GMC X-7425 1973 User manual

X-7425
1973 GMC Motorhome
Maintenance Manual
Table of Contents
Section Description
0 Information, Periodic Maintenance and Lubrication
1 Body, Heating and Air Conditioning
2 Frame
3A Front Suspension
3B Drive Axles
3C Final Drive
4 Rear Suspension
5 Brakes
6A Engine
6K Engine Cooling
6M Engine Fuel System
6T Emission Control Systems
6Y Engine Electrical
7 Transmission
8 Fuel Tank and Exhaust
9 Steering System
10 Wheels and Tires
12 Chassis Electrical
13 Radiator and Coolant Recovery System
14 Bumpers
24 Miscellaneous Living Area Facilities
24A Periodic Maintenance and Lubrication
24B Living Area Electrical System
24C Motor Generator
24D Refrigerator
24E Roof Mounted Air Conditioner (Information not available at time of publication)
24F LP Gas System
24G Furnace
24H Range/Oven
24J Living Area Water System
24K Toilet
24L Holding Tank and Drainage System
24M Thermasan System
24N Cabinets and Furniture
24P Exhaust Vents
24Q Other Equipment (Vacuum Cleaner)
Wiring Diagrams

GMC
MOTOR
HOME
SERVICE
GENERA .L I ;NFO ~MAT

>s
PERIODIC MAINTENANCE
AND LUBRICATI
v

U
GENERAL
MOTORS CORPORATION
WARRANTY MAY BE VOIDED
IF WEIGHT
EXCEEDS ANY OF THE RATINGS
SHOWN .
GROSS VEHICLE WEIGHT INCLUDES WEIGHT
OF
BASEVEHICLE, ALL ADDED EQUIPMENT,
DRIVER
AND PASSENGERS, AND ALL PROPERTY
LOADED
INTO OR ONTO
VEHICLE .
GROSS VEHICLE WEIGHT
FOR THIS VEHICLE
MAXIMUM
FRONT END ,
WEIGHTAT GROUND

I
MAXIMUM REAR END
WEIGHT AT GROUND
VEHICLE
IDENT .
N0 .
RATINGS IN POUNDS
AS MANU-
FACTURE
A-2329
Figure 1-Vehicle Identification
Plate
VEHICLE IDENTIFICATION
Contents Of This Section Are Listed
Below :
SUBJECT

PAGE NO .
Vehicle

Identification

... . . . . . . ..................... . . ....... . . ...........................

. .

...... ...... . : :.....

: ; : ...: : . .. .
.
.. :, :
::. ;i : ... ., .  . . ... :0-1
Component Identification
0-2
Hoisting Instructions
.... . . . . ..................... . . ......... .................. . .................... . . . . . . . ................. . . .... . . ..................
. . . . ................ .... . . . ... .0-2
Jack Usage Instructions
..................... . . .... . . . . ................... . ................. . . . . . . . . . .................. . . .... . . .................. .
. . ................. .... . . . .... 0-3
Towing Motor Home
. . .... ...................... ...., .. . . . . ................... . .............. . . . . . ..... . . ..: :, .......... . . . . .
..: :... . . . . ............ . . . . ............... . . ... . . . . ... .0-4
Engine, Chassis, and Body Maintenance Schedule . . . . . ... . ...

. . . . . . ., . .

..........
. . . . . . ......... . ..... . . ... ... . ....
0-6
Explanation
of
Maintenance Schedule ........................ . .......... ., . . . . . . . .... . . ................ . . . . . . . . .................. . . . . . . .........
. ..... . . ... . . . . .... 0-7
Recommended Fluids and
Lubricants ....................... . . . . . . . . . . . . . . . . . . . . . .
.
..
. . . . ...

...... . . . . . ... .............
. . . ... ........

. .

