WABCO System Saver 318 User manual

NON-THROUGH DRIVE THROUGH DRIVE
SYSTEM SAVER 318 AIR
COMPRESSOR FOR MACK
E-TECH™ AND ASET™
ENGINES
MAINTENANCE MANUAL

Service Notes
Information contained in this publication was in effect at the time the publication
was approved for printing and is subject to change without notice or liability.
WABCO reserves the right to revise the information presented or to discontinue the
production of parts described at any time.
WABCO Maintenance Manual 31 (Revised 08-18)
About This Manual
This manual provides service and repair procedures for the WABCO
System Saver 318 air compressor.
Before You Begin
1. Read and understand all instructions and procedures before
you begin to service components.
2. Read and observe all Warning and Caution hazard alert
messages in this publication. They provide information that can
help prevent serious personal injury, damage to components,
or both.
3. Follow your company’s maintenance and service, installation,
and diagnostics guidelines.
4. Use special tools when required to help avoid serious personal
injury and damage to components.
Hazard Alert Messages and Torque
Symbols
WARNING
A Warning alerts you to an instruction or procedure that you
must follow exactly to avoid serious personal injury and
damage to components.
CAUTION
A Caution alerts you to an instruction or procedure that you
must follow exactly to avoid damage to components.
@This symbol alerts you to tighten fasteners to a specified torque
value.
How to Obtain Additional Maintenance
and Service Information
Visit Literature on Demand at meritor.com. WABCO publications are
also available on our website: wabco-na.com.
WABCO Customer Care
Call WABCO North America Customer Care at 855-228-3203.
How to Obtain Tools and Supplies
Specified in This Manual
Call Meritor’s Commercial Vehicle Aftermarket at 888-725-9355 to
obtain tools and supplies.

Contents
pg. 1 Section 1: Introduction
Application
Description
2Operation
Maintenance Intervals
Cylinder Head
3 Visual Inspection
4Section 2: Troubleshooting
7Section 3: Compressor Replacement
Compressor
Replacement Information
Removal
8 Installation
Cylinder Head
Removal
9 Installation
10 Testing
Air System Leakage Test

Notes

1 Introduction
1
WABCO Maintenance Manual 31 (Revised 08-18)
1 Introduction
Application
앫System Saver 318 non-through drive version air compressor
used on Mack engines. Figure 1.1.
앫System Saver 318 through-drive version air compressor used on
Mack engines. This unit is required to run hydraulic power
steering pumps. Figure 1.1.
앫Swept volume displacement: 18.7 cubic feet per minute.
앫Flange mounted to the engine.
— Coupling driven.
— Inlet air, oil lubrication and coolant supplied from the engine.
앫Pneumatic pressure signal from the governor controls
compression:
— Integrated pressure relief valve protects the compressor
and engine if discharge or governor lines become blocked,
or if compressor cannot unload. The valve prevents the
compressor from pumping above 250 psi in the event of
a blocked discharge line or other malfunction.
Figure 1.1
Description
The WABCO System Saver 318 air compressor provides and
maintains air under pressure to operate devices in the air brake and
auxiliary air systems of a vehicle. It consists of two major
subassemblies: Cylinder head and crankcase/cylinder block.
Figure 1.2.
Figure 1.2
The cylinder head contains the inlet, discharge and unloader
valving, as well as an integral relief valve. There are two water ports,
marked Port 9, an air discharge port, marked Port 2, and an inlet
port, marked Port 0. The cylinder head is mounted on the
crankcase/cylinder block.
The crankcase/cylinder block contains the cylinder bore, piston,
bearings, crankshaft, governor port and connecting rod.
Figure 1.1
1003372b
NON-THROUGH DRIVE THROUGH DRIVE
Figure 1.2
NON-THROUGH DRIVE THROUGH DRIVE
1003373b
CYLINDER
HEAD
CRANKCASE
(CYLINDER BLOCK)
CYLINDER
HEAD
CRANKCASE
(CYLINDER BLOCK)

