K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Fig. 8 Exploded View Of Delco-Moraine Tandem Diaphragm Brake Booster Components
1.
Remove boot, silencer, vacuum check valve, grommet and front housing seal Fig. 8.
2.
Scribe a line across front and rear housing, then install brake booster to brake mounting fixture tool No. J 23456 or equivalent, Fig. 4.
3.
Turn fixture handle to unlock housings.
4.
Remove return spring, power piston assembly and power piston bearing from rear housing, Fig. 8.
5.
Remove piston rod, reaction retainer and power head silencer, Fig. 8.
6.
Remove power piston and pushrod assembly as follows:
a.
While holding the pushrod down against a hard surface, grasp outside edge of diaphragm support and diaphragm, Fig. 8.
b.
Use a slight force to dislodge diaphragm retainer, Fig. 8.
7.
Remove primary diaphragm and primary support plate from housing divider, Fig. 8.
8.
Remove primary diaphragm from primary support plate, Fig. 8.
9.
Remove secondary diaphragm and secondary support plate from housing divider, Fig. 8.
10.
Remove secondary piston bearing from housing divider, Fig. 8.
11.
Remove secondary diaphragm from secondary support plate, Fig. 8.
12.
Remove reaction body retainer, reaction body, reaction disc and reaction piston from reaction body, Fig. 8.
13.
Remove air valve spring and reaction bumper from end of air valve pushrod, Fig. 8.
14.
Remove retaining ring from air valve pushrod assembly.
15.
Remove air valve pushrod assembly by inserting a screwdriver through the pushrod eyelet and pulling pushrod assembly straight out.
16.
Remove filter, retainer and O-ring from air valve pushrod assembly.
17.
Inspect all parts for corrosion, nicks, cracks, cuts, scoring, distortion or excessive wear. Replace as necessary.
18.
Clean all parts in denatured alcohol and dry with clean compressed air. Do not immerse power piston and pushrod assembly in alcohol.
Assembly
1.
Install lubricated O-ring onto air valve pushrod assembly.
2.
Install air valve pushrod into the power piston.
3.
Install retainer and seat.
4.
Install filter over pushrod eyelet and into power piston.
5.
Install retaining ring onto air valve pushrod assembly.
6.
Install reaction bumper, air valve spring, reaction piston and reaction disc onto reaction body.
7.
Install reaction body, then reaction body retainer.
8.
Lubricate inside diameter of secondary diaphragm lip, inside diameter of primary diaphragm lip and the secondary piston bearing with a thin layer
of silicone grease.
9.
Install secondary diaphragm into the secondary support plate, Fig. 8.
10.
Install secondary diaphragm and secondary support plate over the power piston and pushrod assembly.
11.
Install secondary piston bearing into housing divider with flat surface of bearing on the same side as the six raised lugs on the divider.
