Symptoms:

  • Clutch & band failures
  • Loss of lube oil
  • Low line pressure
  • High line pressure
  • Soft shifts
  • Harsh shifts
  • Low converter pressure

Cause:

Continuous oscillation of pressure regulator valve results in excess bore wear, causing erratic line pressure and/or restricting converter feed oil.

Correction:

Recover hydraulic control and renew line pressure performance by reconditioning the bore and installing Sonnax oversized pressure regulator valve kit.

You need this if...

Vacuum test(s) at the port(s) indicated fail to hold the recommended minimum in-Hg.

4F27E, FN4A-EL, FNR5, FS5A-EL Oversized Pressure Regulator Valve Kit Vacuum Test Locations