BENDIX TU-FLO 700 User Manual

®

Bendix® TU-FLO® 700 Air Compressor

SD-01-335

EXTERIOR

DISCHARGE

DISCHARGE

VALVE SEAT

INLET

VALVE

SPRING

PISTON

CRANKSHAFT

CONNECTING

ROD

CRANKCASE

VALVE

INLET

VALVE

RINGS

PISTON

DISCHARGE

CAP NUT

DISCHARGE

VALVE

SPRING

UNLOADER

MECHANISM

BENDIX® TU-FLO® 700 AIR COMPRESSOR

(CROSS SECTION)

DESCRIPTION

The function of the air compressor is to provide and main­tain air under pressure to operate devices in the air brake
and/or auxiliary air systems

The Tu-Flo® 700 compressor is a two cylinder, single stage,
reciprocating compressor with a rated displacement of 15.5
cubic feet of air per minute at 1250 R.P .M. The Tu-Flo® 700
compressor is constructed from three major assemblies,
the head, the cylinder block and the crankcase.

The head houses the discharge valving and is installed on
the upper portion of the cylinder block. The cylinder block
contains the cylinder bores and inlet valves and is mounted
to the crankcase. The crankcase houses the crankshaft
and main bearings.

V arious mounting and drive configurations, required by the
numerous vehicle engine designs, are available. Two
governor mounting pads are located on either side of the
cylinder block to provide convenient governor mounting.

Two methods are employed for cooling the Tu-Flo® 700
compressor during operation. The cylinder head is
connected to the engine’s cooling system, while the cylinder
has external fins for efficient air cooling.

All Tu-Flo® 700 compressors utilize the engine’s pressurized
oil system to lubricate the internal moving parts. A nameplate
is attached to the crankcase to identify the compressor.
The nameplate displays a Bendix piece number or in some
cases an engine or vehicle manufacturer’s piece number,
along with a serial number.

TU-FLO 700

BW
NO.

SER

MANUFACTURED BY

BENDIX

NO.

COMPRESSOR NAMEPLATE

1

MACK

"FOXHEAD"

CUMMINS

VARIOUS COMPRESSOR MOUNTINGS

MACK

OPERATION

The compressor is driven by the vehicle engine and is
operating continuously while the engine is running. Actual
compression of air is controlled by the compressor unloading
mechanism and the governor. The governor is generally
mounted on the compressor and maintains the brake system
air pressure to a preset maximum and minimum pressure
level.

INTAKE AND COMPRESSION OF AIR (LOADED)

During the down stroke of the piston, a slight vacuum is
created between the ton of the piston and the head, causing
the flat circular inlet valve to move up and off its seat. (Note
the flat square discharge valve remains on its seat.)
Atmospheric air is drawn through the air strainer by the open
inlet valve and into the cylinder (see Fig. 2). As the piston
begins its upward stroke, the air that was drawn into the
cylinder on the down stroke is being compressed. Air
pressure on top of the inlet valve plus the force of its spring,
returns the inlet valve to its seat. The piston continues the
upward stroke and compressed air then flows by the open
discharge valve, into the discharge line and on to the
reservoirs (see Fig. 3). As the piston reaches the top of it s
stroke and starts down, the discharge valve spring and air
pressure in the discharge line returns the discharge valve to
its seat. This prevents the compressed air in the discharge
line from returning to the cylinder bore as the intake and
compression cycle is repeated.

NON-COMPRESSION OF AIR (UNLOADED)

When air pressure in the reservoir reaches the cut-out setting
of the governor, the governor allows air to pass from the

DETROIT

DIESEL

reservoir into the cavity beneath the unloader pistons. This
lifts the unloader pistons and plungers. The plungers move
up and hold the inlet valves off their seats (see Figure 4).

With the inlet valves held off their seats by the unloader
pistons and plungers, air is pumped back and forth between
the two cylinders. When air is used from the reservoir and
the pressure drops to the cut-in setting of the governor , the
governor closes and exhausts the air from beneath the
unloader pistons. The unloader saddle spring forces the
saddle, pistons and plungers down and the inlet valves return
to their seats. Compression is then resumed.

COMPRESSOR & THE AIR BRAKE SYSTEM

GENERAL

The compressor is part of the total air brake system, more
specifically, the charging portion of the air brake system. As
a component in the overall system its condition, duty cycle,
proper installation and operation will directly affect other
components in the system.

