oil capacity OPEL 1900 1973 Service Manual

IoC-91973 OPEL SERVICE MANUAL
Figure OC-5 Brake Master Cylinder
I
Figure OC-6 Tire Rotation Methods
when the clutch pedal has in excess of 1
l/4 inch fr&
travel. See Figure OC-7.
Rear Axle
Change lubricant every
12,ooO miies when vehicle is
used for pulling a trailer.
Cooling SystemCheck at 12-month or
12,000~mile intervals, wash
radiator cap and filler neck with clean water, pres-
sure test system and radiator cap for proper pressure
holding capacity (tighten hose clamps and inspect
condition of all cooling and heater hoses). Replace
hoses every 24 months or 24,000 ,miles or earlier :if
checked, swollen or otherwise deteriorated.
Also each 12 months or
12,ooO miles, clean exteribr
of radiator core. Every 24 months or
24,OCO miles,Floor-Pan
-Clutch Pedal
Figure OC-7 GT Clutch Lash
drain, flush, and refill the cooline svstem with a new
coolant so&ion of permanent
6~; anti-freeze and
water for protection-of -20°F.
D-6 NOT REMOVE
RADIATOR CAP WHEN SOLUTION IS HOT
AND UNDER PRESSURE.
Wheel BearingsClean and repack front wheel bearings with a lubri-
cant as specified on the lubrication chart, Figure
oc-1.
Automatic Transmission FluidUnder normal driving conditions, change the trans-
mission fluid every 24,000 miles. Under unusual con-
ditions such as constant driving in heavy city traffic
during hot weather, trailer pulling, etc., this service
should be performed at
12,COO mile intervals.
General Motors DEXRON Automatic Transmis-
sion Fluid, which has been especially formulated and
tested for use in your automatic transmission, is
recommended. Other automatic transmission fluids
identified with the mark DEXRON are also recom-
mended.
Check the fluid level at each engine oil change
period. To make an accurate fluid level check:
1. Drive car several miles, making frequent starts and
stops, to bring transmission up to normal operating
temperature (approximately
180-190’F.)2. Park car on a level surface.
3. Place selector lever in “Park” and leave engine
running.

lC- 261973 OPEL SERVICE MANUAL /
SPECIFICATIONSIGNITION COIL
Ignition Coil Number
.,.:.................................................................................................K12 V
Ignition Coil Current Draw, Amperes at 12.5 Volts
EngineStopped
...........:.........................._............................................................................3.8Engine Idling
....................................................................................................................2.3
DISTRIBUTORDistributor TypeNumber:
..................................................................................................JFU4
Total Advance (Centrifugal and Vacuum), Engine Degrees at 3600 R.P.M.
EngineRPM
..................................................................................................................29-37Centrifugal Advance, Engine Degrees and RPM
StartAdvance,atRPM
........................................................................................lOOO-1200MediumAdvance,DegreesatRPM
..............................................................7.5-15at1400Maximum Advance, Dkgrees at RPM
..........................................................28-32 at 3600
Vacuum Advance, Engine Degrees and
In. of Vacuum
Start Advance, at In. of Vacuum
................................................................-5 at 2.9-4.1 In.
Maximum Advance, Degrees at In. of Vacuum
........................................l-5 at 4.5-5.0 In.
VacuumRetard,EngineDegreesatClosedThrottle
............................................................-5CondenserCapacityinMicroFarads
...............................................................................15-.20Breaker Spring Tension in Ounces
..............................................................................14 to 19
Breaker Point Gap in Inches
..............................................................................................,016Dwell angle in Engine Degrees
....................................................................................50 + 3
Firing Order
....................................................................................................................l-32-2
SparkPlug or CoilCable,Max.Resistancti in Ohms
..................................................10,ooO
SPARK PLUGSMake and Model
-Production................I....................................................................AC42FS
Make and Model
- Replacement...................................................................................AC42FS
Ifcarbonfouling
occurs,use.....................................................................................AC43FS
SparkPlugTorqueinLb:Ft.
............................................................................................22-29Spark Plug Gap in Inches
...........................................................................................028-.03 1

48. 221973 OPEL SERVICE MANUAL
9. Position
case assembly and outer races in the car-
rier. Use a soft-faced hammer to drive the case into
the carrier until the side bearing outer races bottom
in their bores.
