Apex Seal Wear
Symptoms
Gradual loss of compression, resulting in reduced power, increasingly difficult cold starts, blue-white exhaust smoke (burning oil), and eventually rough idle, misfiring, and inability to maintain running at low RPM.
Cause
The 10A uses 2mm-wide apex seals, the narrowest of any production Mazda rotary. These seals ride on the tips of each triangular rotor, pressed against the epitrochoid housing by spring tension and combustion gas pressure. The seal material and the housing surface coating were first-generation technology. Wear is accelerated by inadequate lubrication (failed oil metering pump), overheating, cold starting with extended cranking, and short-trip driving that never allows the engine to fully warm up.
Fix
Full engine disassembly and rebuild.
New apex seals, side seals, corner seals, and all O-rings.
Housings must be inspected for scoring, if the chrome coating is damaged, the housings need replating (a specialist process).
A 10A rebuild at a rotary specialist costs $4,000-8,000 depending on housing condition.
Parts availability for the 10A is tighter than for the 12A or 13B, so allow extra time for sourcing.
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