. ., . . 0-10
Lubrication
..
Winterization and
Vehicle Storage . . . ..................... . . . . . . . . . . . . . . . . . . . . . . . . . . . .................. . . .... ....................
. . .... ............ . . . . . .... ..... . .... 0-15
The Vehicle Identification and
Weight Rating
Plate (figure 1) located behind the right
front access
door shows the "Vehicle Identification Number",
and the
`
.` .As
Manufactured"' Gross Vehicle - Weight
Rating
for
the
MotorHorne to whicb - it'is attached .
In order that the vehicle may be specifically iden-
tified as to manufacturer, engine type, year of manu-
facture, etc ., refer to Figure 2 .
(TYPICAL IDENTIFICATION NUMBER TZE033V100053)
MODEL DESIGNATION
Code Model Length
03 230 23'
SERIES 06 260 26'
03
MFD .
B Y
GMC
ENGINE
TYPE
E-V8 Gasoline

SEQUENTIAL
NUMBER
1 00053
ASSY .
PLANT
CODE
V-Pontiac
A-0853
Figure 2-Vehicle Identification Number

0- 2

GENERAL INFORMATION
COMPONENT IDENTIFICATION
ENGINE
Motor Home engines are identified by a code
tape installed directly above the engine serial number
which is stamped on the engine oil fill tube (figure 3) .
TRANSMISSION
The transmission
model and code
numbers are
stamped on the
converter housing as shown
in Fig-
ure 4 .
FINALDRIVE
The ratio and
date codes are stamped on the
flange
near the right hand spreader hole as shown in
Figure
5 .
Date Code : The code letter is for the month
and
the number(s) are for actual date .
Ratio Code : "T" = 3 .07 :1

EXAMPLE : T
A12 = 3 .07 :1,
built January 12 (J = 9th month, I
is not
used) .
Figure
3-Engine Identification
A twin post hoist of sufficient
capacity and with
proper adapters and/or fittings
must be used .
Front hoisting position is the front engine cross-
member
.
HOISTING INSTRUCTIONS
Figure 4-Transmission Serial Number
Plate
Figure 5-Final
Drive Identification
Rear hoisting must be
done at the rear suspension
brackets . If an "I"
beam type adapter is used it
shouldbe approximately
82 inches in length to gain
adequate support at suspension brackets . (figure 6)

If vehicle is to be placed on jack stands for
maintenance or repairs, the hoisting points should be
used .
CAUTION : To help avoid serious
damage to
your Motor Home, the vehicle
should be
raised only on twin post
hoists of 15,000
pounds or more
total rated capacity, at the
suspension
points noted (see diagram) .
Before
raising, check overhead clearance to
see that it is sufficient
for the Motor Home .
Do
NOT
use the
vehicle jack for hoisting or
maintenance
. It is designed for use only
when
changing tires .
JACK USAGE INSTRUCTIONS
CAUTIONS
1 . Follow jacking instructions in order to reduce
the possibility of serious personal injury .
. 2 . The jack is designed for use only when chang-
ing wheels .
3 . Never get beneath the vehicle when using jack .
4 . Do not start or run engine while vehicle is on
jack .
INSTRUCTIONS
Park on level surface and set parking brake
firmly .
Set transmission in "PARK" .
Activate Hazard Warning Flasher .
Jack, jack chain, handle, "jacking pad"
(wooden block), and lug wrench are located under
dinette seat .
Block both front and rear of the wheel diagon-
ally opposite the jack position .
Loosen but do not remove wheel nuts .
JACKINGAT FRONT-Place hydraulic jack
on wood block near energy absorbing front bumper
bracket . Place hook at flange of front cross-member .
Pass chain under bumper and adjust chain length to
snug fit on fork on
top of jack (See figure 7) .
dle
.
GENERAL INFORMATION

0- 3
FRONTENGINE

REAR SUSPENSION
CROSSMEMBER

BRACKETS
DENOTES
APPROVED LIFTING
POINTS
A-1941
Figure
6-Motor Home Hoisting Points
JACKING AT REAR-Place hydraulic jack
on wood block close to rear suspension bracket (See
figure 8) . The hook is placed in the drainage slot
under bracket . Adjust chain length so link will fit in
fork
at top of jack
.
Close valve
at
base of
jack
and insert jack ban-
Figure 7-Jacking at Front of Motor Home