Powered by the vehicle engine, the air compressor builds
the air pressure for the air brake system. The air compressor
is typically cooled by the engine coolant system, lubricated
by the engine oil supply and has its inlet connected to the
engine induction system.

As the atmospheric air is compressed, all the water vapor
originally in the air is carried along into the air system, as
well as a small amount of the lubricating oil as vapor. If an
air dryer is not used to remove these contaminants prior to
entering the air system, the majority , but not all, will condense
in the reservoirs. The quantity of contaminants that reach
the air system depends on several factors including

2

Discharge
Line

Optional “Ping” T ank

Air Dryer

The Air Brake Charging System supplies the

compressed air for the braking system as well as other air
accessories for the vehicle. The system usually consists
of an air compressor, governor, discharge line, air dryer ,
and service reservoir.

Compressor

Governor

(Governor plus Synchro valve

for the Bendix

FIGURE 1A - SYSTEM DRAWING

®

DuraFlo™ 596

Compressor)

installation, maintenance and contaminant handling devices
in the system. These contaminants must either be eliminated
prior to entering the air system or after they enter .

DUTY CYCLE

The duty cycle is the ratio of time the compressor spends
building air to the total engine running time. Air compressors
are designed to build air (run "loaded") up to 25% of the
time. Higher duty cycles cause conditions that affect air
brake charging system performance which may require
additional maintenance. Factors that add to the duty cycle
are: air suspension, additional air accessories, use of an
undersized compressor, frequent stops, excessive leakage
from fittings, connections, lines, chambers or valves, etc.
Refer to T able A in the Troubleshooting section for a guide to
various duty cycles and the consideration that must be given
to maintenance of other components.

Optional Bendix® PuraGuard® QC

™

Oil Coalescing Filter

Service Reservoir

(Supply Reservoir)

Reservoir Drain

The discharge line must maintain a constant slope down
from the compressor to the air dryer inlet fitting or reservoir
to avoid low points where ice may form and block the flow . If,
instead, ice blockages occur at the air dryer or reservoir
inlet, insulation may be added here, or if the inlet fitting is a
typical 90 degree fitting, it may be changed to a straight or
45 degree fitting. Shorter discharge line lengths or insulation
may be required in cold climates.

While not all compressors and charging systems are
equipped with a discharge line safety valve this component
is recommended. The discharge line safety valve is installed
in the cylinder head (Tu-Flo® 550/750) or close to the
compressor discharge port and protects against over
pressurizing the compressor in the event of a discharge line
freezeup.

COMPRESSOR INST ALLA TION

While the original compressor installation is usually
completed by the vehicle manufacturer, conditions of
operation and maintenance may require additional
consideration. The following presents base guidelines.

DISCHARGE LINE

The discharge line allows the air, water-vapor and oil-vapor
mixture to cool between the compressor and air dryer or
reservoir. The typical size of a vehicle's discharge line, (see
column 2 of T able A in the Troubleshooting section) assumes
a compressor with a normal (less than 25%) duty cycle,
operating in a temperate climate. See Bendix and/or other
air dryer manufacturer guidelines as needed.

HOLE

THREAD

FIGURE 1B - DISCHARGE LINE SAFETY VALVE

3

DISCHARGE LINE TEMPERA TURE

When the temperature of the compressed air that enters
the air dryer is within the normal range, the air dryer can
remove most of the charging system oil. If the temperature
of the compressed air is above the normal range, oil as oil­vapor is able to pass through the air dryer and into the air
system. Larger diameter discharge lines and/or longer
discharge line lengths can help reduce the temperature.

The air dryer contains a filter that collects oil droplets, and a
desiccant bed that removes almost all of the remaining water
vapor. The compressed air is then passed to the air brake
service (supply) reservoir. The oil droplets and the water
collected are automatically purged when the governor
reaches its "cut-out" setting.

DISCHARGE

VALVE

PISTON

TO RESERVOIR

INLET VALVE

UNLOADER

PLUNGER

INTAKE

STRAINER

TO GOVERNOR

STROKE

For vehicles with accessories that are sensitive to small
amounts of oil, we recommend installation of a Bendix
PuraGuard® QC™ oil coalescing filter, designed to minimize
the amount of oil present.

