1973 OPEL GT-R brake fluid

LUBRICATION AND MAINTENANCE OC-5LUBRICATION AND MAINTENANCE
LOEngine Oil ,current “ISCOI-ifVl SE’
-u9 Lubriplate’,9F Hvdraulic Brake Fluid -Delco supreme NO. 11’
CAPAClTlESOPEL 1900Coding SystemMANTA GT
,OW,6 6
UU
3oclFigure OC-1 1973 Lubrication Chart

LUBRICATION AND MAINTENANCE OC-7SERVICESLUBE AND GENERAL MAINTENANCE
Vehicle operation under conditions such as heavy
dust, continuous short trips, use of other than un-
leaded or low lead fuels or pulling trailers, is not
considered normal use and therefore more frequent
maintenance will be required. Such additional
maintenance requirements are included where appli-
cable.
Engine OilChange each 4 months or
3,COO miles, whichever
occurs first, or each 2 months or
3,ooO miles when
the vehicle is operated under the following condi-
tions: (a) driving in dusty conditions, (b) trailer pull-
ing, (c) extensive idling or (d) short-trip operation at
freezing temperatures (with engine not thoroughly
warmed-up).Engine oils have a definite effect on ease of starting,
oil economy, combustion chamber deposits and en-
gine wear. It is recommended that a” oil which,
according to the label on the can is; (1) intended for
service SE and (2) passes car makers’ tests be used.
Oils confotming to these types contain detergent ad-
ditives. -
Select the proper oil viscosity from Figure OC-3.
Engine Oil FilterReplace at the first oil change and every other oil
change thereafter using Part No. 7965051 or equiva-
lent.
ChassisLubricate transmission shift linkage, hood latch and
parking brake cable guides and linkage.
Fluid LevelsCheck level of fluid in brake master cylinder, battery,
engine, axle, transmission and windshield washer.
Engine coolant also should be checked for proper
level and for corrosion and freeze protection to at
least -20°F or to the lowest temperature expected
during the period of vehicle operation. Proper engine
coolant also provides corrosion protection.
Any significant fluid loss in any of these systems or
units could mea” that a malfunction is developing
and corrective action should be taken immediately.
A low fluid level in the brake master cylinder front
reservoir could also be a” indtcator that the disc
brake pads need replacing.
The engine oil should be maintained at proper level.
The best time to check it is before operating the
engine or as the last step in a fuel stop. THIS WILL
ALLOW THE NORMAL OIL ACCUMULA-
TION IN THE ENGINE TO DRAIN BACK IN
the crankcase. To check the level, remove the oil
gauge rod (dipstick), wipe it clean, and reinsert it for
a” accurate reading. The oil level should be main-
tained in the safety margin, neither going above the
“FULL” mark “or below the “ADD OIL” mark.
See Figure OC-4.
DIP STICK MUST BE
INSERTED TO STOP
---L- -FULL+, 1 OT. ,-ADD
OIL
Figure OC-4 Engine Oil Dipstick
All models are equipped with tandem brake cylin-
ders. Maintain fluid level between MIN and MAX
marks on reservoir. See Figure OC-5. When adding
fluid use Delco Supreme No. 11 or equivalent.
TiresTo equalize wear, rotate tires as illustrated in Figure
OC-6.Adjust clutch when necessary as indicated by the
clutch warning lamp on Opel 1900 and Manta or

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.

