Bendix Commercial Vehicle Systems BA-921 SMC COMPRESSOR - Manual (Page 12)

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7. Install the safety valve (9) in the discharge safety valve
port (see Figure 9) of the cylinder head, then tighten to a
torque between 230 and 257 inch pounds (26 - 29 N•m).
PART TWO: UNLOADER INSTALLATION
1. Using the lubricant provided, lubricate the unloader
piston bores. Note: There are two bores that must be
lubricated.
2. The service kits contains a pre-lubed and pre-
assembled unloader piston assembly (7) which
includes the unloader piston, two o-rings, and guide
bushings. Remove the unloader piston assembly (7)
from the package, remove the plastic cap that retains
the upper bushing on the top of the piston. Using the
lubricant (8) provided, apply additional lubricant to the
two o-rings on the outside of the unloader piston and
the surrounding areas. Note: If an o-ring appears to be
twisted, manipulate it to remove any twists.
3. Insert the unloader piston assembly (7) into the pre-
lubed unloader cavity of the cylinder head. Take care
to avoid catching or snagging the edge of the two guide
bushings as the unit is installed in the unloader cavity
bores. If there is signifi cant resistance when installing
the unloader piston assembly into the unloader cavity
bores; remove it, adjust the position of the bushings and
re-install. Make certain the unloader piston assembly is
pushed completely into the unloader cavity; this will help
prevent possible snagging of the top guide bushing.
4. Using the lubricant (8) provided, thoroughly lubricate the
exterior of the balance piston (5), including the o-ring
groove. Thoroughly lubricate the balance piston o-ring
(6). This o-ring is brown in color. Install the balance
piston o-ring onto the balance piston (5) o-ring groove.
Note: If an o-ring appears to be twisted, manipulate it
to remove any twists.
5. Apply lubricant (8) onto the inside diameter of the
unloader piston.
6. Insert the return spring (3) into the unloader piston
assembly.
7. Install the balance piston (5) with balance piston o-ring
(6) into the unloader piston assembly by installing the
stem (small diameter) of the balance piston into the
return spring (3).
8. Position the unloader gasket (4) on the top of the
unloader cavity of the cylinder head. Make certain the
gasket is orientated such that the vent hole is exposed
and surrounded on the outside by the gasket material.
9. Position the unloader cover on top of the balance piston
making certain the stamped logo is visible.
10. Press and hold the unloader cover in place on the
cylinder head. Install both unloader cover cap screws.
Torque the cover cap screws (2) between 62 and 71
inch pounds (7-8 N•m).
INSTALLING THE COMPRESSOR
1. Apply a liquid gasket sealant to the compressor /
engine mounting interface (Refer to Figure 3 for
compressor mounting face). Follow the Engine or
Vehicle Manufacturers guidelines for the proper liquid
gasket sealant material and application procedure.
2. Position the compressor on the engine mounting face
making sure that the alignment pins on the crankcase
fi t inside the engine mounting face alignment pin holes.
3. Secure the compressor on the engine mounting
interface using the six mounting bolts. NOTE: There
are two short bolts and four long bolts. Be sure the use
the proper length bolt for the crankcase bolt holes. Run
each of the bolts down fi nger tight, making sure not to
smear the liquid gasket material on the sealing surface.
Once the bolts are all fi nger tight; tighten the mounting
bolts per Engine Manufacturers recommended torquing
sequence and torque requirements.
4. Install any supporting brackets on the compressor in
the same position(s) noted and marked during removal.
5. Inspect all air and coolant lines and fi ttings before
reconnecting them to the compressor. Make certain
o-ring seals are in good or new condition, the threads
are clean and the fi ttings are free of corrosion. Replace
as necessary.
6. Install the discharge and coolant fi ttings, if applicable, in
the same position on the compressor noted and marked
during disassembly. See the Torque Specifi cations for
various fi tting sizes and types of thread at the rear of
this manual. Tighten all hose clamps.
7. Before returning the vehicle to service, perform the
Service Tests specifi ed in this manual. Pay particular
attention to all lines and hoses disconnected during
maintenance and check for air, oil, and coolant leaks
at compressor connections and the compressor engine
interface. Also check for noisy operation.