1978 Mazda Cosmo Automatic TransFACTORY OEM SERVICE PROCEDURE

Engine Identification

Engine code is stamped on rear rotor housing, just rear of oil filter. Engine serial number is stamped on front rotor housing, behind distributor.

ENGINE CODES

Application Code
RX3 & RX3SP 12A
Cosmo, Pickup & RX4 13B
RX7 12A
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.

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