The E24 630CSi with its M30 3.0L inline-six is fundamentally solid mechanically but suffers from age-related issues tied to 45+ year-old rubber, cooling systems, and carburetion complexity. Most survivors need comprehensive sorting of deferred maintenance rather than catastrophic repairs.
M30 Engine Head Gasket and Cylinder Head Cracks
Occasional · high severityTypical onset: 100,000-150,000 mi
Symptoms: Coolant loss with no external leaks, White smoke from exhaust, Overheating under load, Coolant in oil or oil in coolant
Fix: Head removal, pressure testing, possible crack repair or replacement, surface milling, new head gasket and bolts. Expect 12-16 hours labor. Early M30 heads (pre-1978) are prone to cracking between valve seats if overheated even once.
Estimated cost: $2,800-4,500
Zenith Carburetor Flooding and Tuning Nightmares
Common · medium severitySymptoms: Hard starting when warm, Fuel smell in cabin or garage, Rough idle and hesitation, Black smoke under acceleration, Gas puddling in intake manifold
Fix: Rebuild both carbs with quality kits, clean jets, replace float valves and accelerator pump diaphragms, sync and tune. Needs someone experienced with Zeniths. Figure 6-8 hours for proper rebuild and tuning. Many shops won't touch them—Weber conversion is common escape route.
Estimated cost: $800-1,400
Transmission Output Shaft Seal and Rear Main Seal Leaks
Common · low severityTypical onset: 80,000+ mi
Symptoms: Oil spots under bellhousing area, Transmission fluid drips from tail housing, Clutch slip from oil contamination, Low fluid levels in transmission
Fix: Output shaft seal is 3-4 hours with transmission in place. Rear main seal requires transmission removal—budget 8-10 hours labor. Both typically done together if transmission is already out. These rope seals weren't great when new.
Estimated cost: $600-1,800
Front Control Arm Bushings and Ball Joints
Common · medium severityTypical onset: 70,000-120,000 mi
Symptoms: Clunking over bumps, Wandering steering feel, Excessive tire wear on inside edges, Steering wheel vibration, Car darts on grooved pavement
Fix: Control arm bushings deteriorate into mush by now. Ball joints wear oval. Replace all four control arms with bushings pressed in, both ball joints, alignment. Pressed bushings require special tools or sublet. 6-8 hours total with alignment.
Estimated cost: $1,200-2,000
Fuel System Rust and Clogging
Occasional · medium severitySymptoms: Intermittent stalling, Inability to restart until cooled, Sputtering under load, Fuel starvation at sustained highway speed, Rust flakes in fuel filter
Fix: Tank rusts from inside out if car sat or ran ethanol fuel for years. Requires tank removal, cleaning or replacement, new fuel lines from tank forward, pump, filter, injector cleaning or carb rebuild. 8-12 hours depending on how far you go. Original steel lines often internally corroded.
Estimated cost: $1,000-2,500
Cooling System Comprehensive Failures
Common · high severitySymptoms: Overheating in traffic, Coolant leaks from multiple points, Heater ineffective, Radiator neck cracks, Expansion tank brittle and weeping
Fix: Forty-five year old cooling system needs everything: radiator, hoses, expansion tank, thermostat, water pump, fan clutch. Piecemeal repairs waste money—do it all at once. 6-8 hours labor for comprehensive refresh. Overheating once can crack the head (see above).
Estimated cost: $1,500-2,200
Electrical Gremlins from Corroded Grounds and Fuse Box
Common · low severitySymptoms: Gauges reading erratically, Intermittent no-start, Lights dimming, Turn signals working sometimes, Accessories cutting out
Fix: Ground straps corrode through, fuse box contacts oxidize, bullet connectors lose tension. Methodical ground refurbishment, fuse box cleaning/replacement, dielectric grease on connections. 4-6 hours diagnostic time often needed to chase multiple issues.
Estimated cost: $400-900
Buy one if you're handy or have a specialist nearby—these are rewarding classics with bulletproof drivetrains once sorted, but they demand proactive maintenance and aren't for those expecting modern reliability.
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.