10. Install side bearing caps in their original location
and torque the bolts to 33
lb.ft.IN. LB. TORQUL
11. Rotate case assembly several times to seat the
bearings. Check backlash and preload using a torque
wrench on a ring gear attaching bolt. See Figure 4B-
35. Torque required to turn case should be 20 to 30
Ib.in. for new bearings or 10 to 20 lb.in., for used
bearings. If torque is not correct, it will be necessary
to r&him the side bearings.
12. Insta!l torque tube assembly.
13. Install axle shafts.Figure 48.35 Checking Side Bearing
Preload
SPECIFICATIONS
DIFFERENTIAL SPECIFICATIONS
General SpecificationsRear Axle Type
.,,...,,,...,,_...._..,,...,,,...,,,....,,.,...,,.,,...,,..,,,........................ Semi-Floating Hypoid
Rear Axle Oil Capacity
..____,,...,,,...,.,..,............,,..,,..,,................................................. 2 l/2 7’.Ring and Pinion Gear Set Type
. . . . . . . . . . . . . . . . . .._................................................................Hypold
Axle Ratios

6A- 28 1973 OPEL SERVICE MANUAL
Part
ConnectingRod Bolts..........................................................
Crankshaft Main Bearing Bolts
..........................................
FlywheeltoCrankshaft AttachingBolts..........................
Cylinder Head Attaching Bolts....Cold 72 -Warm 58
Camshaft Sprocket Attaching Bolts................................
Generator Bracket to Cylinder Block
Attaching Bolts ..................................................................
Generator Bracket to Timing Case Attaching Bolts
....
Crankshaft Pulley Attaching Bolts ....................................
Rocker Arm Stud in Cylinder Head ..................................
Spark Plugs ........................................................................\
....
Clutch Housing to Cylinder Block Attaching Bolts
......
Timing Case to Cylinder Block AttachingBolts ............
Water Pump to Timing Case AttachingBolts................
Engine Support to Cylinder Block Attaching Bolts
......
Rear Engine Suspension to Transmission Rear Bearing Retainer Bolts ....................................................
Transmission to Clutch Housing Attaching Bolts
........
Starter to ClutchHousing AttachingBolts....................
Support to Starter Attaching Nut
....................................
Intake and Exhaust Manifold to Cylinder Head Attaching Bolts ..................................................................
Unless Otherwise Noted:
10
@i Bolt (15 MM Hall.....................................................................- -
36
72
43
18
;i
72
29
30
36
14
11
40
22
29
40
4
33 ............30
8 MM Bolt (13 MM Head)........................................................................\
........................................................................\
........................................15
6 MM Bolt (10 MM Head)
30 Lb.In.
Torque
Lb.Ft.
GENERAL SPECIFICATIONS
Type - No. of Cylinders
Valve Arrangement........................................................................\
........................................................................\
......................................................I;nlinzai
Bore and Stroke Piston Displacement Cu. In.
........
3.66 x1:;:;
Compression Ratio......................................................................................\
........................................................................\
........................................................................\
........................................
\fô\
²…..............7.6:1Octane Requirement........................................................................\
..........
Firing Order........................................................................\
........................
Regular - Lo;-?::
....................Cylinder Block Material....... ...............................................................................\
..............................................Cast Iron
Crankshaft Bearings Number and Type 5 Removable Steel Backed
In-Metal Babbitts
Bearing Which Takes End Thrust
........................................................................\
...................5
Connecting Rod Bearing Material
........................................................................\
..................
Steel Backed Tri-Metal Babbttts
Piston Material and Surface Aluminum Alloy, Lead Coated
Piston Pin Offset
........................................................................\
............,031 In. to the RightCompression Rings Material and Surface Treatment
No.
1....... ........... ............... ........ ............. ................Chrome-plated, Cast Iron
- Rectangular
No. 2
........................................................................\
..............................Cast Iron - Tapered
Oil Ring
........................................................................\
..................Chrome-plated, Cast Ir?n
Location of All Piston Rings
........................................................................\
Above Ptston Pm
Camshaft Material
........................................................................\
....................Alloy Cast Iron
Camshaft Drive........................................................................\
........................................Chajn
Number and Type of Camshaft Bearings 4 Steel-Backed Babbttt
Valve Lifter Type
..............................................................................................\
..........................................~..........Hydraulic
Oiling System Tvoe........................................................................\
Circulatmg High Pressure
Oil
&ppiied to: - .
