1994 MAZDA RX-7

Typical onset: 60,000-100,000 mi

Symptoms: Hard starting when warm, excessive cranking, Loss of power, poor acceleration, White or blue smoke on deceleration, Rough idle, misfiring at low RPM, Failed compression test (below 6.5 kg/cm² per rotor face)

Fix: Full engine rebuild required—housings resurface or replacement, new apex/corner/side seals, bearings, gaskets. Plan 25-35 labor hours for removal, teardown, machining, rebuild, reinstall. DIY-friendly if you have space and patience, but most send it out. Core condition affects parts cost heavily.

Estimated cost: $4,000-8,000

Typical onset: 70,000-120,000 mi

Symptoms: No boost or flat power delivery above 4,500 RPM, Check engine light with turbo control codes, Loud hissing or boost leaks under load, Secondary turbo not spooling (stuck precontrol valve), Erratic boost spikes or wastegate rattle

Fix: Diagnose vacuum routing first—30-year-old rubber lines crack and collapse. Replace all vacuum hoses, rat's nest delete common upgrade (3-4 hours). Solenoid pack or precontrol actuator replacement adds 2-3 hours each. Turbo rebuild/replacement if bearings failed: 8-12 hours per side.

Estimated cost: $800-3,500

Typical onset: 50,000-90,000 mi

Symptoms: Overheating in traffic or on track, Coolant loss with no visible leaks (warped AST), Steam from engine bay after shutdown, Coolant in oil or vice versa (failed O-rings in coolant jacket), Heater blowing cold despite thermostat opening

Fix: These engines generate immense heat—OEM two-row radiator is marginal. Upgrade to Koyo aluminum 3-row (4 hours). Air Separator Tank (AST) warps, leaks internally—replace proactively (2 hours). Water pump impeller delaminates by 80k—replace with timing belt service (included in 6-8 hour job). Coolant jacket O-ring failure requires engine-out rebuild.

Estimated cost: $1,200-2,800

Typical onset: 60,000-100,000 mi

Symptoms: Loud clunk on throttle lift or engagement, Vibration at highway speeds (driveline angle changed), Difficulty shifting into gear, grinding, Excessive driveline movement visible when rocking car in gear

Fix: Front transmission mount (PPF brace) and rear diff bushings deteriorate, allowing powertrain to shift under load. Replace all mounts as a set—front requires subframe work (3-4 hours), rear diff bushings add 2 hours. Upgraded urethane mounts last longer but increase NVH.

Estimated cost: $600-1,200

Typical onset: 80,000-120,000 mi

Symptoms: Stalling or stumbling when hot, restarts after cooling, Fuel pump whine audible in cabin, Hard starting, long crank times, Lean condition codes, hesitation under boost, Fuel pressure dropping below 38-40 PSI

Fix: Twin fuel pumps in tank feed sequential turbos—either can fail. Pump replacement requires tank drop (4-5 hours for both). Heat soak from turbos/exhaust causes vapor lock in feed lines—insulate lines, upgrade to Walbro 255 pumps ($450 parts). Recall addressed some hose routing but check fire-prone hard lines near turbo.

Estimated cost: $800-1,400

Symptoms: Check engine light with multiple vacuum leak codes, Rough idle, high idle hang after revving, Poor fuel economy, rich running, Rats nest of cracked hoses under intake manifold

Fix: The infamous 'rats nest' of vacuum lines, solenoids, and emissions equipment under the UIM becomes brittle. Full delete/simplification takes 6-8 hours, requires blocking ports, rerouting essentials. Most owners do this preventively with aftermarket kits. Keeps everything else working longer.

Estimated cost: $400-900

Typical onset: 70,000-110,000 mi

Symptoms: Whining or growling from PS pump, heavy steering, Battery light flickering, electrical gremlins, Squealing belt on startup (bearing failure), Fluid leaking from PS pump seals

Fix: Accessories mounted low near turbos cook in heat soak. PS pump seals leak, bearings fail—replacement 2-3 hours. Alternator brushes wear or diodes fail—remanufactured unit 2 hours. Both fail earlier with track use or Southern climates. Upgrade to higher-output alternator if adding audio.

Estimated cost: $500-1,100