1 Introduction
2WABCO Maintenance Manual 31 (Revised 08-18)
Operation
The compressor is driven by the engine and its crankshaft turns
continuously while the engine is running. Compression of air is
controlled by the governor and by the compressor’s unloading
mechanism.
The governor maintains the brake system air pressure at preset
maximum and minimum levels. The governor is mounted apart from
the compressor, either horizontally or vertically. The governor port is
located on the crankcase of the compressor. Figure 1.3.
Figure 1.3
The unloader mechanism controls the air compression cycle; an
air compression cycle has three phases:
1. Induction: Air flows from the engine to the compressor,
opening an inlet valve in the cylinder head of the compressor.
2. Compression: Air pressure is increased, causing the
compressor’s discharge valve to open.
3. Unloading: Air passes from the cylinder to the inlet chamber of
the cylinder head via a port controlled by a sliding leaf valve.
When system cut-in pressure is reached, air is exhausted from
the unloader port.
4. After unloading, the unloader piston returns the sliding leaf
valve to the loaded position. This seals the unloader ports and
compression resumes. Figure 1.4.
Figure 1.4
Maintenance Intervals
The WABCO System Saver 318 air compressor receives inlet air, oil
and coolant from the engine, so it is important to follow the engine
manufacturer’s recommendations and maintenance schedules
regarding fluid levels, air filter and recommended change intervals.
Cylinder Head
Remove carbon deposits from the discharge cavity and rust and
scale from the cooling passages of the cylinder head.
Clean carbon and dirt from the inlet and unloader passages.
NOTE: Shop air may be used to blow the carbon and dirt deposits
from the unloader passages.
Figure 1.3
GOVERNOR
PORT
1003374b
Figure 1.4
1003375b
SLIDING LEAF
VALVE

1 Introduction
3
WABCO Maintenance Manual 31 (Revised 08-18)
Visual Inspection
A visual check of the compressor can detect minor problems. This check should be part of the vehicle preventive maintenance program.
Figure 1.5.
Figure 1.5
Figure 1.5
1003376b
Check air inlet and
discharge ports
between compressor
and governor.
Check
under plate
or at power
steering
pump for
leakage.
Check water ports
for leakage.
Check
flanges
for cracks
or breaks.
Check air inlet and
discharge ports
between compressor
and governor.
NON-THROUGH DRIVE THROUGH DRIVE
Check
flanges
for cracks
or breaks.

2 Troubleshooting
4WABCO Maintenance Manual 31 (Revised 08-18)
2 Troubleshooting
Hazard Alert Messages
Read and observe all Warning and Caution hazard alert messages in this publication. They provide information that can help prevent serious
personal injury, damage to components, or both.
WARNING
To prevent serious eye injury, always wear safe eye protection when you perform vehicle maintenance or service.
Use Table A to troubleshoot the WABCO System Saver 318 air compressor.
NOTE: If you have any questions or need additional information, please contact WABCO North America Customer Care at 855-228-3203.
Table A: Compressor Troubleshooting Guide
Condition Possible Cause Solution
Compressor passes
excessive oil (for example,
the presence of oil at
exhaust air brake system
valves, oil in air dryer
desiccant, etc.)
Blocked or restricted oil return Clean oil drain passages in the compressor and on the engine
surface. Verify correct passage alignment.
Contaminated inlet air or oil Replace damaged, defective or dirty engine air filter.
Repair any leaking, damaged or defective compressor air intake
components.
Change engine lubricating oil.
NOTE: To avoid this condition, make sure vehicle manufacturer’s oil
and filter maintenance schedules are followed.
Restricted air inlet or excessive
vacuum present at compressor inlet
Verify engine or compressor air cleaner is functioning correctly.
Replace if necessary.
Repair compressor air inlet kinks or excessive bends.
Check vehicle specifications to ensure air and coolant lines meet all
requirements.
Excessive engine crankcase pressure Verify engine crankcase venting is to manufacturer’s specification.
Compressor duty cycle too high Check system for leaks. Make necessary repairs.
None of the above, but condition
persists
Replace the compressor.
Compressor leaks oil Physical damage or internal problems
with compressor
Replace the compressor.
Compressor continuously
cycles
Compressor unloader piston leaking With compressor unloaded, check for air leakage. If leaking, replace
the cylinder head.
Governor air leak Refer to the manufacturer’s manual for governor maintenance and
troubleshooting procedures.
Dryer purge valve air leakage Check for air dryer malfunction. Refer to air dryer manufacturer’s
service instructions.
Air leak at governor-compressor
attachment
Inspect connection for physical damage. Inspect and repair
connection.
Air leak at alcohol injector Clear line of any obstructions.
Inspect and repair connection.
Excessive reservoir contamination Drain reservoirs.
None of the above, but condition
persists
Replace the compressor.