Bearing Surfaces, Crankshaft, Camshaft and Connecting Rods............................Pressure
Piston, Pins
........................................................................\
............................................Vapor
Cvlinder Walls........................................................................\
..........................Nozzle Spray
Rocker Arms _,,,..,,....,._..___.,,..,,..............,,,,...,.......,..,,,.,.,,.....\
....,,...,.,.................~...... Pressure
Oil Reservoir Capacity
- Quarts .,,,...,,__.,,..,..,,..,...,..,,,...,,..............,,,... 3 l/4 With Dry Fdter
Oil Filter
- Type ,,....,__.,,...,....,....,,..,,,..,,...........,........................\
............ Throw Away Element

ENGINE MECHANICAL AND MOUNTS6A- 29
Cooling System - Type ,._...___..___..___........................... Liquid Cooling With Circulating Pump
Filler Cap Type
- Pressure _,._.,,._.,,...,,.........,..,.....,.,.................,,......................... 13.2-15.2 PSI
Water Temperature Control
._,..__,,._.,,__.,,...,.,.,,.,,.,,.,...............,,...,,,... Thermostat and Bypass
Thermostat Open At
._,,.,,.......,__.,.........,,...,...,,..,.,,.,,...................................................... 189 F.
Cooling System Capacity
. . . . . . . . . . . . .._...__..............,,.,,.,,..,...................................,,................6 Qts.
Fan Drive
.,,...,,,....,,.,..,..,,........,..,,..,,,.............,..,,.,..,,.................,,............... Water Pump Shaft
ENGINE DIMENSIONS AND FITS
Cylinder, Crankcase, Pistons, Cylinder Head, Valves
Cyg;te; Bore Limits for Standard Size Pistons:3.659-3.660 In.
Size 23.661-3.663 In.Size 3
3.664-3.668 In.Cylindey Bore Limits for Oversize Pistons,
.02 In.Oversm
. .._............,..,,...,................................,,.,,.,,.........................................3.679-3.681 In.
Max.PermissibleCylinderBoreOut-of-Roundness
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..~.OOO5In.Max.Permissible Cylinder Bore Taper
,.., ,.,, ,.,._,__. ,_, ,.. .__... ..__. ,__. .____. ..__. .._..0005In.Piston Clearance, Nominal (on skirt bottom)
_..__,,_.,.___.__.._...........,.......................... .0014 In.No. 1 Compression Ring Side Clearance in
Piston Groove
,...,,,.,,,.,,...,__..........,,..,,...,,...,..,.,,.,,..,,..,,..,,..................,,,..,,,..., .0024-.0034 In.
No. 2 Compression Ring Side Clearance in
Piston Groove
_..,,..,,,..,,..,,..,,....,.......,...,,,.,.,,,..,..,..,,..,,..,,,..,,,.,,,..,,,...,,,..,,,,..., .0013-.OO24 In.
Oil Control Ring Side Clearance in Piston
Groove
__..__..._..,,,..,...,,,..,....,..,,..,.........,..,,...,,.,,.,,..,..,,..,,...,,...,,,..,,,..,,,...,,..... .0013-X024 In.
Piston Ring Gap:
No. 1 Compression Ring
..,,.,,,..,,,..,,..,,,.,,.,,,..,......,,.,..............,......................... .014-,022 In.
No. 2 Compression Ring
_..___..__.,,..,,..,,,..,.,,,..,,.,,....................,......................... .014-,022 In.
Oil Control Ring
,...,,...,___.___.._..................,,,..,..,,..,,.,,,..,,,.,,..,,,..,,,...,,,,..,,,...,.... ,015.,055 In.
Piston Pin in Connecting Rod
..____.___..._,,__.,,,,,..,,.,,..,.................,,............................... Press Fit
IntakeExhaust
Valve Spring Pressure
Valve Closed
_______........___..,,,,,,............1.57 In. at 93 Lbs.1.36 In. at 97
Lbs.
ValveOpen. . . . . . . . . . . . . . .1.18 In. at 182 Lbs..96 In. at 180
Lbs.
Valve Stem Diameters
Standard
Size. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..3538-.3543 In..3524-.3528 In.,003 In. Oversize
____.....__.._..,,,,,,.........3567-.3572 In..3553-.3559 In..0059 In.
Oversze .__......_______...............3597-.3602 In..3583-.3588 In.
