The W124 E500 is a hand-built limited-production muscle sedan powered by the M119 5.0L V8—a robust but aging aluminum engine that demands meticulous maintenance. When neglected, this platform becomes a money pit; when cared for, it's one of the most durable luxury sedans ever made.
M119 Engine Wiring Harness Degradation
Common · high severityTypical onset: 80,000-150,000 mi
Symptoms: Hard starting or no-start conditions, Rough idle and misfires, Check engine light with multiple cylinder misfire codes, Fuel smell in engine bay from cracked injector seals
Fix: Complete engine harness replacement requires 12-16 hours labor. Biodegradable insulation fails, exposing wires to heat and oil. Must replace entire harness—patch jobs fail within months. Injector seals should be done simultaneously.
Estimated cost: $2,800-4,200
Head Gasket Failure and Block Porosity
Occasional · high severityTypical onset: 120,000-180,000 mi
Symptoms: Coolant loss with no visible leaks, White smoke from exhaust on cold starts, Overheating under load, Milky oil or coolant in expansion tank
Fix: Head gasket job requires 18-22 hours. Early M119 blocks (pre-'93) have porosity issues causing coolant seepage into cylinders. Some cases need block replacement or sleeving. Always pressure-test block before reassembly.
Estimated cost: $4,500-7,500
Transmission Oil Cooler Line Failure
Common · medium severityTypical onset: 100,000-160,000 mi
Symptoms: Transmission fluid pooling under vehicle, Fluid dripping near radiator area, Slipping or delayed shifts after fluid loss, Burnt fluid smell
Fix: Steel lines rust through at mounting points. Replacement takes 3-4 hours including fluid flush. Must replace both cooler lines and inspect radiator-mounted cooler for cross-contamination. Always change transmission filter during this repair.
Estimated cost: $800-1,400
Transmission Mount and Flex Disc Deterioration
Common · medium severityTypical onset: 80,000-140,000 mi
Symptoms: Clunk when shifting from park to drive, Vibration at idle that smooths out under load, Visible cracks in rubber flex disc, Driveline shudder during acceleration
Fix: Transmission mount typically fails first (3 hours labor), but flex disc should be inspected simultaneously. If flex disc is cracked, it's another 2-3 hours. Failure to address flex disc can cause driveshaft separation—a dangerous condition.
Estimated cost: $600-1,200
Self-Leveling Rear Suspension (SLS) Sphere and Accumulator Failure
Occasional · low severityTypical onset: 90,000-150,000 mi
Symptoms: Rear end sags overnight or after sitting, Hydraulic pump runs excessively, Uneven ride height side-to-side, Groaning noise from rear suspension
Fix: Accumulators lose nitrogen charge over time; spheres develop leaks. Each corner takes 2-3 hours. Many owners delete SLS entirely and convert to coil springs (6-8 hours), which eliminates future issues but loses load-leveling capability.
Estimated cost: $1,200-2,000 (repair) or $1,800-2,800 (coil conversion)
Valve Cover and Oil Pan Gasket Leaks
Common · low severityTypical onset: 70,000-120,000 mi
Symptoms: Oil pooling under vehicle after sitting, Burning oil smell from exhaust manifolds, Oil coating visible on valve covers, Low oil level between changes
Fix: Valve covers are 6-7 hours due to coil pack removal and harness routing. Oil pan requires subframe drop on E500 (8-10 hours). These are maintenance items but expensive due to labor intensity on the M119. Do them together if both are leaking.
Estimated cost: $1,400-2,600
Engine Wiring Harness Thermal Damage Near Manifolds
Occasional · medium severitySymptoms: Intermittent crank sensor codes, Random stalling when hot, Tach needle bouncing or dropping to zero, No-start after heat-soak
Fix: Even after full harness replacement, wiring routed too close to exhaust manifolds can fail again. Requires heat shielding and rerouting (2-4 hours). Heat-damaged wires are brittle and break internally—diagnosis can be time-consuming.
Estimated cost: $400-900
Buy only if maintenance records are immaculate and budget exists for wiring harness and inevitable gasket work—a well-maintained E500 is glorious, but a neglected one 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.