LUBRICATION

Since all Tu-Flo® 700 compressors are connected to the
engine’s pressurized oil system, a continuous flow of oil is
provided to the compressor, which is eventually returned to
the engine. Oil is fed into the compressor in various ways,
for example: through the rear end cover, the drive end of the
crankshaft or through the front flange adapter . An oil passage
in the crankshaft conducts pressurized oil to the precision
sleeve main bearings and to the connecting rod bearings.
Splash lubrication of the cylinder bores, connecting rod wrist
pin bushings, and the ball type main bearings, on some
models, is obtained as oil is forced out around the crankshaft
journals by engine oil pressure.

Check the exterior of the compressor for the presence of oil
seepage and refer to the TROUBLESHOOTING section for
appropriate tests and corrective action.

FIGURE 2 - INTAKE

®

DISCHARGE

VALVE

PISTON

FIGURE 3 - COMPRESSION

TO RESERVOIR

INLET VALVE

UNLOADER

PLUNGER

INTAKE

STRAINER

TO GOVERNOR

STROKE

OIL P ASSING

All reciprocating compressors currently manufactured will
pass a minimal amount of oil. Air dryers will remove the
majority of oil prior to entrance into the air brake system.
For particularly oil sensitive systems the Bendix® PuraGuard
QC™ oil coalescing filter can be used in conjunction with a
Bendix air dryer.

If compressor oil passing is suspected, refer to the
TROUBLESHOOTING section and TABLE A for the
symptoms and corrective action to be taken. In addition,
Bendix has developed the "Bendix Air System Inspection
Cup" or BASIC test to help substantiate suspected excessive
oil passing. The steps to be followed when using the BASIC
test are presented in APPENDIX A at the end of the
TROUBLESHOOTING section.

4

DISCHARGE

®

VALVE

PISTON

FIGURE 4 - UNLOADING

TO RESERVOIR
INLET VALVE

UNLOADER

PLUNGER

INTAKE

STRAINER

TO GOVERNOR

STROKE

COOLING

Air flowing through the engine compartment from the action
of the engine’s fan and the movement of the vehicle assists
in cooling the crankcase. Coolant flowing from the engine’s
cooling system through connecting lines enters the
compressor and flows through the internal passages in the
cylinder block and head and back to the engine. Proper
cooling is important in maintaining discharge air temperatures
below the 400°F recommended maximum.

PREVENTIVE MAINTENANCE

Regularly scheduled maintenance is the single most
important factor in maintaining the air brake charging system.
Refer to T able A in the Troubleshooting section for a guide to
various considerations that must be given to the maintenance
of the compressor and other related charging system
components.

Important Note: Review the warranty policy before
performing any intrusive maintenance procedures. An
extended warranty may be voided if intrusive maintenance
is performed during this period.

DRY ELEMENT—PLEATED PAPER AIR
STRAINER

Every 20,000 miles or 800 operating hours:

Remove the spring clips from either side of mounting baffle
and remove the cover. Replace the pleated p aper filter and
remount the cleaned cover making sure the filter is in
position. Be sure to replace the air strainer gasket if the
entire air strainer is removed from the compressor intake.
(Note: Some compressors are fitted with compressor intake
adapters which allow the compressor intake to be connected
to the engine air cleaner.) In this case, the compressor
receives a supply of clean air from the engine air cleaner.
When the engine air filter is changed, the compressor intake
adapter should be checked. If it is loose, remove the intake
adapter, clean the strainer plate, if applicable, and replace
the intake adapter gasket, and reinstall the adapter securely .
Check line connections both at the compressor intake
adapter and at the engine air cleaner . Inspect the connecting
line for ruptures and replace it if necessary .

Every month, 300 operating hours or after each 10,000 miles,
depending on the operating conditions, experience and the
type of strainer used, service the air strainer.

POLYURETHANE SPONGE STRAINER

Every 5000 miles or 150 operating hours:

Remove and wash all of the parts. The strainer element
should be cleaned or replaced. If the element is cleaned, it
should be washed in a commercial solvent or a detergent
and water solution. The element should be saturated in clean
engine oil, then squeezed dry before replacing it in the
strainer. Be sure to replace the air strainer gasket if the
entire air strainer is removed from the compressor intake.

