1991 MAZDA RX-7

Typical onset: 80,000-120,000 mi

Symptoms: Loss of compression on hot starts or hard starting when warm, White or blue smoke from exhaust especially on deceleration, Poor idle quality and rough running, Oil consumption over 1 quart per 1,000 miles, Failed compression test showing under 90 psi per rotor face

Fix: Complete rotary rebuild or replacement required. Apex seals wear from poor oil quality, overheating, or carbon buildup. Street port and rebuild takes 20-30 hours labor plus machine work. Many owners opt for upgraded Racing Beat or Atkins seals during rebuild.

Estimated cost: $3,500-6,500

Typical onset: 90,000-140,000 mi

Symptoms: Loud whistle or grinding noise under boost, Blue smoke on acceleration, Loss of boost pressure or slow spool, Oil puddles under turbo heat shield, Excessive shaft play in turbo cartridge

Fix: Hitachi HT-18S turbos fail from oil starvation or age. Oil feed and drain lines crack and leak. Rebuild turbo or replace with upgraded unit, replace all oil lines with braided steel. 6-10 hours labor depending on access and whether downpipe studs snap.

Estimated cost: $1,200-2,800

Typical onset: 60,000-100,000 mi

Symptoms: Temperature climbing past halfway mark under load, Coolant leaking from water pump weep hole or rear housing, Collapsed or soft radiator hoses, Steam from hood vents or overflow tank boiling, Heater blowing cold while engine overheats

Fix: Original radiators corrode internally, water pumps fail, and coolant seals in the housings leak. Overheating kills apex seals instantly. Full cooling refresh: radiator, hoses, water pump, thermostat, and coolant seal replacement takes 8-12 hours. Critical preventive maintenance.

Estimated cost: $1,500-2,500

Typical onset: 70,000-110,000 mi

Symptoms: ATF leaking from steel lines near radiator, Transmission slipping or delayed engagement when hot, Pink or milky transmission fluid indicating coolant contamination, Puddles of red fluid under front of car

Fix: Steel transmission cooler lines rust through at bends or fittings. On automatics, internal radiator cooler can fail and mix ATF with coolant, destroying both systems. Replace lines with NiCopp or stainless, flush transmission and cooling system. 3-5 hours labor.

Estimated cost: $400-800

Typical onset: 80,000-130,000 mi

Symptoms: Clunking on throttle application or lift, Excessive vibration at idle, Shifter movement or grinding during shifts, Visible separation or cracking in rubber mount insulators

Fix: All rubber mounts deteriorate with age and heat exposure. Front engine mount and both transmission mounts commonly fail. Replace all three as a set for proper alignment. 2-3 hours labor with proper jacking and support.

Estimated cost: $300-600

Symptoms: Erratic idle or stalling, Poor boost control or overboost, Check engine light with lean codes, Wastegate actuator not responding, Rat's nest of cracked vacuum lines under manifold

Fix: The rats nest of vacuum lines, solenoids, and actuators under the intake manifold crack and leak with age. Systematic replacement of all vacuum lines, check valves, and solenoids recommended. Upgrade to silicone lines. 4-6 hours to do properly.

Estimated cost: $400-900

Typical onset: 80,000-120,000 mi

Symptoms: Fuel starvation under hard acceleration or cornering, Hesitation or stumbling under boost, Difficulty starting after sitting, Fuel smell in cabin or from tank area, Visible rust or debris in fuel filter

Fix: Fuel filter clogs from tank rust, fuel lines crack, and injectors gum up. Pre-turbo fuel starvation is dangerous. Replace main and pre-filters, inspect and replace cracked rubber lines, clean or replace injectors. Fuel pump may need replacement. 3-5 hours.

Estimated cost: $500-1,200