive drivetrain clunk on acceleration/deceleration, Visible engine movement at idle, Vibration through floor and shifter, Transmission tailshaft sitting low
Fix: Replace all mounts (typically 3-4 depending on configuration). Transmission mount is most critical and fails first. 2-3 hours labor for full mount replacement.
Estimated cost: $300-600
Lower End Bearing Failure (Mains and Rods)
Occasional · high severityTypical onset: 80,000-150,000 mi on original engine, or sooner with oil neglect
Symptoms: Deep knocking at idle that worsens under load, Loss of oil pressure especially when hot, Metallic debris in oil filter, Sudden catastrophic failure if ignored
Fix: Requires engine removal, full teardown, crank inspection/machining, new bearings, and reassembly. Often triggers complete rebuild once you're in there. 25-35 hours labor for proper R&R and rebuild.
Estimated cost: $3,500-6,500
Carburetor Issues (Rochester 2-barrel or Quadrajet)
Common · low severitySymptoms: Hard starting when cold or hot, Rough idle and stumbling on acceleration, Fuel leaking from gaskets or accelerator pump, Black smoke indicating rich running
Fix: Usually needs full rebuild with kit or replacement. Quadrajets are finicky and often improperly adjusted. 3-5 hours for removal, rebuild, reinstall, and tuning.
Estimated cost: $400-800
Floor Pan and Trunk Rust-Through
Common · high severitySymptoms: Visible rust holes in floor under carpet/mat, Trunk floor soft or perforated, Rocker panels crumbling, Frame rail surface rust or scaling
Fix: Rust repair ranges from patch panels to full floor replacement. Trunk floors and rear frame rails are notorious rot areas. 15-40 hours depending on extent, requires welding skills.
Estimated cost: $2,000-8,000
Fuel System Contamination and Line Deterioration
Occasional · medium severitySymptoms: Repeated fuel filter clogging, Fuel starvation under load, Fuel smell in cabin or trunk, Hard starting after sitting
Fix: Old rubber fuel lines crack and break down internally, sending debris downstream. Gas tank often full of rust and sediment. Replace all lines, filters, tank cleaning or replacement. 6-10 hours.
Estimated cost: $600-1,500
Rear Axle Seal Leaks
Common · low severityTypical onset: 60,000+ mi or age-related
Symptoms: Gear oil dripping from rear wheel area, Oil coating inside of rear brake drums, Reduced rear differential fluid level
Fix: Replace axle seals and possibly axle bearings if worn. Rear brakes will need cleaning or replacement if contaminated. 3-4 hours per side.
Estimated cost: $400-700
Ignition System Degradation (Points and Condenser)
Common · medium severitySymptoms: Misfiring and hesitation, Hard starting, Stalling at idle, Loss of power at highway speed
Fix: Points-type ignition requires regular maintenance. Points wear, condensers fail, distributor advance mechanisms stick. Many owners upgrade to electronic ignition. 2-3 hours for tune-up or electronic conversion.
Estimated cost: $200-600
Buy one if the body is solid and the engine doesn't knock—mechanical parts are available and straightforward, but rust repair will bankrupt you.
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.