FIGURE 6 - PAPER AIR STRAINER DRY ELEMENT­PLEATED

FIGURE 5 - POLYURETHANE SPONGE STRAINER

FIGURE 7 - COMPRESSOR INTAKE ADAPTER

5

Every 6 months, 1800 operating hours or after each
50,000 miles:

Remove the discharge head fittings and inspect the
compressor discharge port and discharge line for excessive
carbon deposits. If excessive buildup is noted in either , the
discharge line must be cleaned or replaced and the
compressor checked more thoroughly, paying special
attention to the air induction system, oil supply and return
system, and proper cooling. If necessary , repair or replace
the compressor. Check for proper belt and pulley alignment
and belt tension. Adjust if necessary , paying special attention
not to over tighten the belt tension. Check for noisy
compressor operation, which could indicate a worn drive
gear coupling or a loose pulley. Adjust and/or replace as
necessary. Check all compressor mounting bolts and
retighten evenly if necessary . Check for leakage and proper
unloader mechanism operation. Replace if defective in any
way .

Every 24 months, 7200 operating hours or after each
200,000 miles:

Perform a thorough inspection as indicated below and
depending upon the results of this inspection or experience,
disassemble the compressor, clean and inspect all parts
thoroughly, rep air or replace all worn or damaged parts using
only genuine Bendix replacements or replace the
compressor with a genuine Bendix remanufactured unit.

Important: Should it be necessary to drain the engine cooling
system to prevent damage from freezing, the cylinder head
of the compressor must also be drained.

GENERAL SERVICE CHECKS

INSPECTION

It is of the utmost importance that the compressor receives
a clean supply of air. The air strainer must be properly
installed and kept clean. If the compressor intake is connected
to the engine air cleaner, supercharger, etc., these
connections must be properly installed and maintained.
Check the compressor mountings to be sure they are secure.
Check the drive for proper alignment, belt tension, etc.

Inspect the oil supply and return lines. Be sure these lines
are properly installed and that the compressor is getting the
proper supply of oil, and just as important, that the oil is
returning to the engine. Check the coolant lines to and from
the compressor and see that the cooling fins on the
crankcase are not clogged with dirt, grease, etc. Check the
unloader mechanism for proper and prompt operation.

OPERATING TESTS

Vehicles manufactured after the effective date of FMVSS
121, with the minimum required reservoir volume, must have
a compressor capable of raising air system pressure from

6

85-100 P.S.I. in 25 seconds or less. This test is performed
with the engine operating at maximum governed speed. The
vehicle manufacturer must certify this performance on new
vehicles with appropriate allowances for air systems with
greater than the minimum required reservoir volume.

AIR LEAKAGE TESTS

Leakage past the discharge valves can be detected by
removing the discharge line, applying shop air back through
the discharge port and listening for escaping air. Also, the
discharge valves and the unloader pistons can be checked
for leakage by building up the air system until the governor
cuts out, then stopping the engine. With the engine stopped,
listen for escaping air at the compressor intake. To pinpoint
leakage if noted, apply a small quantity of oil around the
unloader pistons. If there is no noticeable leakage at the
unloader pistons, the discharge valves may be leaking. If
the compressor does not function as described above, or
leakage is excessive, it is recommended that it be returned
to the nearest authorized Bendix Distributor for a factory
remanufactured compressor. If this is not possible, the
compressor can be repaired using genuine Bendix
replacement parts, in which case, the following information
should prove helpful.

REMOVING AND DISASSEMBLY

REMOVING

These instructions are general and are intended to be a
guide, in some cases additional preparations and precautions
are necessary . Chock the wheels of the vehicle and drain
the air pressure from all the reservoirs in the system. Drain
the engine cooling system and the cylinder head of the
compressor. Disconnect all air, water and oil lines leading
to and from the compressor. Remove the drive gear(s) or
pulley from the compressor crankshaft using a gear puller.
Inspect the pulley or gear and associated parts for visible
wear or damage. Since these parts are precision fitted, they
must be replaced if they are worn or damaged.

DISASSEMBLY

GENERAL

Remove road dirt and grease from the exterior of the
compressor with a cleaning solvent. Before the compressor
is disassembled, the following items should be marked to
show their relationship when the compressor is assembled.
Mark both the front and rear end cover in relation to the
crankcase. Mark the drive end of the crankshaft in relation
to the front end cover and the crankcase. Mark the cylinder
head in relation to the block and the block in relation to the
crankcase. Mark the base plate or base adapter in relation
to the crankcase.

