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  • High line pressure
  • Low line pressure
  • Harsh shifts
  • Overheated converter
  • Blued converter
  • Loss of cooler flow
  • No cooler flow


The constant oscillation of the pressure regulator valve results in bore wear, which allows leakage of valuable oil and improper functioning of the valve.


The Sonnax oversized pressure regulator valve eliminates leakage of both balance oil and line pressure that can occur when the valve body becomes worn.


Required tool kit 74846-RM is no longer in production. Check with your distributor for availability.


Oversized Pressure Regulator Valve
Part No. 74846-05

You need this if... View Instructions

Mazda vehicles with a G4A-EL, G4A-HL or GF4A-EL transmission may have problems with low line pressure, high line pressure, harsh shifts, lack of cooler flow, and/or blued converters. Many times these complaints can be traced back to a worn valve body bore at the pressure regulator valve. If line balance or cutback feed pressure is allowed to leak, the valve can't regulate line pressure, so pressures remain high. TV balance pressure reduces line pressure in second, third and fourth gears, so leaks at these spool diameters can cause harsh shifts. If the bore is worn at the line pressure passage, valuable line pressure may exhaust to sump. Sonnax has developed an oversized pressure regulator valve 74846-05 for the these applications.

  • The spring seat on the valve has been modified to compensate for the oversized valve and also provides higher line pressure at idle

Must measure OE valve small diameter before reaming. OE must be .357" It is highly recommended that the pressure modifier valve bore be checked for wear on the GF4A-EL unit as well. Wear at this bore can result in erratic shift quality and high/low line and EPC pressures. Sonnax offers an oversized pressure modifier valve, 74846-04, which can be used to refurbish bore wear at this location.

September 30, 2005

Anatomy of a Transmission: Oil Flow in the Pump-PR-Converter-Cooler Lube Circuits

Gregg Nader

Topics: Diagnostics And Theory Transmission

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  • 74846 05

You need this if...

A vacuum test at the port indicated fails to hold at least 16 in-Hg.

  • 74846 05 test