2 Troubleshooting
5
WABCO Maintenance Manual 31 (Revised 08-18)
No air delivery
Low air delivery
Low air pressure
Discharge line blockage Check for freeze up in the discharge line.
Check low spots and eliminate any traps in the discharge line.
Inspect and repair compressor discharge port and clear any line
restrictions. Replace damaged lines as necessary.
Check for carbon build-up. If carbon has built up, make sure cooling
lines are not kinked or restricted. If carbon has built up in the
discharge line, replace the line.
Inlet line kinked or restricted Inspect the compressor air induction line for kinks and restrictions.
Repair or replace as necessary.
Governor malfunction or
misadjustment
Check for correct loader/unloader cycles of compressor.
Refer to vehicle manufacturer’s manual for governor maintenance and
troubleshooting procedures.
External contamination Replace broken, defective or dirty air filters. Clean contaminants from
surface of compressor.
Air dryer purge valve stuck open or
leaking
Check for air dryer malfunction. Refer to air dryer manufacturer’s
service instructions.
Chafed or worn discharge line Replace faulty sections of discharge line.
Loose or leaking air line connections Verify all connections are secure.
Tighten to vehicle specifications where necessary.
Inspect port threads for damage. If damage is extensive, replace
cylinder head.
Damage to compressor valves and/or
valve seats
Replace the cylinder head.
Leaking or malfunctioning internal
pressure relief valve
Replace the cylinder head.
Noisy air compressor Loose drive hub
Loose accessory drive coupling
Check fit of drive coupling.
Ensure hub is completely seated and crankshaft nut is tight.
Inspect crankshaft for damage — replace compressor if crankshaft is
damaged.
None of the above, but condition
persists
Replace the compressor.
Broken connecting rod or
crankshaft
Oil starvation to crank pin or front main
bearing
Check oil pressure. Verify oil passage is free of obstructions. Make
necessary repairs.
Failed power steering pump
(through-drive version only)
Verify power steering pump is in correct operating order. Refer to the
component manufacturer’s service instructions.
All of the above Replace compressor.
Condition Possible Cause Solution
Table A: Compressor Troubleshooting Guide

2 Troubleshooting
6WABCO Maintenance Manual 31 (Revised 08-18)
Compressor leaks engine
coolant
Loose fitting Check fittings at compressor and engine for leaks and verify fittings
are correctly torqued.
Cracked coolant port Replace cylinder head.
Porosity in cylinder head Replace cylinder head.
Leaking of gasket internal to the
cylinder head
Verify cylinder head bolts are correctly torqued. Make necessary
adjustments.
Inspect gasket for cracks or signs of wear. Replace if necessary.
Replace cylinder head.
None of the above, but condition
persists
Replace compressor.
Compressor pressurizes
coolant system or coolant
leakage to compressor
inlet
Leaking of gasket internal to the
cylinder head
Inspect gasket. Replace if necessary.
Cavitation or corrosion in cylinder
head
Replace cylinder head.
Porosity in cylinder head or cylinder
head cracked
Replace cylinder head.
None of above, but condition persists Replace the compressor.
Unloader leakage Possible internal damage, including
worn or damaged unloader piston
O-ring, porosity in unloader piston
bore, loose or leaking seal at unloader
piston bore
Replace compressor cylinder head assembly.
Compressor head gasket
failure
Discharge line blocked due to freezing
or carbon build-up
Check for trap (low spots) in lines.
Make necessary repairs.
Clear discharge line. Replace line if necessary.
Check for carbon build-up. If carbon build-up is present, replace the
discharge line.
Frozen or blocked line to governor Clear blocked line. Replace line if necessary.
Check for air dryer malfunction. Repair or replace as required. Refer
to the air dryer manufacturer’s maintenance manual for service
information.
Governor malfunction Repair or replace the governor. Refer to governor manufacturer’s
maintenance manual for service information.
Incorrect cylinder head bolt torque,
machining defect on cylinder head or
block, defective cylinder head gasket
Inspect gasket. Replace if necessary. Verify all bolts are correctly
torqued. If problem persists, replace cylinder head.
None of the above, but condition
persists
Replace compressor cylinder head assembly.
Condition Possible Cause Solution
Table A: Compressor Troubleshooting Guide