A convenient method to indicate the above relationship is to
use a metal scribe to mark the parts with numbers or lines.
Do not use a marking method that can be wiped off or
obliterated during rebuilding, such as chalk. Remove all
compressor attachments such as governors, air strainers
or inlet fittings, discharge fittings and pipe plugs.

CYLINDER HEAD

Remove the six cylinder head cap screws (1) and tap the
head with a soft mallet to break the gasket seal. Remove
the inlet valve springs (2) and spring inserts (35) from the
head and inlet valves (3) from their guides in the block.
Remove inlet valve guides (4) from around the inlet valve
seats (34) on the block taking care not to damage seats.
Scrape off any gasket material (5) from the cylinder head
and block. Unscrew the discharge valve seats (6) from the
head and remove the discharge valves (7) and springs (8).
Inspect the discharge valve seats (2) for nicks, cracks, and
excessive wear and replace if necessary . The discharge valve
cap/nut stops (9) should be inspected for wear and replaced
if excessive peening has occurred. T o determine if excessive
peening has occurred, measure the discharge valve travel.
Discharge valve travel must not exceed .046 inches. If
discharge valve travel is excessive, replace the cap nut/stop
assembly , discharge valve and spring.

Discard the inlet valves (3) and springs (2), the discharge
valves (7), springs (8) and the discharge valve seats (6) if
defective.

CRANKCASE BASE PLA TE OR ADAPTER

Remove the cap screws securing the base plate or base
adapter. Tap with sof t mallet to break the gasket seal (11).
Scrape off any gasket material from crankcase and plate or
adapter.

CONNECTING ROD ASSEMBLIES

(Note: Before removing the connecting rods, mark each
connecting rod and its cap. Each connecting rod is matched
to its own cap for proper bearing fit, and these parts must
not be interchanged.) Remove the connecting rod bolts (13)
and bearing caps (14). Push the piston (15) with the
connecting rods (16) attached out the top of the cylinders of
the cylinder block. Replace the bearing caps (14) on their
respective connecting rods. Remove the piston rings from
the pistons. If the pistons are to be removed from the
connecting rods, remove the teflon plugs (36) and press the
wrist pins (37) from the pistons and connecting rods.

FLANGE

ADAPTER

CYLINDER BLOCK

16

26

24

27 22

26

1

8

7

6

18

20

19

18

19

15

21

17

14

25

20

37

23

12

CRANKSHAFT

13

9

CYLINDER HEAD

34

35

5

2

3

4

10

36

31

32

11

CRANKCASE

36

34

35

33

37

28

29

REAR COVER

30

REAR COVER

GASKET

FIGURE 8 - TU-FLO® 700 AIR COMPRESSOR (THRU DRIVE) EXPLODED VIEW

7

If the pistons are removed from the rod, inspect the bronze
wrist pin bushing. Press out and replace the bushing if it is
excessively worn. (See inspection of parts) Discard the piston
rings (18-20) and the connecting rod journal bearings (17).
Discard the wrist pin bushings (21) if they were removed.

CYLINDER BLOCK

Clean the carbon and dirt from the inlet and unloader
passages. Use shop air pressure to blow the carbon and
dirt deposits from the unloader passages.

CYLINDER BLOCK

If the compressor is fitted with an air strainer, inlet elbow or
governor remove the same.

Remove cap screws (23) securing cylinder block to the
crankcase; separate the crankcase and cylinder block and
scrape off any gasket material.

Remove the unloader spring (34), spring saddle (35), and
spring seat (36) from the inlet cavity of the crankcase, using
long nose pliers. With the use of shop air blow the unloader
plungers (37) and guides (33) out of the cylinder block.

The inlet valve seats can be removed if worn or damaged
and are being replaced. Unloader bore bushings should be
inspected but not removed unless they are damaged. If
bushings are to be replaced, they can be removed by running
a 1/8" pipe threaded rod and pulling the bushing straight up
and out. Do not use "easy out" for removing the bushings.

CRANKCASE

Remove the key (22) or keys from the crankshaft and any
burrs on the crankshaft where the key or keys were removed.

(Note: Through drive compressors may have a crankshaft
key at both ends.) Remove the four cap screws (23) securing
front or drive-end end cover or flange adapter. Remove the
end cover, t aking care not to damage the crankshaft oil seal
(27) or front main bearing (26), if any. Remove the o-ring (24)
from around the front end cover. Remove the four cap screws
(30) securing the rear end cover and remove the rear end
cover taking care not to damage the rear main bearing (29),
if any . Remove the o-ring (31) from around the end cover. If
the compressor has ball type main bearings, press the
crankshaft and ball bearings from the crankcase, then press
the ball bearings from the crankshaft.