.O 1 18 In. Oversize
_._...._._____...............3656-.3661 In..3642-.3647 In.
Valve Length, Nominal
..___.............4.843 In.4.92 In.
Valve Head Diameter
___.......____...,,,........1.574 In.1.34 In.Valve Guide Bores in Cylinder Head (Intake and Exhaust)
Standard Size
,,...,,...,,..,,..,,,..,,....................................,..,,...,,.,,,,..,,,,..,,...,,,,.., .3553-.3562 In.003 in Oversjze
.,..__,,._.,__..___....,,...,,..,,...,,,,,,.,,.,,..,................,.....,................. .3582-.3592 In.
,006 in Overslze
..,...,,..,,.......................................,.........................................3615-.3622 In.
.0118 in Oversize ,._.,,..,............,,...,,........................................,,.................... .3671-.3681 In.
Valve Stem Clearance
Intake .
.._........___..___.....,............,...,,..........................................,,...................... .OOl-.0029 In.
Exhaust
._.,,........,,...,,..,,...........,,...,................,..,,..,,................,,.....,.,........................ 0039 In.
Max. Permissible Head to Stem Runout
Intake
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..OO16In.Exhaust
.,...........,,...,...,.,,...........,,...,....,....,.,,,..,,.,,,........................................,.......... .0019 In.

6G- 68 1973 OPEL SERVICE MANUAL
SPECIFICATIONS
TUNE-UP SPECIFICATIONS AND ADJUSTMENTS
Voltage Regulator
Voltage Regulator Setting in Volts at2500 Engine RPM. . . . . . . . . . . . . . . . . . . . . .14+.5
Ignition Coil
Ignition Coil Current Draw, Amperes at 12.5 Volts
Engine Stopped
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . \
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . \
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . \
. . . . . .3.8
EngineIdling. . . . . . . . . . . . . . . . . .._.....................................................................\
........................... 2.3
Total Advance (Centrifugal and Vacuum), Engine Degrees at 3600 Engine \
RPM......29-38
Centrifugal Advance, Engine Degrees and RPM
Start Advance, atRPM
........................................................................\
................ 1000-1200
Medium Advance, Degrees at RPM..............................................................7.5-15 at 1400
Maximum Advance, Degrees at RPM
..........................................................28-32 at 3600
Vacuum Advance, Engine Degrees and In. of Vacuum Start Advance..
........................................................................\
.................-5at2.9-4.1 In.
Maximum Advance..........................................................................\
........1-5at4.5-5.0In.
Vacuum Retard, Engine Degrees at Closed Throttle............................................................-5
Condenser Capacity in
MicroFarads........................................................................\
.......23-.32
Breaker Spring Tension in Ounces........................................................................\
......14 to 19
Breaker Point Gap in Inches
........................................................................\
......................,016
Dwell AngleinEngine Degrees........................................................................\
.......... 50+3
Firing
Order........................................................................\
............................................l-3-4-2
Spark Plug or Coil Cable,Max.Resistance in Ohms
..................................................
10,000
Spark Plugs
Make and Model Production........................................................................\
............AC42FS
Make andModel
-Replacement........................................................................\
..........AC42FS
If carbon fouling occurs, use
........................................................................\
............AC43FS
Spark Plug Torque in
Lb.Ft.........................................................................\
.........................30
Spark Plug Gap in Inches........................................................................\
..........................,030
Valve Lifter Adjustment
One full turn (clockwise) after zero clearance is obtained - refer to Valve Adjustment
Procedure
Ignition Timing
Align timing marks with distributor retard hose disconnected and plugged\

712.501973 OPEL SERVICE MANUAL
3. Detent pressure regulator valve.
4. 1 - 2 Accumulator valve.
5. Governor.
B. Selector valves (manually and hydraulically con-
trolled).
I. Manual valve.
2. Detent valve.
3. 1
- 2 Shift valve.
4. 2
- 3 Shift valve.
5. 3
- 2 Downshift control valve.
6. Manual low and reverse control valve.
7. Boost control valve.
C. Timing Valves.
1. Low speed downshift timing valve.
2. High speed downshift timing valve.
3. Second clutch orifice valve.
D. Accumulators.
1. 1
- 2 Accumulator.
