The 1987 Cutlass Supreme represents the tail end of GM's rear-wheel-drive G-body platform — solid bones but showing age in drivetrain components and typical GM electrical gremlins. The Olds 307 V8 is torquey but asthmatic; the Buick 231 V6 (3.8L) is more common and generally reliable if maintained.
Timing Chain Stretch and Nylon Cam Gear Failure (307 V8)
Common · high severityTypical onset: 80,000-120,000 mi
Symptoms: Engine rattling on cold start that quiets after warm-up, Rough idle, backfiring through carburetor, Hard starting or no-start after sitting (jumped timing), Check engine light with timing-related codes
Fix: GM's nylon-toothed cam gear deteriorates and timing chains stretch excessively. Requires front cover removal, timing set replacement (metal gear upgrade essential), and often new oil pump and front seal while you're in there. Book time 6-8 hours; experienced techs can do it in 5.
Estimated cost: $800-1,400
Rochester Quadrajet Carburetor Issues
Common · medium severitySymptoms: Bog or hesitation on acceleration, Black smoke from exhaust, fuel smell, Flooding, hard hot starts, Idle surging or stalling when warm
Fix: The Q-jet is rebuildable but requires expertise — accelerator pump diaphragms fail, float needles stick, secondary air valves bind. Modern ethanol fuel accelerates deterioration. Professional rebuild takes 3-4 hours including R&R and tuning; quality rebuild kits are essential. Some shops won't touch them anymore and recommend Edelbrock or Holley swaps instead.
Estimated cost: $450-750 rebuild, $600-900 for aftermarket replacement
TH200-4R Transmission Converter Lockup and Fourth Gear Failure
Occasional · high severityTypical onset: 90,000-140,000 mi
Symptoms: Shudder or chatter at 40-50 mph cruise, No fourth gear or slipping in overdrive, Torque converter stays locked at stops causing stalling, Burnt transmission fluid smell
Fix: The TH200-4R (metric 200) overdrive was GM's weak link — lockup solenoid circuits fail, and fourth gear clutches burn out under load. Requires transmission rebuild with upgraded clutches and better converter. Plan on 10-12 hours for R&R and rebuild. Some shops won't rebuild these; they swap in beefier TH350s instead (loses overdrive).
Estimated cost: $1,800-2,800
Body Control Module and Ignition Module Heat Failures
Common · medium severitySymptoms: No-start when hot, starts fine cold, Stalling in traffic or after extended driving, Intermittent gauge cluster failures, Power windows or locks working intermittently
Fix: GM's HEI ignition modules and early body control electronics cook themselves under hood heat. Ignition module replacement is 0.5 hours (mounted on distributor); BCM diagnosis can take 2-3 hours because problems are intermittent. Heat-sink compound and proper grounding are critical on reinstall.
Estimated cost: $150-350 for ignition module, $400-800 for BCM issues
Rear Main Seal and Oil Pan Gasket Leaks
Common · low severityTypical onset: 70,000+ mi
Symptoms: Oil puddles under rear of engine, Oil coating on transmission bellhousing, Low oil level between changes, Oil drips from behind motor mounts
Fix: GM's rope-style rear main seals weep with age; two-piece oil pan gaskets leak at the timing cover junction. Rear main requires transmission removal (6-8 hours labor); oil pan can often be done in-chassis with motor mount loosening (3-4 hours). Neither is urgent unless it's a quart every 500 miles.
Estimated cost: $500-900 oil pan, $800-1,200 rear main
Upper and Lower Ball Joint Wear
Occasional · high severityTypical onset: 80,000-120,000 mi
Symptoms: Clunking over bumps in steering, Wandering, loose steering feel, Tire wear on inside or outside edges, Play in front wheels when jacked up
Fix: G-body front suspension uses serviceable ball joints that wear out. Lower joints typically fail first. Requires pressing out old joints and installing new (or replacing entire control arms with loaded assemblies). Factor 4-6 hours for both sides plus alignment. Not a DIY job without a press.
Estimated cost: $600-1,000 both sides
Buy one if you're handy or have a trusted independent shop — plan $1,500-2,500 in deferred maintenance on any example, but they're simple, parts are cheap, and the platform is unkillable if you stay ahead of the timing chain.
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.