3 Compressor Replacement
7
WABCO Maintenance Manual 31 (Revised 08-18)
3 Compressor Replacement
Hazard Alert Messages
Read and observe all Warning and Caution hazard alert messages in
this publication. They provide information that can help prevent
serious personal injury, damage to components, or both.
WARNING
To prevent serious eye injury, always wear safe eye protection
when you perform vehicle maintenance or service.
Remove all pressure from the air system before you
disconnect any component. Pressurized air can cause serious
personal injury.
Park the vehicle on a level surface. Block the wheels to
prevent the vehicle from moving. Support the vehicle with
safety stands. Do not work under a vehicle supported only by
jacks. Jacks can slip and fall over. Serious personal injury and
damage to components can result.
Compressor
Replacement Information
The cylinder head portion of the compressor is replaceable.
The crankcase is not replaceable. If the crankcase is damaged
or malfunctioning, replace the complete compressor.
The front of the WABCO System Saver 318 air compressor is
mounted to the engine.
Before you remove the compressor, make sure you have a
replacement gasket to install with the new compressor, Mack
part number 590GB2159. Figure 3.1.
Figure 3.1
Removal
1. Park the vehicle on a level surface and set the parking brakes.
Block the wheels to prevent the vehicle from moving.
2. Drain the air pressure from the air system.
3. Drain the engine cooling system and the cylinder head of the
compressor.
4. Disconnect all air and water lines leading to the compressor.
5. Through-drive version air compressor only: If there is a
power steering pump installed at the back of the compressor,
remove the power steering pump. Figure 3.2. Disconnect the
power steering pump. Refer to the manufacturer’s manual for
specific information. It is not necessary to remove pumps
installed at the front of the compressor.
Figure 3.2
6. Remove the discharge and coolant fittings. Note fitting
locations to aid in assembly.
The removal instructions given in this manual are general.
Depending on the type of vehicle involved, additional steps may
be required. Refer to the vehicle manufacturer’s manual for
additional information.
Figure 3.1
Figure 3.2
1003382a
1003377a

3 Compressor Replacement
8WABCO Maintenance Manual 31 (Revised 08-18)
7. Loosen the three flange mounting bolts that hold the
compressor to the engine.
8. Remove the compressor from the vehicle.
Remove and retain the oil supply tube that runs between
the compressor and the engine. Figure 3.3.
Figure 3.3
Installation
1. Reinstall the oil supply tube.
2. Install a new compressor gasket.
3. Position the compressor on the engine.
4. Install the three flange mounting bolts. Tighten to 15 lb-ft
(20 Nm) +90rotation. @
5. Attach the discharge and coolant fittings. Tighten to 22 lb-ft
(30 Nm) +360maximum to position the fitting. @
6. Connect all air and water and lines leading to the compressor.
Tighten per Mack specifications.
7. Through-drive version air compressor only: If necessary,
reinstall the power steering pump. Refer to the manufacturer’s
maintenance manual to verify that the installation is to the
correct specifications.
8. Add engine coolant to the cooling system. Use the coolant
recommended by the engine manufacturer. Visually inspect the
engine and compressor for leaks.
9. Start the engine and allow the air system to build to governor
cutout. Stop the engine. Use a soap-and-water solution at
connection points to check for air leaks. Make any necessary
repairs.
10. Remove the wheel blocks. Release the spring (parking) brakes.
Cylinder Head
Removal
1. Remove the compressor from the engine. Refer to the
procedure in this section. Take care not to damage the
crankcase, since it will not be replaced.
2. Use a cleaning solvent to remove road dirt and grease from the
exterior of the compressor.
3. Remove the four bolts that attach the cylinder head to the
crankcase and remove the cylinder head. Figure 3.4.
Figure 3.4
4. Use a cleaning solvent to clean the top of the crankcase.
Figure 3.3
1003378b
OIL
SUPPLY
TUBE
Figure 3.4
Remove the four
bolts that attach
the cylinder
head to the
crankcase.
1003383b