OIL PASSAGES

Thoroughly clean all oil passages through the crankshaft,
crankcase, end covers, and base plate or base adapter.
Inspect the passages with a wire to be sure. Blow the
loosened foreign matter out with air pressure.

INSPECTION OF PARTS

CYLINDER HEAD BODY

Inspect the cylinder head for cracks or damage. Apply shop
air pressure to one of the coolant ports with all others
plugged, and check for leakage by applying a soap solution
to the exterior of the body. If leakage is detected, replace
the head.

END COVERS

Check for cracks and external damage. If the crankshaft
main bearings are installed in the end cover, check for
excessive wear and flat spots and replace them if necessary .
If the compressor has an oil seal in the end cover, it should
be removed by pressing it out of the end cover.

CRANKCASE

Check all crankcase surfaces for cracks and damage. On
compressors where ball bearing main bearings are used the
difference between the O.D. of the outer race and the I.D. Of
the crankcase hole should be .0000 in. to .0015 in. loose.
This is to maintain the correct press fit. The crankcase must
be replaced if the fit is too loose.

On compressors fitted with precision, sleeve main bearings,
the difference between the O.D. of the crankshaft journal
and the main bearing I.D. must not exceed .0065 in. If the
clearance is greater than .0065 in., the end cover or main
bearing must be replaced.

CLEANING OF PARTS

GENERAL

All parts should be cleaned in a good commercial grade
solvent and dried prior to inspection.

CYLINDER HEAD

Remove all the carbon deposits from the discharge cavities
and all the rust and scale from the cooling cavities of the
cylinder head body . Scrape all the foreign matter from the
body surfaces and use shop air pressure to blow the dirt
particles from all the cavities.

8

CYLINDER BLOCK

Check the unloader bore bushings to be sure they are not
worn, rusted, or damaged. If these bushings are to be
replaced, they can be removed by running a 1/8 in. pipe
thread tap into the bushing, and inserting a 1/8 in. pipe
threaded rod and pulling the bushing straight up and out. Do
not use an easy-out for removing these bushings. If the inlet
valve seats are worn or damaged, so they cannot be
reclaimed by facing, they should be replaced. Cylinder bores
should be checked with inside micrometers or calipers (see
Figure 9). Cylinder bores which are scored or out of round
by more than .001 in. or tapered more than .002 in. should

be rebored or honed oversize. Oversized pistons and piston
rings are available in .010 in., .020 in. and .030 in. oversizes.
Cylinder bores must be smooth, straight, and round.
Clearance between the cast iron pistons and cylinder bores
should be between .002 in. minimum and .004 in. maximum.

PISTON

RINGS

OIL RING

EXPANDER

PISTON

RING

.002
.004

STANDARD

PISTON

RING

.000
.006

RING

OIL RING

FIGURE 9 - MEASURING CYLINDER BORES

PISTONS

Check the pistons for scores, cracks, or enlarged ring
grooves; replace the pistons if any of these conditions are
found. Measure each piston with a micrometer in relation to
the cylinder bore diameter to be sure the diametral clearance
is between .002 in. minimum and .004 in. maximum.

Check the fit of the wrist pins to the pistons and connecting
rod bushings. The wrist pin should be a light press fit in the
piston. If the wrist pin is a loose fit, the piston and pin
assembly should be replaced. Check the fit of the wrist pin
in the connecting rod bushing by rocking the piston. This
clearance should not exceed .0007 in. Replace the wrist pin
bushings if excessive clearance is found. Wrist pin bushings
should be reamed to between .5314 in. and .5317 in. after
being pressed into the connecting rods.

Check the fit of the piston rings in the piston ring grooves.
Check the ring gap with the rings installed in the cylinder
bores. Refer to Figure 10 for correct gap and groove
clearances.

