Brake Booster - DELCO Hydro-Boost: Disassembly

Secure booster mounting bracket in vise with pedal rod pointing down. Pump pedal rod until accumulator pressure is depleted.
WARNING: Accumulator contains compressed gas and injury may result if the following is not heeded: Wear safety glasses. Do not apply heat to accumulator. Do not attempt to repair accumulator. Replace with new assembly. Before disposing of an inoperative accumulator, drill a 1/8" hole through the end of can, opposite "O" ring. DO NOT drill through piston end.
Using special socket (J-25085), loosen Torx-head bolts securing front housing to rear housing. While holding front housing, remove Torx-head bolts. Have pan ready to catch and discard leaking fluid.
Use care when handling front housing as the accumulator contains a high rate spring in compression. Lift off front housing leaving spool valve and power piston/accumulator assembly attached to rear housing.
Remove output rod and piston return spring from power piston/accumulator assembly. Remove spool valve spring from valve. Remove output rod retainer assembly from front housing. Remove spool valve by rotating it out of lever arm. Remove and discard large "figure eight" seal from rear housing. Remove and discard power piston seal from bore.
Inspect spool valve and power piston for wear or scratches. Replace if necessary.
Remove power piston by cutting end of connecting pin. Push out pin with a small punch and remove piston. Clean all parts in power steering fluid.

NOTE: Whenever booster is disassembled all seals and damaged tube inserts should be replaced. All accumulator valve components must be replaced if any are lost or damaged. If the spool valve bore is damaged, the entire booster should be replaced as an assembly.