2. Low servo piston.
Main Pressure Regulator ValveOil pressure from the pump is delivered to the “line”
port of the main regulator valve. See Figure
7C-30.The port is connected through a damping orifice, to
the regulator port at the end of the regulator valve.
As the pressure in this port increases, it moves the
valve against the spring force until the second spool
of the. valve just opens to the “line” port. This per-
mits the pump pressure to be by- passed into the
pump suction passage. Therefore, the valve will regu-
late at
a’ fixed minimum pressure as determined by
the spring force, and all excess pump delivery will be
by-passed back into the pump suction passage.
In moving from the “bottomed” to the regulating
position, the valve also opens line pressure to the
converter feed passage. This oil is directed to and
through the
cow&x, through the oil cooler, to the
gear box lubrication system, then back to the sump.
In order to provide the required capacity in the band
and clutches, it is desirable to have a variable line
pressure that will increase with engine torque. This
PRESSURE’REGULATORY7c30Figure 7C-30 Pressure Regulator Valve
is accomplished by introducing a “modulator” pres-
sure on the end of the boost valve. The force of the
boost valve acts against the end of the regulator valve
and increases the line pressure above the base pres-
sure as established by the spring force. By introduc-
ing line pressure to the stepped area between the
spools of the boost valve, an additional pressure in-
crease over and above that described above is ob-
tained.
The regulated line pressure is then fed to:
Manual valve.
Modulator valve
Detent pressure regulator valve
Modulator Valve and Vacuum ModulatorLine pressure is directed to the second port of the
modulator valve. See Figure
7C-31. This pressure
passes between the spools of the valve and into the
modulator port. The modulator port is connected to
the regulating port at the end of the valve through a
damping orifice. As the pressure in the regulating
port incieases, it moves the valve outward against
the spring force of the modulator assembly until the
end spool just closes the line port. If excess pressure
has built up in the regulating port the valve will
continue to move till the second spool just opens to
the exhaust port. In other words, the valve tends to
regulate between the line and exhaust ports.
Even though the modulator spring force may be con-
stant, thereby causing the modulator valve to regu-
late at a fixed pressure, the pressure requirements

AUTOMATIC TRANSMISSION 7C-135
becomes necessary to check the fluid level, the trans-
mission may be checked at room temperature (70
degrees F.) as follows:
1. With manual control lever in Park position start
engine. DO NOT RACE ENGINE. Move manual
control lever through each range.
2. lmmediately check fluid level with selector lever
in Park, engine running, and vehicle on LEVEL sur-
face.At this point, when a reading is made, fluid level on
the dipstick should be I/4” below the “ADD” mark.
3. If additional fluid is required add fluid to bring
level to
l/4” below the “ADD” mark on the dip-
stick.If transmission fluid level is correctly established at
70 degrees F. it will appear at the “FULL” mark on
the dipstick when the transmission reaches normal
operating temperature (180 degrees F.) The fluid
level is set
l/4” below the “ADD” mark on the
dipstick to allow for expansion of the fluid which
occurs as transmission temperatures rise to normal
operating temperature of 180 degrees F.
Do not overfill, as foaming and loss of fluid through
the vent pipe might occur as fluid heats up. If fluid
is too low especially when cold, complete loss
of’drive may result which can cause transmission fail-
ure.
2.Draining oilpan and rep/a&g strainer assembly.
(a) Raise car on hoist or p/ace OnJxk stands, and
provide container to collect draining fluid.
(b) Remove oil pan and gasket. Discard gasket.
(c) Drain fluid from oil pan. Clean pan with solvent
and dry thoroughly with clean compressed air.
(d) Remove strainer assembly, strainer gasket and
discard.
(e) Install new oil strainer gasket. Install new strainer
assembly.
(f) Install new gasket on oil pan and install pan.
Tighten attaching bolts to 7-10 lb. ft.
(g) Lower car and add approximately three (3) pints
of transmission fluid through filler tube.
(h) With manual control lever in Park position, start
engine. DO NOT RACE ENGINE. Move manual
control lever through each range.
(i) Immediately check fluid level with selector leverin Park, engine running, and vehicle on LEVEL
sur-
face.(i) Add additional fluid to bring level to
l/4” below
the “ADD” mark on the dipstick. Do not overfill.
