1994 MAZDA COSMO

Typical onset: 60,000-100,000 mi

Symptoms: Hard cold starts requiring extended cranking, Loss of power, poor acceleration, Excessive oil consumption (more than 1 qt per 1,000 mi), White or blue smoke from exhaust on startup

Fix: Rotary engines wear apex seals that ride against the rotor housing. Unlike piston rings, these are failure-prone when owners skip premix or run lean. Rebuild involves complete disassembly, housing resurfacing, new seals/springs/gaskets, and reassembly with careful clearance checks. Expect 20-30 labor hours for a shop rebuild, more for the 20B triple-rotor due to complexity.

Estimated cost: $4,500-8,000

Typical onset: 80,000-120,000 mi

Symptoms: Harsh or delayed shifts, especially 2-3 upshift, Slipping under load or in higher gears, Transmission overheating, burnt ATF smell, Check engine light with trans-related codes

Fix: The 4-speed auto (shared with some RX-7s) suffers from worn clutch packs and weak oil cooler design. Transmission removal, teardown, clutch/band replacement, valve body refurbishment, and reinstallation. Also replace the transmission oil cooler and lines while out. 12-16 hours labor.

Estimated cost: $2,800-4,500

Typical onset: 70,000-110,000 mi

Symptoms: Temperature gauge climbing into red zone, Coolant leaks from hoses, water pump, or radiator, Steam from engine bay, Repeated loss of coolant with no visible leak (failed eccentric shaft seals)

Fix: Rotaries generate tremendous heat and the Cosmo's cooling system ages poorly—original hoses crack, radiators clog, water pumps leak. If coolant enters the rotor housings via failed internal seals, it hydrolock or score housings, forcing a rebuild. Replace radiator, hoses, water pump, and thermostat as preventive maintenance. 6-8 hours if caught early; if housings are damaged, see apex seal rebuild above.

Estimated cost: $1,200-2,000

Typical onset: all ages

Symptoms: Rough idle, stumbling on throttle tip-in, Check engine light with lean codes, Poor fuel economy, Boost control issues on turbocharged 13B-RE

Fix: The Cosmo has dozens of vacuum lines (emissions, boost control, secondary air injection). Rubber degrades after 30 years, causing leaks. Methodical diagnosis with smoke machine and vacuum gauge. Replace all suspect hoses, secure fittings, and check solenoids. 3-5 hours of diagnostic and repair time.

Estimated cost: $400-800

Typical onset: not mileage-specific

Symptoms: Long cranking before start, especially when hot, Hesitation or stumble under acceleration, Fuel smell in cabin or near tank, Engine stalling after warmup

Fix: Fuel pumps (in-tank on some models), filters, and injectors age poorly. The 20B triple-rotor uses six primary and six secondary injectors—any failing injector causes lean conditions that kill apex seals. Replace fuel filter, pump if noisy, and clean or replace injectors. 4-6 hours depending on access.

Estimated cost: $600-1,400

Typical onset: 80,000-130,000 mi

Symptoms: Loss of boost pressure, Blue smoke on acceleration, Whining or grinding noise from turbo, Oil leaking from turbo into intake or exhaust

Fix: The sequential twin-turbo system on the 13B-RE is complex and prone to bearing wear if oil changes are skipped. Turbo removal, rebuild or replacement, gaskets, and vacuum line inspection. 8-12 hours labor.

Estimated cost: $1,800-3,200