0- 4

GENERAL INFORMATION
Figure 8-Jacking at
Rear
of
Motor Home
Always operate jack with slow, smooth motion
.
Raise vehicle so tire just clears surface,
replace
wheel and slightly tighten wheel
nuts .
Open valve at base of jack to lower, then
fully
tighten wheel nuts . Proper torque is 250 foot
pounds .
CAUTION : Use lug wrench provided to
tighten wheel nuts securely if torque wrench
is not available .
(Follow the nut tightening
sequenceshownin
WHEELSAND TIRES,
Section
10 of
this
manual . At the earliest
opportunity have
wheel nut torque checked .
This is
necessary to help prevent loosening
or
stripping
of
the wheel nuts .
TOWING MOTOR HOME
Proper lifting or towing equipment
is necessary
to
prevent
damage to the GMC Motor Home during
any towing
operation . State (Provincial in Canada)
and local
laws applicable to vehicles in tow must also
be followed .
The Motor Home may be towed on
all
six
wheels
at speeds of less than 35 MPH, for
distances
up to 50 miles, provided final drive, axle,
and transmission
are otherwise normally operable .
For such towing, parking
brake must be released,
transmission must
be
in neutral,
and the ignition key
turned to OFF position .
TOWING AT FRONT (FIGURE
9)
NOTE : Attachments must be to frame front
crossmember of the Motor Home, not to bump-
ers or bracketing . Separate safety chains or ca-
bles should be used . Care must be talon in
installation of chains to ensure that they do not
cause damage . Remember that power brake and
steering assists will not be available when engine
is inoperative .
Certain other precautions are required when it is
necessary to tow with the front drive wheels lifted off
the road . On Motor Homes equipped with the Power
Level System, turn the valve dials, below the instru-
ment panel, to "HOLD" position, thereby making
the automatic height valves inoperative on the rear
suspension . On Motor Homes not equipped with the
optional Power Level System it will be necessary to
disconnect the height control valve link arm at the
rear suspension control arm (adjacent to the shock
absorber stud) on each side of the vehicle (figure 10) .
Raising front of vehicle so front wheels are four
in-
ches off the ground will provide about five-inch
ground clearance at the rear when towing .

TOWING ATREAR
It
is
not recommended that vehicle be towed with
the rear raised as this could result in suspension or
crossmember damage .
Figure 9-Typical Towing
Hook-up
GENERAL INFORMATION

0- 5
Figure 10-Disconnecting Leveling
Valve Link Arm

0- 6

GENERAL INFORMATION
ENGINE,
CHASSIS, AND BODY
MAINTENANCE
SCHEDULE
LUBE AND GENERAL MAINTENANCE
SAFETY MAINTENANCE
EMISSION CONTROL
MAINTENANCE
WHEN TO PERFORM SERVICES
(Months or Miles, Whichever Occurs First)
Item
No .
SERVICES
(For Details, See Numbered Paragraphs)
Every 3 months or 3,000 miles 1
Chassis Lubrication
2 Engine
Oil
Every 6 months or 6,000 miles 3 Fluid Levels
4 Air Conditioning System
5 Air Compressor Air
Filter
Every 6,000
miles (Check wheel
nut torque
after 1st 500 miles)
6
Wheel and Tires
At
1st
oil
change and then every 2nd 7 Engine Oil Filter
Every 12
months or 12,000 miles 8 Automatic Transmission and Final Drive
9 Cooling System
Every 24,000 miles
1
0Rear
Wheel Bearings
11 Final Drive
Boots & Output Shaft Seals
Every 6 months or 6,000 miles 12 Brakes and Power Steering
13 Exhaust System
14 Drive
Belts
15 Suspension and Steering
16 Owner Safety Checks
Ever 6,000 miles 17
Disc Brakes
Every 12 months or 12,000 miles'!
18 Drum
Brakes
and Parking Brake
19 Throttle Linkage
20 Headlights
21 Underbody
22 Bumpers
At 1st 6 months or
6,000 miles - 23 Thermostatically
Controlled Air Cleaner
then at 12 months/12,000
mile
24 Carburetor Choke
intervals
25
Timing, Dwell, Carb . Idle, Distributor
& Coil
At 1st 6 months or 6,000 miles
26 Carburetor & Intake Manifold Mounting
Every 6,000 miles
27 Sark Plugs (When using leaded
fuels)
Every 12 months or
28 Thermal Vacuum Switch and
Hoses
12,000 miles
29 Carburetor Fuel Filter
30 PCV System
31 Air Cleaner Element
32 Spark Plugs and Ignition Coil Wires
Every 24 months or
33 Engine Compression
24,000 miles
34 ECS System
35 I Fuel Cap . Tanks and Lines

