Apex Seal Wear
Symptoms
Loss of compression, reduced power, difficulty starting (especially when cold), blue-white exhaust smoke, and eventually misfiring and inability to idle. A rotary engine with worn apex seals is an engine that needs a rebuild, there is no halfway measure.
Cause
The apex seals are the rotary equivalent of piston rings. They ride on the tips of the triangular rotor, sealing the combustion chamber against the epitrochoid housing. The 10A was Mazda's first production rotary, and the seal materials and housing coatings were first-generation technology. The seals are narrower than those used in the later 12A and 13B, and the housing surface treatments are less durable. Wear is inevitable, the question is how many kilometres the seals last before compression drops below usable levels.
Fix
Full engine rebuild with new apex seals, side seals, corner seals, and O-rings.
The housings must be inspected for scoring, if the chrome plating is damaged, the housings need re-plating (a specialist process available from a small number of firms worldwide).
An engine rebuild by a rotary specialist in Australia (Atkins Rotary, PAC Performance, or Promaz) will cost $5,000-10,000+ depending on housing condition.
Sourcing 10A-specific parts may add to this cost significantly.
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