LUBRICATION AND MAINTENANCE OC-9
4. Remove dipstick and wipe clean.
5. Reinsert dipstick untip cap seats.
6. Remove dipstick and note reading.
If fluid level is at, or below the ADD mark, add
sufficient fluid to rais the level to the FULL mark.
One pint raises the level from ADD to FULL. Do
not overfill.
3OC8Figure OC-8 Automatic Transmission Dipstick
SAFETY MAINTENANCE
Brake Lines and HosesCheck for proper attachment, leaks, cracks, chafing,
deterioration, etc. Any questionable parts noted
should be replaced or repaired immediately. When
abrasion or wear is evident on lines or hoses, the
cause must be corrected.
Tires and WheelsCheck tires for excessive wear, nails, glass, cuts or
other damage. Make certain wheels are not bent or
cracked and wheel nuts are tight. Uneven or abnor-
mal tire wear may indicate the need for alignment
service. Tire inflation pressure should be checked by
the owner at least monthly, or more often if daily
visual inspection indicates the need.
Exhaust SystemCheck complete exhaust system and nearby body
areas and trunk lid for broken, damaged, missing orm&positioned parts, open seams, holes loose connec-
tions or other deterioration wiuch could permit ex-haust fumes to seep into the trunk or passenger
compartment. Dust or water in the trunk may be an
indication of a problem in one of these areas. Any
defects should be corrected immediately. To help
insure continued integrity, exhaust system pipes and
resonators rearward of the muftler must be replaced
whenever a new mufIler is installed. Use genuine
GM parts specified for the vehicle.
Engine Drive BeltsAdjust belts driving fan, alternator and other acces-
sories at first 4 months or
6,ooO miles of vehicle
operation. At each subsequent 4 month/6,000 mile
interval, check belts for cracks, fraying, wear and
tension. Adjust or replace as necessary. It is recom-
mended that belts be replaced every 24 months or
24,C00 miles, whichever occurs first.
Suspension and SteeringCheck for damaged, loose or missing parts, or parts
showing visible signs of excessive wear or lack of
lubrication in front and rear suspension and steering
system. Questionable parts noted should be replaced
without delay.
Safety Checks to be Performed by OwnerListed below are the safety checks that should be
made by the owner (items a thru t). These checks
should be made at least every 4 months or
6,ooOmiles, whichever occurs first, or more often when the
need is indicated. Any deficiencies should be brought
to the attention of your dealer or another service
outlet, as soon as possible, so the advise of a qualified
mechanic is available regarding the need for repairs
or replacements.
A. Steering Column Lock
_ Check for proper operat-
ion by attempting to turn key to LOCK position and
turning steering wheel with car stationary. Steering
wheel should turn as long as key remains in lock.
When key is removed steering wheel should lock.
Key should be removable only in LOCK position.
B. Lap and Shoulder Belts
- Check belts, buckles,
retractors and anchors for cuts, fraying or weakened
portions, loose connections, damage, and for proper
operation. Check to make certain that anchor
mounting bolts are tight.
C. Steering
- Be alert to any changes in steering
action. The need for inspection or servicing may
beindicated by “hard” steering, excessive free play or
unusual sounds when turning or parking.
D. Windshield Wipers and Washers
- Check operat-
ion of wipers, as well as condition and alignment of

