The NA Miata is bulletproof by '90s standards, but age—not mileage—is the enemy. You're looking at a 30-year-old car where rubber, seals, and coolant routing cause most grief. The 1.8L (BP) is slightly more desirable and robust than the early 1.6L (B6).
Crankshaft Nose / Front Main Seal Oil Leak
Common · medium severityTypical onset: 80,000-150,000 mi or 20+ years regardless of miles
Symptoms: Oil puddle under timing cover area, Oil spray on underside of hood when driving, Oil consumption without visible external leak at valve cover
Fix: Front main seal and crank pulley woodruff key. Timing belt, water pump, and all front seals done at same time is smart. 4-6 hours labor.
Estimated cost: $600-1,200
Camshaft Wear (1.6L B6-ZE Specific)
Occasional · high severityTypical onset: 100,000+ mi, especially if oil changes were neglected
Symptoms: Ticking/tapping that worsens with RPM, Loss of power above 4,000 RPM, Check engine light with cam position codes, Metallic debris in oil
Fix: Cam lobes and lifters wear prematurely on early 1.6L engines due to soft cam material. Requires cylinder head removal, cam replacement, lifter replacement, head resurfacing recommended. 12-16 hours labor.
Estimated cost: $2,500-4,000
Short Nose Crankshaft Failure (Early 1.6L)
Rare · high severityTypical onset: Not mileage-driven—design flaw in 1990-1991 models
Symptoms: Catastrophic timing belt failure, Sudden loss of timing, Engine won't crank or cranks with no compression, Woodruff key sheared at crank pulley
Fix: Early 1.6L engines (1990-1991) had short-nose cranks that shear keyways. Requires long-nose crank swap or full engine replacement. 20+ hours labor if rebuilding in-car.
Estimated cost: $3,500-6,000
Coolant Crossover Pipe / Heater Hose Rot
Common · medium severitySymptoms: Coolant smell in cabin, Wet passenger-side carpet, Overheating with no visible external leak, Low coolant with no puddles under car
Fix: Steel crossover pipe under intake manifold rusts through. Requires upper intake manifold removal to access. Heater core hoses also fail. 3-5 hours labor.
Estimated cost: $400-800
Valve Cover Gasket / CAS O-Ring Leak
Common · low severityTypical onset: 60,000+ mi or 15+ years
Symptoms: Oil seepage on driver-side head, Burning oil smell, Oil on spark plug tubes, Cam angle sensor (CAS) O-ring weeps onto distributor
Fix: Valve cover gasket, spark plug tube seals, and CAS O-ring. Easy DIY. 1.5-2.5 hours labor.
Estimated cost: $200-400
Transmission Mount Collapse
Common · low severityTypical onset: 80,000-120,000 mi or rubber aged out
Symptoms: Clunk when shifting into reverse, Excessive shifter vibration at idle, Gear whine that changes with clutch engagement, Shifter moves side-to-side excessively
Fix: Powertrain Performance Mount (PPF) and transmission mount bushings wear out. Replace both while you're under there. 2-3 hours labor.
Estimated cost: $300-600
Soft Top Frame Fatigue / Window Regulator Failure
Occasional · low severitySymptoms: Top won't latch or seal properly, Bows cracked at rivets, Manual windows fall into door or crank spins freely, Driver window more common than passenger
Fix: Soft top frames crack at stress points; full frame replacement or weld repair. Window regulators strip plastic gears. Each issue 2-4 hours labor.
Estimated cost: $400-900 top frame, $250-500 per window regulator
Absolutely buy one—these are the most reliable fun cars of the '90s, but factor $1,500-3,000 for deferred maintenance on any 30-year-old example and walk away from rust.
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.