1973 OPEL GT-R engine

ENGINE MECHANICAL AND MOUNTS6A- 27
With feeler gauge, check gear backlash. It should be
between
.I?04 in. and .C!OS in. See Figure 6A-46.3. Remove (2) bolts holding pipe and screen assem-
bly to cylinder block. See Figure 6A-47.
FEELERGAUGE6A-46
Figure 6A-46 Measuring Oil Pump Gear Backlash
Checking Oil Pump Relief Valve
For Proper Functioning
1. Unscrew plug and check spring and relief valve
plunger in oil pump cover for dirt particles and free
operation. If required, carefully clean plunger and
seat. Pressure relief plunger sticking as a result of
foreign material or sludge build-up in the oil pump
cover can cause loss of oil pressure.
Removal and Inspection of Oil Pump
Pipe and Screen Assembly
1. Remove oil pan.
2. Clean oil pan. Make sure the gasket surfaces and
pan and block are clean.
Figure 6A-47 Installation of Pipe and Screen
Assembly4. Clean the screen and housing thoroughly in sol-
vent and blow dry with air stream.
Installation of Oil Pump and Screen Assembly
Install by reversing removal procedures, paying par-
ticular attention to the following points.
1. Make sure oil pump pipe flange gasket surface of
block is smooth and free of dirt.
2. Use a new gasket and install assembly.
3. Tighten pan bolts evenly. Do not over-tighten.
Torque to 5 lb. ft.
SPECIFICATIONSBOLT TORQUE SPECIFICATIONS
Use a reliable torque wrench to tighten all parts listed, to insure proper
tightness without straining or distorting parts. These specifications are for
clean and lightly-lubricated threads only; dry or dirty threads produce in-
creased friction which prevents accurate measurement of tightness.

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.

GA. xl1973 OPEL SERVICE MANUAL
Valve Seat and Correction Angle in Cylinder Head
Intake
Valve Seat Angle ..,._,..__....,,..,,,..,.,.,.,..............,............................................................... 45”Outer Correction
.,,,.,,._.,._..___,,,.,,,,,.......,,.,..,...,,..,..,,..,,..,,,.............................................. 30”
Exhaust
Valve Seat Angle
,,,.,,.__,.__..___.,..,,..,...,,....,..,..,..,,..,..,...,..,,,...,,......................................... 45”
Outer Correction
.,,..,,...,._.,.__....,,,.....,,,........................................................................... 30”
Valve Face Angle
,,..,,,..,.__..__.._..,,,..,,...,,......,.,..,..,..,,.,,,..,..,,,..,,,..,,,...,,................................ 44”Valve Seat Width in Cylinder Head
Intake
. . . . . . . . . . .._..._._.................,,..,.....,,..,............,...,..,,,..,,..,,...,,...,,,..,..................049-,059 In.
Exhaust
.,..,,,..,,.___..,,..,,...,..,,,..,,...,,...,,...............,,..,,..........,,....,,...,..................... .063-,073 In.Valve Head Contact Area
,,..,,,..,,___.__.,,..,,..,.,,..........,...,,..,,............,,,...,....... Aim at Centricity
Valve Clearance at 176°F. Coolant and 140°F. to 176”
Oil Temperature
Intake and Exhaust
_.,,..,,,,,,..,,....,...,,,.,.,,,.,..........................,,,..,,,,.... Zero Plus One Turn
Cranking MechanismMax. Permissible Out-of-Roundness of Connecting Rod Bearing
Journals
.....................................................................................................................OC02 In.
Max. Permissible Taper of Connecting Rod and Crankshaft Bearing
Journals
.....................................................................................................................ooO4 In.
Max. Permissible Radial Runout of Center Main Bearing
JournalsWhenSupportedinEndBearings
...........................................................0012In.Max. Permissible UnparalYelism of Connecting Rod Bearing
Journals When Crankshaft is Placed in V-Blocks so That
Main Bearing Journals Next to Each Other Are Supported
................................0005 In.
Max. Permissible Runout of Crankshaft to Flywheel
Contact Area
...........................................................................................................0008 In.
Crankshaft End Play
.........................................................................................GOl7-.CO61 In.
MainBearingClearance
.....................................................................................ooO9-.@I25In.Connecting Rod Bearing Clearance
.................................................................ooO6-.0025 In.
Connecting RodEnd PlayonBearing Journal
...............................................0043-.0095In.Connecting Rod Bearing Length
.......................................................................7785-.7992 In.
CrankshaftThrustBearingLength
..............................................................................1.08In.
Valve MechanismCamshaft Bearing Clearance
.................................................................................OOl-,003 In.
Camshaft End Play
...............................................................................................004-038 In.
Max. Permissible Radial Runout of Camshaft Center Bearing
- Camshaft Supported in Outer Bearings................................................................,001 In.
ValveLifter Clearance in Cylinder HeadBore
...............................................0003-.OOl3In.
Engine Lubricating SystemOil Pump Gear Backlash
......................................................................................0%.008 In.
Oil Pump Gear End Play in Housing
........................................Gears Protruding Over Edge
of Housing: Not More Than
,004 In.
Clearance of Spindle in Bore of Oil Pump Driven
Gear
...............................................................................................................OCO3-.0015 In.
Clearance Between Oil Pump Drive Gear and
Bushing
.........................................................................................................00035-.OOl5 In.
Oil Pump Relief Valve Spring Pressure at a Spring Length
of
.8 In..................................................................................................................44-.66 Lbs.

