Chevrolet 70 1969 Series, Shop Manual

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AIR COMPRESSORS AND GOVERNORS 6T-6
Figure 7— Installing Unloader Components (B-W)
Removal and Disassembly (Fig. 8)
1. Disconnect both ends of tube between
governor and unloader. Remove tube assembly.
2. Remove two bolts attaching unloader as­
sembly to cylinder head.
3. Remove unloader assembly. Remove inlet
valve plunger and plunger spring.
4. Remove bushing, valve, diaphragm, and
expander spring from body. Should difficulty be
encountered in removing these parts, apply air
pressure to body to force out these parts.
5. Remove the rubber retainer from the
bushing.
Figure 8 — Unloader Assembly (M-R)
plunger. Place each guide and plunger in position
above unloader piston, then push guide down over
top of piston.
3. Install unloader spring and spring saddle.
Make sure saddle rests squarely on top of plunger
guides, and make sure top of spring engages
spring seat in cylinder block.
4. Install new gasket at air inlet and connect
air inlet elbow.
M IDLAND- ROSS
The following procedure includes disassembly
and assembly instructions as well as removal and
installation. If a new unloader is being installed
omit the unnecessary steps.
Assembly and Installation (Fig. 8)
1. Apply thin film of light engine oil to bush­
ing, diaphragm, and body before assembly.
2. Install expander spring around inside of
diaphragm, then install these two parts in body.
3. Install rubber retainer on bushing.
4. Place valve in recess of bushing, then in­
stall in body.
5. Install plunger spring and inlet valve
plunger.
6. Set unloader assembly in place on cylinder
head and fasten with two bolts.
7. Connect tube assembly from unloader to
governor.
8. Test assembly with air pressure. Un­
loader should withstand a pressure of 100 psi
without leaking.
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L