• Erratic line pressure
  • High line pressure
  • Low line pressure
  • Clutch slippage
  • Harsh shifts
  • Low cooler flow
  • No cooler flow
  • Overheated transmission
  • Soft shifts
  • Converter concerns


Continuous oscillation of pressure regulator valve results in excess bore wear, causing erratic line pressure and/or restricting cooler/lube flow.


Recover hydraulic control and renew line pressure performance by installing Sonnax drop-in pressure regulator valve kit.

6L45, 6L50, 6L80, 6L90

Pressure Regulator Valve Kit
Part No. 104520-14K

You need this if... View Instructions Find a Distributor

GM 6L45, 6L50, 6L80 and 6L90 units may exhibit multiple line pressure and cooler/converter/lube flow problems due to excess wear in the pressure regulator bore. Deterioration at the balance spool end allows critical fluid loss, resulting in high line pressure, harsh shifts and overheating due to reduced cooler/converter flow. Wear at the outboard spool robs converter feed pressure and lowers line pressure, resulting in soft shifts and burnt clutches. Installing Sonnax pressure regulator valve kit 104520-14K restores the hydraulic integrity of these circuits for proper line pressure control in all ranges. A new pressure regulator valve outer spring is also included to replace weakened original springs and provides a modest 5 psi increase across the pressure curve.

  • Hardcoat anodized aluminum valve combats premature wear
  • Lengthened critical spools operate in non-worn portion of bore for added stability and wear prevention
  • Annular grooves help center valve in bore to reduce future side-load wear
  • Replacement spring provides modest 5 psi line pressure increase
  • Drop-in Zip Valve™ parts install quickly and easily
Learn More About Zip Valve™ Drop-In Repairs

Pump must be removed to install kit.

  • Valve
  • Spring
  • Drill Bit .040"
  • Checkballs (2) 1 Extra

Sonnax valve body layouts provide a detailed overview of individual units making it quick and easy to determine what’s available for the specific valve body you’re working on. See all Sonnax valve body layouts.

GM 6L45, 6L50, 6L80, 6L90 Valve Body Layout

GM 6L45, 6L50, 6L80, 6L90 Valve Body Layout
  • 6L45, 6L50, 6L80, 6L90 Pressure Regulator Valve Kit 104520-14K
  • 6L45, 6L50, 6L80, 6L90 Pressure Regulator Valve Kit 104520-14K


6L80 Series Pressure Regulator Valve Repairs: Pump Drilling Explained
6L80 Series Pump Drilling Tips: How to Make Your Own Small Drill Bit Vise

You need this if...

Vacuum testing at the port(s) indicated fails to hold the recommended minimum in-Hg, or if wear is visually detected.

6L45, 6L50, 6L80, 6L90 Pressure Regulator Valve Kit Vacuum Test Locations