ENGINE MECHANICAL AND MOUNTS6A- 31

66.321973 OPEL SERVICE MANUAL
COOLING SYSTEM
CONTENTS
Subject
DESCRIPTION AND OPERATION:
Cooling System and Water Pump
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS: (Not Applicable)
MAINTENANCE AND ADJUSTMENTS:
Checking and Filling Cooling System
. . . . . . . . . . . . . . . . . . . . . . . .Draining
andFlushingCoolingSystem. . . . . . . . . . . . . . . . . . . . . .Conditioning the Cooling System
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Using and Testing Anti-Freeze Solutions
. . . . . . . . . . . . . . . . . .Fan Belt Adjustment or Replacement
. . . . . . . . . . . . . . . . . . . . . . . .Radiator Thermostat Inspection and Test
. . . . . . . . . . . . . . . .MAJOR REPAIR:
Water Pump Removal
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Radiator
Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SPECIFICATIONS:
Cooling System Capacities
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page No.
68-32
6B-32
68-32
68-33
68-33
68-33
68-33
68-34
68-34
6B-35
DESCRIPTION AND OPERATION
COOLING SYSTEM AND WATER PUMPThe coiling system is of the conventional pressurized
type. A centrifugal pump arranged in timing case
serves to circulate the coolant.
When the thermostat is closed, the coolant will re-
turn to the pump via a by-pass for swift and uniform
warming up of the engine the coolant circulates
through the radiator, only when the engine has
reached normal operating temperature.
The heater system branches off the cooling system
ahead of thermostat in flow direction so that the
heater is in operation before engine has reached full
operating temperature.
MAINTENANCE AND ADJUSTMENTS
Checking and Filling Cooling SystemThe coolant level should be checked only when the
engine is cold and only enough coolant should be
added to bring the level halfway between core andtank top. It is unnecessary and undesirable to remove
the radiator cap and check the coolant level each
time the car stops at a filling station for gasoline or
oil, since the engine is usually hot at such times.
WARNING: Never remove the radiator cap quickly
when engine is HOT Sudden release of cooling
sys-
tern pressure may cause the coolant to boil and some
of it may be ejected from the radiator
filler neck,
resulting in
inl’ury to persons or damage to the car
finish.If it is necessary at any time to remove the radiator
cap when engine is hot, rotate the cap counterclock-
wise until first stop is reached. Leave cap in this
position until all pressure in cooling system has been
released, then turn cap past the first stop and remove
it.
Draining and Flushing
Cooling SystemThe cooling system should be completely drained
and the recommended coolant installed every two (2)
years.To drain the cooling system, remove radiator cap,
remove lower radiator hose from the lower tank and