EXPLANATION OF
MAINTENANCE SCHEDULE
Presented below is a brief explanation of each of
the services
listed in the preceding Maintenance
Schedule .
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 requirementsare included where appli-
cable .
LOBE AND
GENERAL
MAINTENANCE
ITEM
NO . SERVICES
1 CHASSIS-Lubricate all grease fittings
in front
and rear suspension and steering linkage .
Also lubri-
cate transmission shift linkage, brake
pedal spring,
parking brake cable guides and linkage
.
2 ENGINE OIL-Change each 3 months or 3,000
miles, whichever occurs first .
3 FLUID LEVELS-Check
level of fluid in brake mas-
ter cylinder, power steering pump, all batteries, en-
gine, final drive, transmission, and windshield
washer . The engine
coolant shouldbe checked for
proper level
and freeze protection to at least -35°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 mean that a malfunction is developing
and corrective action shouldbe taken immediately .
A low fluid level in the brake master cylinder front
reservoir could also be an indicator that the disc
brake pads need replacing .
4 AIR CONDITIONING-Check condition of air con-
ditioning system hoses and refrigerant charge at
sight glass
. Replace hoses
and/or refrigerant if need
is indicated .
5
AIR COMPRESSOR-Filter
shouldbe
washed with
soap and water solution or replaced .
6 WHEELS AND TIRES-Have wheel-nut torque
checked after 1st 500 miles and 500 miles after every
wheel replacement thereafter . Check tires for exces
sive wear, nails, glass, cuts or other damage . Make
certain wheels are not bent or cracked . Uneven or
abnormal tire wear may indicate the need for align-
ment service . Tire
inflation
should be
checked
GENERAL INFORMATION

0- 7
monthly or more often if visual inspection indicates
a need and after each tire rotation . Adjust pressure
if required, as shown on tire placard on glove box
door .
7 ENGINE OIL FILTER-Replace at the first oil
change and every 2nd oil change thereafter .
8 AUTOMATIC TRANSMISSION FLUID AND FINAL
DRIVE LUBRICANT-Change the transmission fluid and
filter ; change final drive lubricant .
9 COOLING SYSTEM-At 12-month or 12,000-mile
intervals, wash radiator cap and filler neck with
clean water, pressure 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 12,000 miles, clean ex-
terior of radiator core and air conditioning con-
denser . Every 24 months or 24,000 miles, drain,
flush, and refill the cooling system with a new coo-
lant solution .
10 WHEEL BEARINGS-Clean and repack rear
wheel bearings with a lubricant as specified in the
"Recommended
Fluids and Lubricants" chart .
11 FINAL DRIVE AXLE BOOTS AND OUTPUT SHAFT
SEALS-Check for damaged, torn or leaking boots on
drive axles and for leaking output shaft seal . Replace
defective parts as necessary .
SAFETY MAINTENANCE
12 BRAKES AND POWER STEERING-Check lines
and hoses for proper attachment, leaks, cracks, chaf-
ing, 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 .
13 EXHAUST SYSTEM-Check complete exhaust
system and nearby body areas of vehicle engine and
motor-generator system for broken, damaged, miss
ing or mispositioned parts, open
seams, holes, loose
connections or other deterioration which
could per-
mit exhaust fumes to seep into the passenger
com-
partment . Dust or water in
the passenger
compartment may be an indication of
a problem in
one of these areas . Any defects
shouldbe corrected
immediately . To help
ensure continued integrity, ex-
haust system pipes rearward
of the muffler must be
replaced whenever a new muffler is installed
.