CC-10 1973 OPEL SERVICE MANUAL
wiper blades. Check amount and direction of fluid
sprayed by washers during use.,
E. Defrosters - Check performance by moving con-
trols to “DEF” and noting
am$nmt of air directed
against the windshield.
I
F. Wheel Alignment and
Balabce - In addition to
abnormal tire wear, the need fbr wheel alignment
service may be indicated by a pull to the right or
!eftwhen driving on a straight and level road. The need
for wheel balancing is usually
iddicated by a vibra-
tion of the steering wheel or
se;+ tihile driving at
normal highway speeds.I
IG. Brakes
- Be alert to illumiriation of the brake
warning light or changes in braking action,
SUCK as
repeated pulling to one side, unusual sounds when
braking or increased brake pedal travel. Any of thesecould indicate the need for
brakk system inspection
and/or service.
H. Parking Brake and Transmission “PARK”
Mechanism
- Check parking brake holding ability by
parking on a fairly steep hill and restraining the vehi-
cle with the parking brake only.
eon cars with auto-
matic transmissions, check the holding ability of the
“PARK” mechanism by releasing all brakes after
the transmission selector lever hak been placed in the“P” position.
I. Glass
- Check for broken, scrritched, dirty or da-
maged glass on vehicle that
coulld obscure vision’or
become an injury hazard.
J. Lights and Buzzers
- Check all instrument panel
illuminating and warning lights,’ seat belt reminder
light and buzzer, ignition key
b&er, interior lights,
license plate lights, side marker! lights, headlamps,
parking lamps, tail lamps, brake lights, turn signals,
backup lamps, and hazard warding flashers. Have
someone observe operation of
&ach exterior light
while you activate the controls: The operation of
instrument panel warning lights is covered in the
“Starting and Operating“ section of your
Own&%
Manual.K. Transmission Shift Indicator
‘- Check to be sure
automatic transmission shift
indiCator accurately i”-
dicates the shift position selected.
I
CAUTION: Before making thk check below,I
be sure to have a clear dist&e ahead and:
behind the car, set the parking brake and
firmly apply the foot brake.
Do not depress
accelerator pedal. Be prepared to
turn off ’
ignition switch
immediat+y if engine
should start.L. Starter Safety Switch (Automatic Transmissibn
Cars)
- Check starter safety switch by placing the
transmission in each of the driving gears while
at-tempting to start the engine. The starter should oper-ate only in the Park (“P”) or Neutral (“N”)
positions.
M. Horn
- Blow the horn occasionally to be sure thatit works. (Ignition switch must be in the “ON” posi-
tion.)
N. Seat Back Latches
- Check to see that seat back
latches are holding by pulling forward on the top of
each folding seat back.
0. Rearview Mirrors and Sun Visors
- Check that
friction joints are properly adjusted so mirrors and
sun visors stay in the selected position.
P. Door Latches
- Check for positive closing, latch-
ing and locking.
Q. Hood Latches - Check to make sure hood closesfirmly by pressing on the hood at the latching point
after each closing. Check also for broken, damaged
or missing parts which might prevent secure latch-
ing.R. Fluid Leaks
- Check for fuel, water, oil or other
fluid leaks by observing the ground beneath the vehi-cle after it has been parked for a while. If gasoline
fumes or fluid are noticed at any time, the cause
should be determined and corrected without delay
because of the possibility of fire.
S. Exhaust System
- Be alert to any change in the
sound of the exhaust system or a smell of fumes
which may indicate a leak.
Head Restraints
- Check that no head restraint
components are missing, damaged or loose. (Does
not apply to GT Models).
Disc BrakesCheck brake pads and condition of rotors while
wheels are removed during tire rotation. (Note belowregarding more frequent checks also applies to disc
brakes.)
Parking and Drum BrakesCheck drum
brake linings and other internal brake
components at each wheel (drums, wheel cylinders,
etc.). Parking brake adjustment also should be
checked whenever drum brake linings are checked.
NOTE: More frequent checks should be
made if driving conditions a.nd habits result
in frequent brake application. When brakes
require relining, it is recommended thatyou use those genuine General Motors
parts specified for your car,and Delco fluid
as required.

CONTENTS
SubjectPage No.
DESCRIPTION AND OPERATION:
Power
BrakeBooster. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Master
Cylinder
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS:
Power
Brake
,UnitTroubleDiagnosis. . . . . . . . . . . . . . . . . . . . . . . . . .MAINTENANCE AND ADJUSTMENTS:
Checking Brake Booster Operation
. . . . . . . . . . . . . . . . . . . . . . . . . . . .Brake Booster Filter Service
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Vacuum Control Valve Service
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
5A-2
5A-2SA-4SA-5
5A-65A-6
Brake Booster Removal and Installation
. . . . . . . . . . . . . . . . . .Master Cylinder Overhaul
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . . . . . . . . . . .SPECIFICATIONS:
General
Specifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SA-6
5A-7
5A-95A. 21973 OPEL SERVICE MANUAL
POWER BRAKE BOOSTER AND MASTER CYLINDER
DESCRIPTION AND OPERATION
POWER BRAKE BOOSTERThe vacuum power cylinder contains the power pis-
ton assembly which houses the control valve and
reaction mechanism and the power piston return
spring. The control valve is composed of the air valveand the floating control valve assembly. The reaction
mechanism consists of a hydraulic piston, reaction
plate, and a series of springs. An air filter element is
assembled around the push rod and fills the cavity
inside the hub of the power piston. This keeps dirt
and dust from entering the vacuum booster. The
push rod, which operates the air valve, projects out
of the end of the power cylinder ‘housing through a
boot.MASTER CYLINDER
The master cylinder is composed pf a primary pistonand secondary piston; it is supplied with fluid from
two separate reservoirs. A check valve is mounted onthe primary circuit which supplies fluid to the rear
brakes. This keeps a slight static pressure in the rear
brake system. When the pedal is depressed, the pushrod moves the two pistons forward simultaneously
until the seals of the two pistons cover the compen-
sating ports in the cylinder. The pressure is increasedin the two chambers simultaneously, thus supplying
fluid to both front and rear brake systems.Figure
5A-1 Brake Booster Attachment (Opel 1900
and Manta)
In the GT, the brake fluid container is arranged at
right angles to the tandem brake master cylinder. SeeFigure
5A-3. It is pushed over the feed port of the
rear brake circuit onto the brake master cylinder and

