Mazda · Known Issues
1991 Mazda RX-7 Problems: 7 Known Issues
1991 model year · 280+ owner reports · Updated September 2026
1991 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
1991 model year · 280+ owner reports · Updated September 2026
1991 · All trims · All engines
Choose the year and equipment for your written issues and visual request.
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According to Au7o's analysis of 280+ owner reports, the 1991 Mazda RX-7 has 7 documented known issues, with 3 rated critical. The most serious are Overheating and Coolant System Weakness ($300-$800 repair), Turbo II Wastegate Flapper Undersizing — Boost Creep and Overboost ($300-$1,200 repair) and Oil Metering Pump Neglect and Brittle Injection Lines — Apex Seal Starvation ($200-$900 repair). The most commonly reported issue is Overheating and Coolant System Weakness with 280 owner reports. Across all issues with published estimates, repair costs range from $50 to $1,200. DIY maintenance guides at au7o.io.
LATCHES/LOCKS/LINKAGES:HOOD:LATCH
EQUIPMENT DESCRIPTION: MAZDA SPEED RESINOUS HOODS, DESIGNED AND SOLD AS ACCESSORY PARTS FOR MODEL YEAR 1992-1995 RX7 VEHICLES, MANUFACTURED BETWEEN JUNE 1, 1997, THROUGH SEPTEMBER 19, 2000.
ENGINE AND ENGINE COOLING:COOLING SYSTEM
THE RADIATOR CAP PRESSURE RELIEF VALVE RELEASE PRESSURE IS SET TOO HIGH. THIS CAN CAUSE THE COOLANT TO REACH TEMPERATURES THAT EXCEED THE THERMAL DESIGN LIMITS OF SOME COMPONENTS OF THE COOLANT SYSTEM. SHOULD THIS OCCUR, ENGINE COOLANT CAN LEAK COLLECT ON TOP OF THE ENGINE.
FUEL SYSTEM, GASOLINE:DELIVERY:HOSES, LINES/PIPING, AND FITTINGS
RESIDUAL ENGINE HEAT CAN CAUSE PREMATURE DETERIORATION OF THE FUEL HOSE CAUSING THE HOSE TO LEAK. ALSO, REMOVING AND REINSTALLING THE DETERIORATED FUEL HOSES INCREASES THE LIKELIHOOD OF A LEAK.
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According to Au7o's analysis of 280+ owner reports, the 1991 Mazda RX-7 has 7 documented issues. The most frequently reported are: Overheating and Coolant System Weakness, Turbo II Wastegate Flapper Undersizing — Boost Creep and Overboost, Oil Metering Pump Neglect and Brittle Injection Lines — Apex Seal Starvation. Of these, 3 are rated critical and should be addressed promptly.
The 1991 Mazda RX-7 has 7 known issues documented across 280+ owner reports. 3 issues are rated critical: Overheating and Coolant System Weakness and Turbo II Wastegate Flapper Undersizing — Boost Creep and Overboost and Oil Metering Pump Neglect and Brittle Injection Lines — Apex Seal Starvation. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.
Repair costs for known Mazda RX-7 issues range from $50 to $1,200, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Overheating and Coolant System Weakness, typically costs $300-$800 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.
Rotary engines generate extreme heat and the cooling system is barely adequate, especially on turbo models. Radiator, thermostat, and water pump failures cause rapid overheating that quickly damages apex seals. Repairs typically run $300-$800. Severity: high.
The Hitachi HT-18 turbocharger on the FC Turbo II uses an internal wastegate port of only about 16 mm — roughly half the size used by comparable turbos — and the small flapper door cannot bypass enough exhaust at high RPM. The result is boost creep (boost continuing to climb past… Repairs typically run $300-$1,200. Severity: high.
Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.
SEAT BELTS:FRONT:WEBBING
THE RAIL OF THE AUTOMATIC SHOULDER BELT CAN WEAR SUFFICIENTLY SUCH THAT THE CABLE WHICH RETRACTS THE BUCKLE ASSEMBLY WILL BECOME JAMMED IN THE RAIL RENDERING THE SHOULDER BELT INOPERATIVE.
SERVICE BRAKES, HYDRAULIC:POWER ASSIST:VACUUM:HOSES, LINES/PIPING, AND FITTINGS
OIL MIST CONTAINED IN THE ENGINE INTAKE AIR CAN COLLECT OVER TIME IN THE BRAKE VACUUM CHECK VALVE PREVENTING THE CHECK VALVE FROM OPENING AT THE SPECIFIED PRESSURE REDUCING POWER ASSIST TO THE BRAKES.
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The 13B's oil metering pump (OMP) injects small amounts of engine oil to lubricate the apex and side seals; on the FC it feeds the engine through thin plastic injection lines that become rock-hard and brittle with decades of heat, cracking or snapping when disturbed. A seized pum… Repairs typically run $200-$900. Severity: high.
The FC's Dynamic Tracking Suspension System (DTSS) uses deliberately compliant rubber bushings in the rear hub carriers so cornering loads passively steer the rear wheels (up to about one degree of toe change). After 30+ years these bushings deteriorate, and the calibrated compli… Repairs typically run $350-$1,000. Severity: medium.
The FC's factory ground points — especially the battery ground on the driver's shock tower, which sits exposed to wheel-well water and salt, and the ECU/engine grounds — corrode with age and starve the ECU and sensors of a clean reference. The classic result is the infamous '3,80… Repairs typically run $50-$300. Severity: medium.
Unlike later RX-7s, the FC fires its two trailing spark plugs through a dedicated pair of trailing coils and a separate igniter that selects T1 or T2 on the rising/falling edge of an ECU 'select' signal — a system distinct from the leading ignition. Age-failed trailing coils and… Repairs typically run $150-$600. Severity: medium.
All naturally aspirated FC RX-7s use Mazda's 6-port induction (6PI): two auxiliary intake ports per rotor stay closed below roughly 3,800 RPM, then rotating sleeves open them for top-end power. The vacuum/pressure-driven sleeve actuators and the sleeves themselves carbonize and s… Repairs typically run $150-$800. Severity: medium.