1966 Mercury Commuter 6.4L Eng VIN P, Automatic TransFACTORY OEM SERVICE PROCEDURE

Engine Code Designation: Notes

Fifth figure of "Vehicle Warranty Number" on car patent plate identifies engine as follows:

Engine Code Letter
289" 2-Bbl. 200 HP (1) C
390" 2-Bbl. 265 HP Synchro-mesh Y
Β  Β  275 HP Auto. Trans. H
Β  4-Bbl. 335 HP S
410" 4-Bbl. 330 HP M
428" 4-Bbl. 345 HP (2) Q
Β  Β  Police P
(1) Low compression 3Β  .
(2) Low compression 8Β  .
Factory Service Tools

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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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