What are the most common Mazda RX-7 problems?
According to Au7o's analysis of 280+ owner reports, the 1990 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.
Is the Mazda RX-7 reliable?
The 1990 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.
How much does it cost to fix common Mazda RX-7 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.
What is the 1990-1995 Mazda RX-7 Overheating and Coolant System Weakness?
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.
What is the 1987-1991 Mazda RX-7 Turbo II Wastegate Flapper Undersizing — Boost Creep and Overboost?
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.
What is the 1986-1991 Mazda RX-7 Oil Metering Pump Neglect and Brittle Injection Lines — Apex Seal Starvation?
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.
What is the 1986-1991 Mazda RX-7 DTSS Rear Toe-Control Bushing Wear — Vague, Self-Steering Rear End?
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.
What is the 1986-1991 Mazda RX-7 Degraded Chassis and Engine Grounds — the 3,800 RPM Hesitation?
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.
What is the 1986-1991 Mazda RX-7 Trailing Ignition Drop-Out (Twin Trailing Coils, Igniter, and Select Signal)?
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.
What is the 1986-1991 Mazda RX-7 5th/6th Auxiliary Intake Port Sleeve and Actuator Seizure (NA 6-Port Induction)?
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.