0- 8

GENERAL INFORMATION
14 ENGINE DRIVE BELTS-Check belts driving fan,
Delcotron, power steering pump and air condition-
ing compressor forcracks, fraying, wear and tension .
Adjust or replace as necessary .
It is recommended that belts
be replaced
every 24
months
or
24,000
miles,
whichever
occurs first .
15 SUSPENSION AND STEERING-Check for da-
maged, loose or missing parts, or parts showing visi-
ble signs of excessive wear or lack of lubrication in
front and rear suspension and steering system .
16 SAFETY CHECKS
TO
BE PERFORMED
BY OWNER-
The maintenance schedule in
the Operating Manual
lists several items the owner should check and have
repaired
if
not functioning properly .
17 DISC BRAKES-Check brake pads and condition
of rotors while wheels are removed during tire
rota-
tion .
18 DRUM BRAKES AND PARKINGBRAKE-Check
durm brake linings and other internal brake compo-
nents at rear wheels (drums, wheel cylinders, etc .) .
Parking brake adjustment also should be checked for
drag and lubricated at every chassis lube period .
NOTE : More frequent checks should be made if
driving conditions and habits result in
frequent
brake application .
19 THROTTLE LINKAGE-Check for damaged
or
missing parts, interference or binding .
20 HEADLIGHTS-Check
for
proper aim . Correct
as necessary
.
21 UNDERBODY-In
geographic areas using a
heavy concentration of road
salt or other corrosive
materials
for snow removal or road dust control,
flush and inspect the
complete underside of the vehi-
cle at least onceeach year, preferably
after a winter's
exposure . Particular attention should
be
given
to
cleaning out underbody members where
dirt and
other foreign materials may have collected
.
22 BUMPERS-Check the front
and rear bumper
systems at 12-month/12,000-mile
intervals
to
be sure
the impact protection and clearance
originally de
signed into the system
remains in a state of full readi-
ness . It also shouldbe
checked whenever there is
obvious bumper misalignment, or whenever the vehi-
cle has been involved in a significant
collision in
which the bumper was struck, even
when
no
damage
to the bumper system can be seen
.
EMISSION
CONTROL
MAINTENANCE
23 THERMOSTATICALLY CONTROLLED AIR CLEAN-
ER-Inspect installation to make certain that all hoses
and ducts are connected and correctly installed . Also
check valve for proper operation .
24 CARBURETOR CHOKE-Check
chokemechanism
for free operation . Any binding condition
which may
have developed due to petroleum gum
formation on
the choke shaft or from
damage should be corrected .
25 TIMING, DWELL,
CARBURETOR IDLE, DISTRIBU-
TOR AND COIL-Adjust ignition
timing, dwell and car-
buretor idle speed
accurately (following the
specifications shown on the label
attached to engine
rocker cover) at the first 6months
or 6,000 miles of
operation then at 12 month
or 12,000 miles . Then at
12
month or 12,000 mile intervals
. Adjustment must
be
made with test equipment known
to be accurate .
Replace distributor
points every 12 months or
12,000 miles and replace
cam lubricator every 24
months or 24,000
miles . In addition, carefully
in
spect the interior
and exterior of the distributor
cap,
distributor rotor and coil
for cracks, carbon tracking,
and terminal corrosion .
Clean or replace as necessary
at 24-month/24,000
mile intervals to prevent misfir-
ing and/or deterioration .
Proper
functioning of the carburetor is particu-
larly essential to control of emissions . Correct mix-
tures for
emission compliance and idle quality
have
been preset by GMC Truck . Plastic idle
mixture li-
miters havebeen installed on the idle
mixture screws
to discourage unauthorized adjustment .
These idle
limiters are not to be removed unless some
major
carburetor repair or replacement which affects
the
idle screw adjustment has been necessary .
At 12 months or 12,000 mile intervals
or
in
case
of major carburetor overhaul, or when
poor idle
quality exists, the idle mixture shouldbe
adjusted by
use of a CO
meter when an accurate meter is availa-
ble,
or the alternate mechanical method shouldbe
used to adjust idle mixture (See SECTION 6M) .
26 CARBURETOR AND INTAKE
MANIFOLD MOUNT-
ING-Torque carburetor and
intake manifold attach-
ing bolts and/or nuts at first 6 months
or 6,000 miles
of vehicle operation .