OIL RING

FIGURE 10 - CORRECT GROOVE CLEARANCE

END GAP

.002"
.010"

CRANKSHAFT

Check the crankshaft threads, keyways, tapered ends and
all machined and ground surfaces for wear, scores, or
damage. Standard crankshaf t journals are 1.1250 in.- 1.1242
in. in diameter. If the crankshaft journals are excessively
scored or worn or out of round and cannot be reground, the
crankshaft must be replaced. Connecting rod bearing inserts
are available in .010 in., .020 in. and .030 in. undersizes for
compressors with reground crankshafts. Main bearing
journals must be maintained so the ball bearings are a snug
fit or so that no more than .0065 in. clearance exists between
the precision sleeve main bearing and the main bearing
journals on the crankshaft. In crankshafts fitted with oil seal
rings, the oil seal ring groove or grooves must not be worn.
The ring groove walls must have a good finish and they must
be square. Check to be sure the oil passages are open
through the crankshaft.

CONNECTING ROD BEARINGS

Used bearing inserts must be replaced. Connecting rod caps
are not interchangeable. The locking slots of the connecting
rod and cap should be positioned adjacent to each other.
Clearance between the connecting journal and the
connecting rod bearing must not be less than .0003 in. or
more than .0021 in. after rebuilding.

9

REPAIRS

ASSEMBLY

DISCHARGE VAL VES, VAL VE STOPS AND
SEATS

If the discharge valve seats merely show signs of slight wear ,
they can be dressed by using a lapping stone, grinding
compound and grinding tool. Install the new discharge valve
springs and valves. Screw in the discharge valve seats.
Discharge valve travel should be between .030 in. to .046 in.

T o test for leakage by the discharge valves, apply 100 pounds
of air pressure through the cylinder head discharge port and
apply a soap solution to the discharge valves and seats. A
slight leakage in the form of soap bubbles is permissible. If
excessive leakage is found, leave the air pressure applied
and with the use of a fiber or hardwood dowel and a hammer,
tap the discharge valves off their seats several times. This
will help the valves to seat and should reduce the leakage.
With the air pressure still applied at the discharge port of
the cylinder head, check for leakage around the discharge
valve cap nut on the top of the cylinder head casting. No
leakage is permitted.

INLET VAL VES AND SEATS

Inlet valves and springs should be replaced, if the inlet valve
seats show signs of slight nicks or scratches. They can be
redressed with a fine piece of emery cloth or by lapping with
a lapping stone, grinding compound and grinding tool. If the
seats are damaged to the extent that they cannot be
reclaimed, they must be replaced. The dimension from the
top of the cylinder block to the inlet valve seat should not
exceed .1 13 in. nor be less than .101 in.

2

3

4

General Note: All torques specified in this manual are
assembly torques and can be expected to fall off after
assembly is accomplished. Do not retorque after initial
assembly torques fall.

T o convert inch pounds of torque to foot pounds of torque,
divide inch pounds by 12.

inch pounds ÷ 12 = foot pounds
T o convert foot pounds of torque to inch pounds of torque,

multiply foot pounds by 12.
foot pounds x 12 = inch pounds

INSTALLING THE CRANKSHAFT

Press new sleeve bearings in the end cover and crankcase.
Ensure that the slot in the bearings line up with the oil
passages in the end cover or crankcase. If you have a model
with no oil passage present in the crankcase, press the
sleeve bearing into the crankcase with the slot located 90
degrees from vertical.

Install the front thrust washer with the tang inserted in the
slot toward the flange. Insert the crankshaft and the rear
thrust washer with the tang toward the rear of the compressor .

Place the oil seal ring on the boss of the rear end cover and
install the end cover making sure not to pinch the seal ring.
Ensure the tang of the thrust washer is inserted in the slot
of the end cover. Fasten the end cover to the crankcase with
the four cover cap screws. Torque the cap screws to 175­225 inch pounds in a cross pattern. Note: For cast iron
flange adapters, torque the four 7/16 in. cap screws to 38­45 foot pounds. For die cast aluminum end covers, torque
the four 7/16 in. cap screws to 25-30 foot pounds. All end
covers using 5/16 in. cap screws or stud and nuts are torqued
to 15-18 foot pounds. For through drive compressors with a
cast iron end cover, torque the four 7/16 in. cap screws to
25-30 foot pounds.

8
6

DISCHARGE VALVE,

VAL VE STOP

AND SEAT

FIGURE 11 FIGURE 12

10

7

INLET VAL VE

AND SEA T

10

PISTONS AND CONNECTING RODS

If new wrist pin bushings are to be used, they should be
pressed into the connecting rods so that the oil hole in the
bushing lines up with the one in the rod. The new bushings
should then be reamed or honed to provide between .0001
in. (.00254 mm) and .0006 in. (.01524 mm) clearance on
the wrist pin. Position the connecting rod in the piston and
press in the wrist pin.

