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MOTRS

RX-7 (SA/FB)

1978-1985 / Coupe / Japan

All RX-7 (SA/FB) problems All workshop issues
Minor Engine, Rotary-Specific Issues

Carbon Buildup

Symptoms

Hard carbon deposits accumulate on the rotor faces, apex seal grooves, and exhaust ports. The deposits restrict apex seal movement in their grooves, causing the seals to stick and lose their spring tension against the housing. Compression drops, power decreases, and the engine runs rough.

Cause

Short trips where the engine never reaches full operating temperature, low-rpm driving (the rotary needs revs to stay clean), and poor fuel quality all contribute to carbon buildup. The rotary engine is particularly susceptible because the combustion chamber shape and seal arrangement create areas where deposits accumulate.

Fix

Prevention is key, drive the car hard regularly, use quality fuel, and keep the engine at operating temperature.

For established deposits, an "Italian tune-up" (sustained high-rpm driving) can clear some buildup.

Severe cases require engine disassembly and manual cleaning.

Some owners use decarbonising additives, but these are controversial in the rotary community.

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Other known issues

Minor Engine, Rotary-Specific Issues

Apex Seal Wear and Failure

Gradual loss of compression, reduced power output, difficulty starting (especially when hot), increased oil consumption, and eventually the engine won't sustain combustion. In catastrophic failure, a broken apex seal fragment can score the rotor housing surface, requiring housing replacement.
Minor Engine, Rotary-Specific Issues

Rotor Housing Scoring

Deep scratches or grooves in the chrome or Nikasil coating of the rotor housing inner surface. Reduces compression even with new apex seals. Visible during engine disassembly.
Common Engine, Rotary-Specific Issues

Oil Metering Pump Failure

The engine receives insufficient oil for apex seal lubrication. The apex seals run dry, wear accelerates dramatically, and catastrophic engine failure follows. There may be no warning, the engine simply starts losing compression faster than normal.
Critical Engine, Rotary-Specific Issues

Coolant Seal (O-ring) Failure

Coolant leaks into the combustion chamber (white smoke from exhaust, coolant loss without external leak) or coolant leaks externally from the engine block mating surfaces. The engine overheats.
Minor Rust

Inner Guard Corrosion

The front inner guards corrode from trapped mud, moisture, and road debris. Rust perforates the inner guard panels, weakening the structural support for the front suspension mounts.
Minor Rust

Floor Pan Corrosion

The floor pans rust from underneath, often hidden by carpets and sound deadening. In severe cases, you can see the road through the floor. The floor provides structural rigidity to the unibody, perforated floors compromise the car's integrity.
View all 15 RX-7 (SA/FB) problems