POWER BRAKE BOOSTER AND MASTER CYLINDER5A- 3
Figure 5A-2 Exploded View Master Cylinder (Opel 1900 and Manta)
held in position by a retaining plate. The front brake
circuit is connected to the brake fluid container by a
hose and a connector. See Figure
5A-4.An offset brake actuating rod, consisting of pedal
rod, adjuster and connecting tube, is used between
the brake pedal, the tandem brake master cylinder
and brake booster respectively. The connecting tube
is pressed onto the pedal rod and adjuster. The speci-
fied brake pedal free travel of
l/4 inch is obtained by
adjusting the brake booster piston rod and lock nut
of the adjuster.
VACUUM CONTROL VALVEhose between the intake manifold and the brake
booster and serves to prevent air from flowing back
(vacuum release) when the engine is shut off. See
Figure 5A-5.
This valve cannot be disassembled andmust be replaced when defective. To do this, the
short hose should be used between the intake mani-
fold and the vacuum control valve and the long hose
between the vacuum control valve and the brake
booster. Arrows on the valve housing indicate its
correct position in the line. Should a vacuum control
valve be installed backward no air could be drawn
out of brake booster, thus rendering it inoperative.
Hose clamps should be installed to prevent the possi-
bility of vacuum leaks.
A vacuum control valve is installed into the vacuum

POWER BRAKE BOOSTER AND MASTER CYLINDER5A- 5ConditionGrabby Brakes (Apparent
Off-and On Condition)
Possible Cause1. Broken or damaged
hydraulic brake lines.Correction1. Inspect and replace, as
“CXXSSary.2. Insufficient fluid in
master cylinder.
3. Defective master cylinder
seals.4. Cracked master cylinder
casting.2. Fill reservoirs with approved
brake fluid check for leaks.
3. Repair or replace, asnecessary.4. Replace
5. Leaks at front disc brake
calipers or rear wheel
cylinders
in pipes or connections.5. Inspect and repair, as
necessary.Brakes Fail to Release6. Air in hydraulic system.
1. Blocked passage in power
piston.
2. Air valve sticking shut.6. Bleed system.
1. Inspect and repair or replace,
as necessary.
2. Check for proper lubrication of
air valve “0” ring.
3. Broken piston return spring
3. Replace
master cylinder.
4. Tight pedal linkage.5. Repair or replace, as
necessary.
MAINTENANCE AND ADJUSTMENTS
CHECKING BRAKE BOOSTER OPERATIONThe operation of the brake booster can be checked by
simple means and without any special devices.
1. With engine off, first clear the booster of any
vacuum by depressing brake pedal several times.
2. Then depress brake pedal and start engine. If the
vacuum system is working correctly, the brake pedal,
kept under even foot pressure, moves farther down-
wards due to the additional pressure developed by
the booster. Should the brake pedal not move farther
downwards, the vacuum system is deficient. In this
case check the vacuum hose to booster, to vacuum
control valve and to engine intake manifold connec-
tions.3. If the vacuum system operates properly, the defect
is in the brake booster itself. A dirty filter impairs oreven prevents air from entering into the booster and
thereby the formation of a difference in pressure in
the vacuum cylinder.
Repairs cannot be carried out on the brake booster.
If no deficiency can be found in the vacuum system
or filter, the brake booster has to be replaced.
Under normal operating conditions the brake
booster requires no service. However, under adverse
conditions such as frequent driving on sandy or
dusty roads, the filter and sound deadener should be
replaced occasionally. To do so, the brake booster
must be removed but it isn’t necessary to detach the
master cylinder.
BRAKE BOOSTER FILTER SERVICEUnder normal operating conditions the filter need
not be exchanged for a new one.
Under adverse operating conditions
- frequent driv-