Pistons installed in compressors manufactured prior to
November, 1976, will have the wrist pin secured in the piston
by a lock wire extending through matching holes in wrist pin
and piston boss, anchored in a hole in the side wall of the
piston. If the original pistons are used the wrist pin must be
pressed in so the hole in the wrist pin aligns with that of the

piston and secure same by inserting the new lockwire
through the hole in piston and wrist pin and lock the wire by
snapping the short 90 section into the lockwire hole in the
bottom of the piston.

Compressors built after November, 1976, will have the wrist
pin secured by Teflon buttons in either end of the wrist pin,
allowing the wrist pin to float. The Teflon buttons pc. no.
292392 may be used with either new or old wrist pins. The
later design pistons have two rings above the wrist pin and
one below. Install the piston rings in the correct location
with the ring pipmarks up. Stagger the position of the ring
gaps. Prelubricate the piston, piston rings, wrist pins and
connecting rod.

CYLINDER BLOCK

Align gasket (12), crankcase and cylinder block and secure
with cap screws (23). T orque to 15-19 foot pounds.

UNLOADER

CYLINDER HEAD

Install the inlet valve springs in the cylinder head by applying
a turning motion to the spring after it is in the head. The
turning motion should dig the spring wire into the spring
seat in the bottom of the spring bore in the head. Should
this procedure fail after repeated attempts, use a very small
quantity of grease to hold them in place, just enough to
keep the springs from falling out. Place the cylinder head
gasket on the cylinder block. Carefully align the cylinder
head assembly on the block and install the cap screws,
tightening them evenly to a torque of 15-19 foot pounds.

BASE PLA TE OR BASE ADAPTER

Position the base plate or base adapter gasket on the
crankcase and install the base plate or base adapter as
marked before disassembly. Tighten the six cap screws
securing the cast iron base adapter evenly to a torque of 38­45 foot pounds, and 12-16 foot pounds for base plate or
aluminum cover.

A new unloader kit should used when rebuilding. (Figure

13). (Piece Number 279615). The unloader pistons in the kit
are prelubricated with a special lubricant piece number
239379 and need no additional lubrication. Install the unloader
pistons (28) in their bores being careful not to cut the
o-rings. Position the unloader plungers (37) in their guides
(38) and slip them in and over the tops of the pistons. Install
the unloader spring seat (36) in the cylinder block inlet cavity;
a small hole is drilled in the cylinder block for this purpose.
Position the saddle (35) between the unloader piston guides
(38), so its forks are centered on the guides. Install the
unloader spring (34), making sure it seats over the spring
seats both in the block and on the saddle. Position and
install the inlet valve guides (38), then drop the inlet valves in
their guides. The inlet valves should be a loose sliding fit in
the guides.

36

38

34

37

28

TESTING REBUILT COMPRESSOR

In order to properly test a compressor under operating
conditions, a test rack for correct mounting, cooling,
lubricating, and driving the compressor is necessary . Such
tests are not compulsory if the unit has been carefully rebuilt
by an experienced person. A compressor efficiency or build­up test can be run which is not too difficult. An engine
lubricated compressor must be connected to an oil supply
line of at least 15 P.S.I. pressure during the test and an oil
return line must be installed to keep the crankcase drained.

Connect to the compressor discharge port, a reservoir with
a volume of 1500 cubic inches, including the volume of
connecting line. With the compressor operating at 2100
R.P .M., the time required to raise the reservoir(s) pressure
from 85 P.S.I. to 100 P.S.I. should not exceed 7 seconds.
During this test, the compressor should be checked for
gasket leakage and noisy operation, as well as unloader
operation and leakage.

INSPECTION OF REBUILT UNIT

Check to be sure that covers, plugs, or masking tape are
used to protect all ports if compressor is not to be installed
immediately . Fit the end of all crankshaf ts with keys, nut s,
and cotter pins as required and then protect the ends against
damage by wrapping with masking tape or friction tape. The
open bottom of a vertical engine lubricated compressors
should be protected against the entrance of dirt during
handling or storage, by installing a temporary cover over the
base.

35

FIGURE 13 - UNLOADER MECHANISM

11