The E24 633CSi with the M30 3.2L inline-six is a solid, over-engineered grand tourer, but age is the enemy—expect degraded fuel system components, transmission cooling issues, and worn engine internals if deferred maintenance is evident. Most survivors are 35+ years old, so condition trumps mileage.
Automatic Transmission Overheating & Cooler Line Failures
Common · high severityTypical onset: 100,000+ mi or age-related
Symptoms: Transmission slipping or harsh shifts when hot, ATF leaking from corroded cooler lines at radiator, Burnt ATF smell, dark brown fluid, Loss of drive after highway runs
Fix: Replace transmission oil cooler lines (often rusted through), flush and refill ATF, inspect cooler itself. If internal damage occurred from overheating, expect a rebuild: 12-18 hours labor for R&R and overhaul.
Estimated cost: $800-1,500 for lines and fluid; $3,500-5,500 for full rebuild with torque converter
Fuel System Degradation (Hoses, Filter, Injectors)
Common · medium severityTypical onset: All surviving examples due to age
Symptoms: Hard starting when hot or after sitting, Rough idle, hesitation under load, Fuel smell in engine bay or cabin, Check engine light (if applicable—early OBD systems)
Fix: Replace all rubber fuel hoses (they harden and crack after 30+ years), fuel filter, and often fuel injectors or full cleaning. Expect 4-6 hours for comprehensive fuel system refresh.
Estimated cost: $600-1,200 depending on injector condition
M30 Engine Worn Piston Rings & Valve Guides
Occasional · high severityTypical onset: 150,000-250,000 mi
Symptoms: Blue smoke on startup or deceleration, Excessive oil consumption (1+ quart per 1,000 mi), Low compression on multiple cylinders, Fouled spark plugs
Fix: Requires engine-out rebuild: new rings, hone cylinders, valve seals/guides, timing components, gaskets. Count on 30-40 hours total including R&R and machine work. Some opt for low-mileage used engine swap instead.
Estimated cost: $5,000-8,500 for rebuild; $3,500-5,000 for used engine swap
Crankshaft Position Sensor & Ignition System Failures
Occasional · high severityTypical onset: Any mileage—heat and age related
Symptoms: No-start or sudden stalling while driving, Intermittent crank-no-start when engine is hot, Tachometer drops to zero while running, Car dies and restarts after cooling
Fix: Replace crank position sensor (common failure point), distributor cap/rotor, ignition coil, plug wires. Sensor replacement is 1-2 hours; full ignition refresh is 3-4 hours.
Estimated cost: $300-700 depending on scope
Transmission and Engine Mounts Collapsed
Common · medium severityTypical onset: 80,000+ mi or original mounts
Symptoms: Clunking on acceleration or deceleration, Excessive engine movement visible from bay, Vibration at idle transmitted into cabin, Shifter slop or hard engagement
Fix: Replace all motor and transmission mounts—rubber deteriorates and tears. Typical job is 3-5 hours depending on access and exhaust removal needs.
Estimated cost: $500-900 parts and labor
Head Gasket Failure & Coolant System Leaks
Occasional · high severityTypical onset: 120,000+ mi or overheating history
Symptoms: White smoke from exhaust, sweet smell, Coolant loss with no visible external leak, Overheating under load or in traffic, Oil contamination with coolant (milky dipstick)
Fix: Head gasket replacement requires removing cylinder head, resurfacing, new gasket set, timing components, coolant flush. 12-16 hours labor. Often uncover additional issues (cracked head, warped deck).
Estimated cost: $2,200-3,800 if head is reusable; more if cracked
Electrical Gremlins (Relay Board, Window/Sunroof Motors)
Common · low severityTypical onset: Age-related, any mileage
Symptoms: Intermittent no-start, no-crank (check relay board), Power windows slow or inoperative, Sunroof motor stalls or grinds, Gauges flickering or inaccurate
Fix: Inspect and resolder main relay board (under hood, common cold solder joints). Window regulators and motors fail—each door is 2-3 hours. Sunroof motor/track rebuild is 4-6 hours.
Estimated cost: $200-500 for relay board; $400-700 per window regulator/motor; $600-1,000 for sunroof overhaul
Buy one only if you love the E24 chassis and have a $3,000-5,000 buffer for sorting—these are projects, not daily drivers, but rewarding if you wrench yourself.
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.