27 SPARK PLUGS-Replace at 6,000 mile
intervals
when operating
with leaded fuels, or at
12,000-mile
intervals when
using unleaded fuels . Use of
leaded
fuels results in lead deposits
on spark plugs
and can
cause misfiring at
mileages less than 12,000 miles
.
Where misfiring
occurs prior to 6,000 miles, spark
plugs in good condition
can often be cleaned, tested,
and reinstalled in an engine
with acceptable results .
28 THERMAL
VACUUM SWITCH AND HOSES-Check
for proper operation
. A malfunctioningswitch
must
be replaced .
Check hoses for proper connection,
cracking, abrasion or
deterioration and replace
as
necessary .
29
CARBURETOR FUEL FILTER-Replace filter at 12-
month/12,000-mile intervals or more frequently if
clogged .
30 POSITIVE CRANKCASE VENTILATION SYSTEM
(PCV)-Check system for satisfactory operation at 12-
month or 12,000-mile intervals using a tester, and
clean filter . Replace the PCV valve at 24-month or
24,000-mile intervals and blow out PCV valve hose
with compressed air . The PCV valve should be re-
placed at 12-month or 12,000-mile intervals when
the vehicle is used in operations
involving heavy
dust, extensive idling, trailer pulling, and short trip
use at freezing temperatures where engine does not
become thoroughly warmed-up .
31 AIR CLEANER ELEMENT-Replace the engine air
cleaner element under normal operating conditions
every 12,000 miles . Operation of vehicle in dusty
areas will necessitate more frequent element
replace-
ment .
= 105) .
GENERAL INFORMATION

0- 9
CAUTION :
Do not operate the engine with-
out the air cleaner
unless temporary re-
moval
is necessary
during
repair or
maintenance of the vehicle . When the air
cleaner is removed backfiring can cause fire
in the engine compartment .
32 SPARK PLUG IGNITION COIL WIRES-In-
spect spark plug and ignition coil wires for evidence
of checking or cracking of exterior insulation and
tight
fit
in the distributor cap and at the spark plugs .
Exterior of
wires should be cleaned, any evidence of
corrosion on
ends removed and wire replaced if
deteriorated
.
33 ENGINE COMPRESSION-Test engine cranking
compression . If a problem exists, have correction
made . Minimum compression recorded in anyone
cylinder should not be less than 70% of the highest
cylinder .
For example, if the highest pressure in any
one cylinder is 1501bs ., the lowest allowable pressure
for any other cylinder would be 105 lbs . (150 X 70%
34 EVAPORATION CONTROLSYSTEM
(ECS)-Check
all fuel and vapor lines and hoses for
proper connec-
tions and correct routing as well
as condition .
Remove canister(s) and check for cracks
or damage .
Replace damaged or deteriorated parts as
necessary .
Replace filter in lower
section of canister .
If vehicle is equipped with two
canisters, filter is
located in the lower canister only .
35 FUEL CAP, FUEL LINES AND FUEL
TANKS-Inspect
the fuel tank capand lines for
damage which could
cause leakage . Inspect
fuel cap for correct sealing
ability and indications of physical
damage . Replace
any damaged or
malfunctioning parts .