3 Compressor Replacement
9
WABCO Maintenance Manual 31 (Revised 08-18)
Installation
NOTE: A Torxtool is required for this procedure.
Cylinder head valve components MUST be aligned in the correct
position in order for the compressor to function.
1. Align the hole in the cylinder head gasket with the unloader
passage on the top of the crankcase. Figure 3.5.
Figure 3.5
NOTE: A light application of engine oil will hold the sliding leaf
to the inlet valve.
2. Install the sliding leaf. The two holes in the sliding leaf must be
installed over the two pins on the base of the cylinder head.
Figure 3.6.
Figure 3.6
3. Position the inlet valve on the bottom of the cylinder head. Align
the large holes. Figure 3.7.
Figure 3.7
4. Position the cylinder head on top of the crankcase. Ensure the
notched pins on the cylinder head align with the recesses in
the block. Only two bolt holes have split alignment sleeves.
Figure 3.8.
Figure 3.8
Figure 3.5
Figure 3.6
CYLINDER
HEAD GASKET
1003384b
UNLOADER
PASSAGE
HOLE ALIGNMENT
1003386a
SLIDING LEAF
VALVE
Figure 3.7
Figure 3.8
1003385a
INLET
VALVE
1003379a
CYLINDER
HEAD
ALIGNMENT
SLEEVE
CYLINDER
HEAD
ALIGNMENT
SLEEVE

3 Compressor Replacement
10 WABCO Maintenance Manual 31 (Revised 08-18)
5. Install the four hex-head mounting bolts that hold the cylinder
head in place. Tighten the mounting bolts in sequence
(1 - 2 - 3 - 4) to 18.5 to /–2.5 lb-ft (25 to /–5 Nm). Then,
apply 90+15/–5rotation to the four cylinder head bolts.
Use an angular gauge to check the rotation. Figure 3.9. @
Figure 3.9
6. Use a Torxtool to tighten the five Torxhead screws in
sequence (5 - 6 - 7 - 8 - 9) to 4.4 lb-ft (6 0.6 Nm). Then,
apply an additional 90+15/–5rotation to the five Torx
head screws. Use an angular gauge to check the rotation.
Figure 3.10. @
Figure 3.10
7. Install the compressor and test for leaks. Refer to the
procedures in this section.
Testing
Test the vehicle air system as follows.
1. Bleed the vehicle air system reservoir gauges down to
approximately 85 psig. Apply brakes several times.
2. With the engine running at full governed speed, with no load or
air accessories being used, the compressor should reach
governor cutout pressure, then unload.
If the compressor does not reach governor cutout pressure,
check for air leaks in the system. If reservoir volume and
engine RPM are per original vehicle manufacturer’s
specifications, system plumbing leakage must be checked and,
if necessary, repaired. Refer to the air system leakage test
procedure in this section.
If the compressor fails to unload, verify correct governor
operation.
Air System Leakage Test
Conforms to North American Uniform Roadside Inspection
Criteria
1. Park the vehicle on a level surface. Apply the parking brakes.
Disconnect any attached or towed vehicles, semi-trailer, full
trailer, dolly, etc. Leave the engine on.
2. Chock the tires.
3. Release the parking brakes.
4. With the compressor in pumping mode, engine at idle and
service brakes fully applied, the gauge must stay between
80 to 90 psi, or gradually rise.
If pressure is not maintained, pressure drops, there is an air
leak in the system.
Listen for air leaks. Soapy water or high frequency acoustic
detectors may be used to detect air leaks. Make the necessary
repairs.
Figure 3.9
Figure 3.10
Tighten bolts
in sequence
shown.
Apply
90˚+15˚/–5˚
rotation.
14
32
90˚ +15˚/–5˚
1003380a
Tighten bolts
in sequence
shown.
Apply
90˚+15˚/–5˚
rotation.
67
85
9
90˚ +15˚/–5˚
1003381a

© 2018 WABCO North America – All rights reserved – MM31 / 08.2018
connects trucks, trailers, cargo,
drivers, business partners and
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ported sales of $2.8 billion in
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information, visit:
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leading global supplier of technol-
ogies and services that improve
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nectivity of commercial vehicles.
Founded nearly 150 years ago,
WABCO continues to pioneer
breakthrough innovations for ad-
vanced driver assistance, brak-
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the transportation industry as it
maps a route toward autonomous
driving, WABCO also uniquely