• Pressure loss
  • TCC apply concerns
  • Burnt clutches
  • Harsh shifts
  • Soft shifts


Damaged, deformed and/or eroded end plugs and bores allow loss of critical hydraulic pressure.


Recover hydraulic control and renew crucial circuit pressures by installing Sonnax O-ringed end plug kit.

4L80-E, 4L85-E

O-Ringed End Plug Kit
Part No. 34200-05K

TCC & PR Valves

Find a Distributor

OE end plugs are designed to prevent critical pressure loss by capping the bore, while also functioning as a valve stop. Repetitive spring motion, valve impact and fluid pressure variations cause wear between the end plug and bore mating surface, allowing vital pressure to escape the circuit. GM 4L80-E and 4L85-E pumps have end plugs at the pressure regulator and TCC shift valves that seal signal oil required to stroke the valve. When excess wear occurs at the end plugs, the result can be shifting problems, loss of gear and/or converter-related concerns.

Stop leaks and revive line pressure and TCC operation by installing Sonnax O-ringed end plug kit 34200-05K.

  • Minimal end-plug-to-bore clearance with added O-ring for positive seal
  • Reduces or eliminates leakage in eroded OE bores
  • End Plugs (5)
  • O-Rings (5)
  • Dia.: 0.625"
  • 4L80-E, 4L85-E O-Ringed End Plug Kit 34200-05K