0- 1 0

GENERAL
INFORMATION
RECOMMENDED
FLUIDS AND
LUBRICANTS

!
NOTE : Fluids and lubricants identified
with GM part numbers or GM specifica-
tion
numbers may be obtained from your
GMC Motor Home Service Outlet .
12
qts . after complete overhaul .
USAGE
FLUID/LUBRICANT
CAPACITIES
Engine oil
High quality SE
oil 5 qts .
(6 w/filter)
Power steering systema and
GM power steering fluid
Part No . 1 1/2
Qts .
pump reservoir . Includes
1050017 - if not available
use
windshield wiper
DEXRONDEXRON II
motor
automatic transmission fluid
Final drive
SAE-80 or SAE-90
GL-5 gear 4
Pts .
lubricant
(SAE-80 in Canada)
Brake system
and master cylinder Delco Supreme
11 or, DOT-3 fluid
or equivalent
Transmission shift linkage
Engine oil
Chassis lubrication
Chassis grease meeting
requirements
of GM 6031-M
Transmission
DEXRON or
DEXRON II 4
Qts .
automatic
transmission fluid
Parking brake
cables Chassis
grease
Rear wheel bearings
Chassis grease
meeting requirements
of GM 6031-M
Body door hinge pins, hinges
and Engine oil
latches at the front
access
doors, external
utilities,
generator/storage and LP
gas
doors . Gas fill door hinge
Windshield
washer solvent
GM Optikleen washer solvent
Part No . 1050001 or equivalent
Energizers (Batteries)
Colorless, odorless, drinking
water
Engine coolant
Mixture of water and
a high wuality 21
Qts .
Ethylene Clycol base
type
anti-freeze conforming
to GM
Spec . 1899-M

ENGINE
OIL AND FILTER
RECOMMENDATIONS
e Use
only SE engine oil .
LUBRICATION
DETAILS
ENGINE
* Refer to "Engine, Chassis and Body
Mainte-
nance Schedule" for oil change and filter
replace-
ment
intervals .
The
recommendations in the "Engine, Chassis
and Body
Maintenance Schedule" apply to the
first
change
as well as subsequent oil changes . The
oil
change
interval for the Motor Home engine is based
on the use of SE
oils and quality oil filters . Oil change
intervals
longer than those listed above will seriously
reduce
engine life and may affect GMC Truck
Coach's
obligation under the provisions of the New
Vehicle Warranty .
A
high quality SE oil was installed in the engine
at the
factory . It is not necessary to change this
factory-installed oil prior to the recommended
nor-
mal change period . However, check the oil level
more
frequently during the break-in period since
higher oil consumption is normal until the piston
rings become seated .
Figure 1 1-Engine
Oil Viscosity Chart
GENERAL INFORMATION

0- 1 1
NOTE : Non-detergent and other
low quality oils
are specifically not
recommended . Only the use
of SE engine oils and proper
oil and filter change
intervals assure of continued proper lubrication
of the Motor Home's engine .
RECOMMENDED SAE VISCOSITY
(FIGURE 11)
* Single grade oils are
preferred, however, multi-
grades such as SAE
1OW-30 or IOW-40 are also
acceptable .
* SAE
5W-20 oils are not recommended for sus-
tained
high speed driving .
e SAE
5W-30 oils (if available) may be used
if
extreme
low temperatures are anticipated .
SUPPLEMENTAL ENGINE OIL
ADDITIVES
The regular
use of supplemental additives
is
specifically not recommended
and will increase oper-
ating costs . However,
supplemental additives are
available that can
effectively and economically
solve
certain specific
problems without causing
other dif-
ficulties . For example,
if higher detergency is
re-
quired to reduce
varnish and sludge deposits
resulting from some
unusual operational
difficulty, a
thoroughly tested
and approved
additive-"Super
Engine Oil
Supplement"-is available at
your GMC
Motor Home
service outlet .
CHECKING OIL LEVEL
The engine oil should be maintained at
the 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 accumulation in the engine to
drain
back into
the crankcase . To check the level,
remove
the oil
level dipstick located inside the left front ac-
cess door
(See figure 12) wipe it clean and reinsert
it
fully for accurate reading . The oil level
dipstick is
marked "FULL" and "ADD ." (figure 13)
The oil
level should be maintained within the margin,
nei-
ther
going above the "FULL" line nor below
the
"ADD" line . Reseat the dipstick firmly after
taking
the reading .
One (1) quart will raise the oil level from
"ADD" to
"FULL ."
NOTE : The oil dipstick is also marked "USE SE
ENGINE
OIL," as a reminder to use only SE
oils .