COOLING SYSTEM6B- 33
remove drain plug on right.side of cylinder block. Set
heater temperature control valve at full heat posi-
tion. After the cooling system is drained, and plugs
reinstalled, fill the system with clean water. Run the
engine long enough to open the thermostat for com-
plete circulation through the system, then com-
pletely drain the cooling system before sediment has
a chance to settle.
Conditioning the Cooling System
“Rust Inhibitor and Stop Leak”, or equivalent listed
under Group 8.800 is recommended for use in the
cooling system, particularly when preparing for in-
stallation of anti-freeze solution. This material stops
small seepage leaks, has rust preventive properties
and its soluble oil is effective in eliminating a squeal-
ing noise which sometimes develops at the water
pump seal washer. Instructions for its application are
printed on the conditioner bottle.
It is very important to make certain that the cooling
system is properly prepared before an anti-freeze so-
lution is installed, otherwise loss of solution through
leakage may occur or seepage may result in damage
to the engine. The cooling system should be drained
and flushed as described under Draining and Flush-
ing Cooling System. All joints should be checked for
leakage and corrected, and the conditioner described
above should be added with the anti-freeze solution.
Inspect the water pump, radiator core, heater and
defroster cores, water jacket plugs, and edge of cylin-
der head gaskets for evidence of water leaks. Tighten
all hose clamps in the cooling and heating systems
and replace any deteriorated hoses.
Using and Testing Anti-Freeze
Solutions
Inhibited year around (ethylene glycol type) engine
coolant solution which is formulated to withstand
two full calendar years of normal operation without
draining or adding inhibitors should be used at all
times. Freeze protection should be provided to pro-
tect against corrosion. When adding solution due to
loss of coolant for any reason or in areas where tem-
peratures lower than minus 20 degrees F. may be
encountered, a sufficient amount of any of the sev-
eral brands of year around coolant (Ethylene Glycol
base) compatible to GM Specification 1899-M avail-
able on the market should be used. Water or alcohol
base coolants are not recommended for this vehicle
at any time.
If for any reason water only is used as a coolant in
an emergency, it is extremely important that Buick
Heavy Duty Cooling System Protector and Water
Pump Lubricant or equivalent be added to the cool-
ing system as soon as possible. If any other cooling
System protector is used, be certain it is labeled toindicate that it meets General Motors Specification
GM 1894-M. It should be recognized that this is only
a temporary measure. The manufacture intends that
permanent type coolant solution be used year around
in the cooling system.
The cooling system should be completely drained
and the recommended coolant installed every two (2)years.It is advisable to test the anti-freeze solution at inter-
vals during the winter to make certain that the solu-
tion has not been weakened. Use only hydrometers
which are calibrated to read both the specific gravity
and the temperature, and have a table or other means
of converting the freezing point at various tempera-
tures of solution. Disregarding the temperature of
the solution when making the test may cause an error
as large as 30 degrees F. Care must be exercised to
use the correct float or table for the particular type
of anti-freeze being tested.
Fan Belt Adjustment or Replacement
A tight fan belt will cause rapid wear of the alterna-
tor and water pump bearings. A loose belt will slip
and wear excessively and will cause noise, engine
over-heating, and unsteady alternator output. A fan
belt which is cracked or frayed, or which is worn so
that it bottoms in the pulleys should be replaced. The
fan belt may be replaced by loosening the alternator
brace at alternator, slightly loosening the alternator
mounting bolts and moving alternator inward to pro-
vide maximum slack in the belt.
The alternator must be moved outward to adjust the
fan belt. After the generator brace and mounting
bolts are securely tightened, the fan belt tension
should be 45 lb. using Tensioner J-23600.
WARNING: Zfa
fan blade is bent or damaged in any
way, no attempt should be made to repair and reuse
the damaged part. A bent or damaged fan assembly
should always be replaced with a new
fal. assembly.
It is essential that fan assemblies remain in proper
balance and proper balance cannot be assured once
a fan assembly has been bent or damaged. A fan
assembly that is not in proper balance could fail and
fly apart during subsequent
we creating an ex-
tremely dangerous condition.
Radiator Thermostat Inspection and Test
A sticking radiator thermostat will prevent the cool-
ing system from functioning properly. If the thermo-
stat sticks in the open position, the engine will warm
up very slowly. If the thermostat sticks in the closed
position, the engine will overheat.
The thermostat may be removed for inspection and