3.Adding Fluid to Fill Dry Transmission and Con-
verter Assembly
The fluid capacity of the Opel Three Speed Auto-
matic transmission and converter assembly is ap-
proximately IO-l/2 pints, but correct level is
determined by the mark on the dipstick rather than
by amount added. In cases of transmission overhaul,
when a complete fill is required, including a new
converter proceed as follows:
(a) Add approximately 10-l/2 pints of transmission
fluid through tiller tube.
The converter should be replaced on any major fail-
ure, such as a clutch or gearset, and an excessive
amount of foreign material is indicated in the pan. If
installation of a new converter is not required add
approximately five (5) pints of transmission fluid.
(b) With manual control lever in Park position start
engine and run at 1000 RPM. DO NOT RACE EN-
GINE. Move manual control lever through each
range.
(c) Immediately check fluid level with selector lever
in Park, engine running, and vehicle on LEVEL
sur-
face.(d) Add additional fluid to bring level to
l/4” below
the “ADD” mark on the dipstick. Do not overfill.
Opel Three Speed Automatic Transmission Towing
Instructions
If an Opel equipped with an automatic transmission
must be towed, the following precautions must be
observed:
The car may be towed safely on its rear wheels with
the shift lever in neutral position at speeds of 35 miles
per hour or less under most conditions.
However, the drive shaft must be disconnected or the
car towed on its front wheels if:
a. Tow speeds in excess of 35 mph are necessary.
b. Car must be towed for extended distances (over 50
miles).
c. Transmission is not operating properly.
If car is towed on its front wheels, the steering wheel

9B-30 1973 OPEL SERVICE MANUAL
refrigerant penetrates to every nook and cranny of
the unit.
Among the many desirable properties of R-12, is its
stability under operating conditions. However, while
more stable than the other refrigerants under the
same conditions, it, too, can be caused to form harm-
ful acids which will eventually fail the system.OilOil is the most complex of all of the organic chemi-
cals. Its stability in a refrigerating system is depend-
ent upon the source of crude oil and its method of
refining. A good refrigerating oil must be free of
sludge and gum-forming substances and free of
harmful impurities, such as sulphur. It must also be
stabilized to resist oxidation and must have a high
degree of resistance to carbonization.
The chemical properties of the lubricating oil form
another very important consideration in the chemi-
cal stability within the system. Like the refrigerant,
it travels to every nook and cranny of the unit.
The factory obtains the finest oils which have been
refined from the most desirable
crudes. It is reproc-
essed at the factory before it is charged into a system
or poured into a container for resale. Its
voscosityand flash point are checked and it is forced through
many sheets of filtering paper.
Even the containers in which it is poured for resale
are processed. As you recive it for field service it is
the cleanest, dry&, and purest oil that is humanly
possible to make. Leaving the container uncapped
even for a few minutes allows the oil to absorb mois-
ture from the air. Many system failures have been
caused by chemical reactions which were started by
servicemen adding contaminated oil.
Desiccants (Dehydrating Agent)Over the years the industry has spent hundreds of
thousands of dollars in finding and developing
chemical substances which are suitable for use in
refrigerating systems. An ideal desiccant must have
the following characteristics:
I. High capacity.
2. High eficiency.
3. Low tendency to powder.
4. Absorb moisture without reacting chemically with
it.5. Allow refrigerant to flow through it with mini-
mum restriction.
6. Retain moisture at high temperature.This has been a difficult combination to find. While
some desiccants excel in several of the desirable char-
acteristics, they are unsatisfactor:y in others.
Activated Silica Alumina, used in current
receiver-dehydrators, is a most satisfactory desiccant. How-
ever, its ability to retain moisture is affected by its
temperature. As the temperature increases, its ability
decreases. This means that moisture which is re-
tained at a lower temperature may be put back into
the system at a higher temperature.
MAINTAINING CHEMICAL STABILITY IN THE
REFRIGERATION SYSTEMThe metal internal parts of the refrigeration system
and the refrigerant and oil contained in the system
are designed to remain in a state of chemical stability
as long as pure R-12 plus refrigeration oil is used in
the system. However, when abnormal amounts of
foreign materials, such as dirt, air or moisture are
allowed to enter the system, the chemical stability
may be upset (Fig. 9B-24).
Figure
98.24 System Contaminants
When accelerated by heat, these contaminants may
form acids and sludge and eventually cause the
breakdown of components within the system. In ad-
dition, contaminants may affect the temperature
pressure relationship of R-12, resulting in improper
operating temperature and pressures and decreased
efficiency
OF the system.
