The E34 M5 is a hand-built high-performance sedan with the legendary S38 inline-six, but age and complexity mean serious maintenance costs. These are now 30+ year-old cars where deferred maintenance becomes catastrophic quickly.
S38 Timing Chain and Guides Failure
Common · high severityTypical onset: 80,000-150,000 mi
Symptoms: rattling noise on cold start that quiets after warmup, metallic chain slap from front of engine, check engine light with cam/crank correlation codes, catastrophic engine failure if chain jumps or breaks
Fix: Complete timing chain kit including guides, tensioners, and rails. Requires front engine disassembly. 16-20 labor hours. Many shops do valve adjustment and reseal front cover while in there. This is mandatory preventive maintenance on any unknown-history S38.
Estimated cost: $3,500-5,500
Rod Bearing Failure
Occasional · high severityTypical onset: 100,000-180,000 mi
Symptoms: knocking sound from bottom end that increases with RPM, metallic ticking that doesn't go away when warm, sudden loss of oil pressure, metal shavings in oil filter or drain pan
Fix: Rod bearings wear due to age and oil change intervals. Requires engine removal or major disassembly. Most shops recommend full engine-out rebuild at this point including mains, seals, and gaskets. 35-45 hours for proper rebuild. Some owners do preventive replacement every 60-80k miles.
Estimated cost: $8,000-15,000
Transmission Output Shaft Bearing Failure (Getrag 280)
Common · medium severityTypical onset: 90,000-140,000 mi
Symptoms: whining or grinding noise that changes with vehicle speed not engine RPM, noise present in neutral with clutch out, gets louder during deceleration, can lead to total transmission failure if ignored
Fix: Output shaft bearing wears and creates noise, eventually grenading the transmission. Requires transmission removal and internal rebuild. 12-16 hours. Cannot be ignored once symptoms start. Often combined with clutch replacement while trans is out.
Estimated cost: $2,500-4,000
Cooling System Failures
Common · high severityTypical onset: any mileage over 10 years old
Symptoms: plastic radiator neck cracking, expansion tank splitting, water pump weeping or seizing, overheating under load, coolant loss with no visible leak
Fix: All plastic cooling components become brittle with age regardless of mileage. Radiator, expansion tank, hoses, and water pump should be replaced as a package on any 25+ year old car. S38 overheating can warp the head quickly. 6-8 hours for complete refresh including thermostat and all hoses.
Estimated cost: $1,500-2,500
Camshaft Wear and Valve Train Issues
Occasional · high severityTypical onset: 120,000+ mi
Symptoms: ticking or tapping from valve cover that doesn't quiet down, loss of power especially top-end, rough idle, oil consumption, metal particles in oil
Fix: S38 uses individual throttle bodies and aggressive cam profiles. Improper valve adjustments or low oil pressure cause cam lobe wear. Requires head removal, possible resurfacing, new cam(s), lifters, and complete valve job. 25-35 hours. Often discovered during timing chain service.
Estimated cost: $6,000-10,000
Fuel System and Injector Issues
Occasional · medium severityTypical onset: any age
Symptoms: hard starting when hot, rough idle or stumbling, poor fuel economy, fuel smell in cabin, check engine light with mixture codes
Fix: Fuel lines, filter, pump, and injectors all age poorly. Rubber fuel lines under car crack and leak. Injectors clog or leak. Fuel filter often neglected (should be every 30k). Complete fuel system refresh including filter, all rubber lines, and injector service/replacement. 8-12 hours depending on scope.
Estimated cost: $1,200-3,000
Transmission and Differential Mounts
Common · low severityTypical onset: 70,000-120,000 mi
Symptoms: clunking when shifting or engaging clutch, excessive driveline vibration, feeling shifts harshly, visible sagging or torn rubber in mounts
Fix: Rubber mounts deteriorate and cause driveline slop. Transmission mount and rear differential mounts are common culprits. Relatively straightforward replacement. 3-5 hours for both. Should be part of any used purchase inspection.
Estimated cost: $600-1,200
Buy only if you have a $10k cushion for deferred maintenance and access to a trusted S38 specialist — these are incredible drivers but will bankrupt the unprepared.
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.