6B- 341973 OPEL SERVICE MANUAL
test by partially draining the cooling system and dis-
connecting the water outlet housing from the ther-
mostat housing which is mounted on the right front
side of cylinder head.
The standard thermostat valve should start to open
at 189 degrees F and fully open at approximately 212
degrees F. If thermostat does not operate at specified
temperatures, it should be replaced as it cannot be
repaired.MAJOR REPAIR
WATER PUMP REPAIRSThe water pump bearing outer race is shrunk fit into
the water pump cover. For this reason the cover,
shaft bearing, and hub are not repairable.
Water Pump RemovalOpel radiators do not have a drain plug. Drain radia-
tor by first, loosening radiator cap, then remove
lower hose from lower radiator tank.
1. Drain coolant into a clean container. Remove
radiator and shroud.
2. Remove fan belt.
3. Remove fan blade and pulley on water pump shaft.
4. Disconnect inlet hose and heater hose from water
pump. Remove bolts, pump assembly and gasket
from timing chain cover.
5. Check pump shaft bearing for end play or rough-
ness in operation. If bearings are not in serviceable
condition, the assembly must be replaced.
Water Pump Installation1. Make sure the gasket surfaces on pump and timing
chain covers are clean. Install pump assembly with
new gasket. Bolts must be tightened uniformly.
Torque to 11 lb. ft.
2. Install radiator and shroud. Connect radiator hose
to pump inlet and heater hose to nipple.
3. Install fan pulley and fan blade, tighten attaching
bolts securely. Install belts and adjust for proper
tension.4. Fill cooling system and check
,for leaks at pump
and hose joints.
RADIATOR REMOVAL AND INSTALLATION
RemovalI. Loosen radiator cap, then remove lower radiator
hose and drain radiator coolant into suitable con-
tainer.
2. On vehicles with automatic transmission, unscrew
oil lines from connectors on lower radiator tank and
plug lines. On GT models with automatic transmis-
sion the lines have to be disconnected at the coupling
before removing from the tank. It is essential that no
dirt enters the oil lines. When unscrewing oil lines,
hold connectors on lower radiator tank with pliers to
avoid leakages. Ensure that no dirt enters oil cooler.
3. Remove lower attaching nut and slide radiator
upward and out of engine compartment.
Installation1. Install radiat,or into engine compartment and se-
cure lower attaching nut.
2. On vehicles with automatic transmissions, fasten
oil cooler lines to lower radiator tank. It is essential
that no dirt enters the oil lines. When tightening oil
lines, hold connectors on lower radiator tank with
pliers to avoid leakages. Ensure that no dirt enters oil
cooler. Torque to 1 I-15
lbs.ft.3. Install lower radiator hose and add collected coo-
lant.
All Opels are provided with a radiator initial fill of
an antifreeze solution containing corrosion inhibitor.
The antifreeze has either a glycol or glycerin base
and protects the engine against freezing, down to
minus 22 degrees F. (minus 30 degrees C.). Before
the start of the cold season, coolant must be checked
with a hydrometer and if necessary, brought to the
necessary specific gravity by adding anti-freeze with
a glycol or glycerin base. As the specific gravities of
all anti- freeze solutions having a glycol or glycerin
base are practically the same, the hydrometer can be
used for all these types. Because of the tolerances of
the hydrometer, or slight differences in specific
gravity, variations of plus or minus 5 degrees can be
expected. Coolant must be checked at a temperature
of plus 68 degrees F. (plus 20 degrees C.)