The following general practices should be observed
to maintain chemical stability in the system:
Whenever it becomes necessary to disconnect a re-
frigerant or gauge line, it should be immediately
capped. Capping the tubing will also prevent dirt and
foreign matter from entering.
Tools should be kept clean and dry. This also in-
cludes the gauge set and replacement parts.

REFRIGERANT COMPONENTS ALL MODELS9B- 31
When adding oil, the container should be exception-
ally clean and dry due to the fact that the refrigera-
tion oil in the container is as moisture-free as it is
possible to make it. Therefore, it will quickly absorb
any moisture with which it comes in contact. For this
same reason the oil container should not be opened
until ready for use and it should be capped immedi-
ately afte;r use.
When it is necessary to open a system, have every-
thing you will need ready and handy so that as little
time as possible will be required to perform the oper-
ation. Don’t leave the system open any longer than
is necessary.
Finally, after the operation has been completed and
the system sealed again, air and moisture should be
evacuated from the system before recharging.
THE PRIMARY CAUSES OF SYSTEM FAILURES
LeaksA shortage of refrigerant causes oil to be trapped in
the evaporator. Oil may be lost with the refrigerant
at point of leakage. Both of these can cause compres-
sor seizure.
Oil circulates in the system with the refrigerant; in
solution with the liquid and in globules with the
vapor. It leaves the compressor by the action of the
pistons and mixes with the refrigerant liquid in the
condenser. The oil then enters the evaporator with
the liquid and, with the evaporator properly flooded,
is returned to the compressor through the low pres-
sure line. Some of the oil returns as globules in the
vapor, but more important, it is swept as a liquid
along the walls of the tubing by the velocity of the
vapor. If the evaporator is starved, the oil cannot
return in sut?icient quantities to keep the compressor
properly lubricated.
High Temperature and PressureAn increase in temperature causes an increase in
pressure. This accelerates chemical instability due to
existing contaminants in the system, and initiates
chemical instability in clean systems. Other results
are brittle hoses,
“0” ring gaskets, and valve dia-
phragms with possible decomposition, broken com-
pressor discharge reeds, and seized compressor
bearings.
A fundamental law of nature accounts for the fact
that when a substance, such as a refrigerant, is in-
creased in temperature, its pressure is also increased.
Any chemical reactions caused by contaminants al-
ready in the system are greatly accelerated as the
temperature increases. A 15 degree rise in tempera-
ture doubles the chemical action. Even in a goodclean system, heat alone can start a chain of harmful
chemical reactions.
While temperature alone can cause the synthetic rub-
ber parts to become brittle and possibly to decom-
pose, the increased pressure can cause them to
rupture or blow.
As the temperature and pressure increases the stress
and strain on the compressor discharge reeds also
increases. This can result in broken reeds. Due to the
effect of the contaminants caused by high tempera-
ture and pressure, compressor bearings can be
caused to seize.
High temperature and pressure are also caused by air
in the system.
Air in the SYstemAir results from a discharged system or careless ser-
vicing procedures. This reduces system capacity and
efficiency and causes oxidation of oil into gum and
varnish.
When a leak causes the system to become dis-
charged, the resulting vacuum within the system will
cause air to be drawn in. Air in the system is a
non-condensable gas and will build up in the con-
denser as it would in an air compressor tank. The
resultant heat produced will contribute to the condi-
tions discussed previously.
Many systems are contaminated and also reduced in
capacity and efficiency by servicemen who either do
not know or are careless regarding proper servicing
procedures.
Too frequently, systems which have been open to the
atmosphere during service operations have not been
properly purged or evacuated. Air is also introduced
into the system by unpurged gauge and charging
lines. Remember that any air in the system is too
much air.
Poor ConnectionsHose clamp type fittings must be properly made.
Hoses should be installed over the sealing flanges and
with the end of the hose at the stop flange. The hose
should never extend beyond the stop flange. Locate
the clamp properly and torque as recommended. Be
especially careful that the sealing flanges are not
nicked or scored or a future leak will result.
When compression fittings are used, over tightening
can cause physical damage to the “0” ring gasket
and will result in leaks. The use of torque and back-
ing wrenches is highly recommended. When making
a connection with compression fittings, the gaskets
should always be first placed over the tube before