Hydro-Boost U Nit - Chevrolet LIGHT DUTY TRUCK (SERIES 10-35) Service Manual

Spool V alve Plug
Removal
1 . Turn engine off and pump brake pedal 4 or 5 times
to deplete accumulator.
2. Remove two nuts from master cylinder, then move
master cylinder away from booster with brake lines
attached.
3. Push spool valve plug in and use a small screwdriver
to remove retaining ring (fig. 5-53).
4. Remove spool valve plug and "O" ring.
Installation
1. Install "O" ring and spool valve plug (fig. 5-53).
2. Push spool valve plug in and install retaining ring.
3. Install master cylinder and two nuts to booster.
CAUTION: See "Caution" on Page 1 of
this section.
4. Bleed system.
BLEEDIN G PROCEDURE".
Tube S eat
Replacement
1. Turn engine off and pump brake pedal 4 or 5 times
to deplete accumulator.
2. Clean dirt around fitting before removing fitting,
then disconnect pressure hose at Hydro-Boost and secure
hose in a raised position to prevent loss of fluid.
3. To prevent metal chips from entering booster, pack
inside of tube seat with petrolatum.
4. Remove tube seat using No. 4 easy-out as shown in
Figure 5-54.
5. Wipe petrolatum from housing and clean housing
thoroughly to remove any metal chips or dirt.
6 . Install tube seat with Tool J-6217 as shown in Figure
5-55.
7. Fill and bleed system. Refer to "HYDRO-BOOST
BLEEDIN G PROCEDURE".

Hydro-Boost U nit

Replacement (fig. 5-56)
1 . Depress and release the brake pedal several times
(engine not running) to be sure that all pressure is
discharged from the accumulator prior to disconnectiong
the hoses from the booster.
2 .
P30(32) Models-
3. Clean all dirt from the booster at the hydraulic line
connections and master cylinder.
4. Remove the nuts and lockwashers that secure the
master cylinder to the booster and the support bracket.
Support the master cylinder, being careful to avoid kinking
or bending the hydraulic lines attached to the master
cylinder. Cover the end of the master cylinder with a clean
BRAKES 5-45
Refer to "HYDRO-BOOST
Raise the vehicle on a hoist.
LIGHT TR U CK SER V IC E M ANUAL