Bendix Commercial Vehicle Systems BA-921 SMC COMPRESSOR - Manual (Page 11)

11
4. If the unloader assembly has been removed from the
cylinder head, the unloader assembly must be serviced
using an unloader kit. (See Maintenance Kits, page 9.)
5. If large amounts of carbon build-up are present on the
unloader piston (7) seat or orifi ce or if the return spring
exhibits compression set, the unloader components
must be replaced with an unloader kit.
6. Carefully inspect the 2 bores in the unloader cavity of
the cylinder head for gouges or material transfer. If this
is detected, the compressor should be replaced.
REAR END COVER
Visually inspect for cracks and external damage. Check the
crankshaft rear bearing diameter in the rear end cover for
excessive wear, fl at spots or galling. Check the hydraulic
pump attachment pilot and threaded holes for damage.
Minor thread chasing is permitted, but do not re-cut the
threads. If any of these conditions are found, replace the
compressor.
CRANKCASE
Check the cylinder head gasket surface on the deck (top)
of the crankcase for nicks, gouges, and marring. A metal
gasket is used to seal the cylinder head to the crankcase.
This surface must be smooth and free of all but the most
minor scratching. If excessive marring or gouging is
detected, the compressor must be replaced.
Check the condition of the countersunk hole on the deck
of the crankcase that retains the o-ring and prevents
coolant leakage between the valve plate assembly and the
crankcase. The surface in contact with the o-ring should
be smooth and free of any scratches and gouges that could
causes leakage around the o-ring.
ASSEMBLY
General Note: All torques specifi ed in this manual are
assembly torques and typically can be expected to fall off
after assembly is accomplished. Do not re-torque after
initial assembly torques fall unless instructed otherwise.
A compiled listing of torque specifi cations is presented on
page 13.
INCH POUNDS TO FOOT POUNDS
To convert inch pounds to foot pounds of torque, divide
inch pounds by 12.
Example: 12 Inch Pounds = 1 Foot Pound
12
FOOT POUNDS TO INCH POUNDS
To convert foot pounds to inch pounds of torque, multiply
foot pounds by 12.
Example: 1 Foot Pound x 12 = 12 Inch Pounds
CRANKCASE FRONT COVER
1. Position the new cover over the hole in the front of the
crankcase. Using a rubber mallet, drive the cover into
the hole in the front of the crankcase, until the outside
diameter of the cover is fl ush with cast surface.
REAR END COVER
1. Install the o-ring (10) on the rear end cover.
2. Orient the rear end cover to the crankcase using the
reference marks made during disassembly. Carefully
install the rear end cover in the crankcase making
certain not to damage the crankshaft bearing surface.
3. Install the two end cover cap screws. Refer to Figure
10 to assure that the two cap screws are installed in
the proper crankcase bolt holes. “Snug” the screws
then tighten to 195 to 212 inch pounds (22-24 N•m).
CYLINDER HEAD ASSEMBLY
PART ONE: HEAD INSTALLATION
1. Note the position of the protruding alignment pins on
the deck (top) of the crankcase. Install the metal inlet
reed valve/gasket (1) over the alignment pins on the
crankcase.
2. Position the valve plate assembly on the crankcase
so that the alignment pins in the crankcase fi t into the
corresponding holes in the valve plate assembly.
3. Position and install one of the embossed metal gaskets
(2) over the alignment bushings protruding from the
cooling plate. Position and install the second embossed
metal gasket (2) over the alignment bushings on the
opposite side of the cooling plate. When properly
installed, the outline of the two embossed gaskets
match the outline of the cooling plate.
4. Install the cooling plate onto the valve plate assembly
by lining up the alignment bushings on the cooling plate
over the oversized countersunk holes of the valve plate
assembly. Again, when properly installed, the outline of
the cooling plate matches the outline of the valve plate.
5. Position and install the cylinder head over the alignment
bushings protruding from the cooling plate. When
properly installed, the outline of the cylinder head
assembly will match the outline of the cooling plate and
valve plate assembly.
Note: The alignment bushings will only fi t into two of
the cylinder head bolt holes.
6. Install the six hex head cylinder head bolts and washers
and snug them (fi nger tight), then torque the bolts in
the sequence specifi ed in Figure 11. Note: A light fi lm
of oil should be applied to the thread of these bolts prior
to installation. Oil should not be applied to any other
bolts.