0- 1 2

GENERAL INFORMATION
Figure
12-Removing Engine Oil
Dipstick
TRANSMISSION
The transmission dipstick and fill tube is located
under the engine access cover on the left side of the
engine . (figure 14)
Use only automatic transmission fluids identified
with the mark DEXRON(~) or DEXRON®11 .
These fluids have been
specially
formulated and
tested for use in the automatic transmission, and are
available from the GMC Motor Home service outlet
or local service station .
Check the fluid level at each engine oil change
period . Tomake an accurate
fluid level
check :
1 . Drive Motor Home several miles, making fre-
quent starts and stops, to bring transmission up to
normal operating temperature (approx . 180-190° F .) .
Figure 13-Engine Oil
Dipstick
Figure 14-Removing Transmission Dipstick
2 . Park Motor Home on
a
level
surface .
3 . Apply parking brake .
4 . Place selector lever in
"PARK" and leave en-
gine running .
5 . Open all but the two rear windows,
then
remove engine cover .
6 . Remove dipstick
and wipe clean .
7 . Reinsert dipstick
until cap seats .
8 . Remove dipstick
and note reading . (figure 15)
If fluid level is at
or below the "ADD" mark, add
sufficient fluid
to raise the level to the "FULL"
mark
. One pint raises the level from "ADD" to
"FULL ."
Do not overfill . Refer to the Maintenance
Chart for servicing schedule .
Figure
15-Transmission Dipstick

TRANSMISSION
OIL FILTER
REPLACEMENT
(FIGURE 16)
NOTE
: Have a drain pan
ready as lubricant
will
begin to
drain as bolts
are loosened .
1 . Remove
(13) bottom
pan attaching
screws .
2 .
Remove bottom
pan and discard
gasket .
3 .
Remove and discard
oil filter
assembly .
4 .
Install new O-ring
seal on new
filter and intake
pipe and
filter assembly
and install .
5 .
Using a new pan
gasket, install
pan . Torque
attaching
screws to
12 foot-pounds .
6 . Add four
(4) quarts of
DEXRON(~) or DEX-
RON
(~) II
automatic transmission
fluid and check
fluid as noted
above .
FINAL
DRIVE (FIGURE 17)
FINAL DRIVE
LUBRICANT
REPLACEMENT
1 . Remove (10)
cover attaching bolts . Have a
drain pan ready as lubricant
will begin to drain as
bolts are loosened .
2 . Remove
cover and allow lubricant to drain .
Discard old gasket .
3 .
Using a new cover gasket, install cover . Torque
attaching bolts to 24 foot-pounds . Shield to be bent
over breather hole .
4 . Add four pints of recommended lubricant
Figure 16-Replacing Transmission Oil Filter
GENERAL INFORMATION

0- 1 3
Figure 17-Final Drive Cover Removed
through fill plug hole or fill until lubricant level is at
the plug hole .
STEERING SYSTEM
POWER STEERING SYSTEM (FIGURE 18)
Check the
fluid level in the power steering pump
reservoir at each oil change period .
This requires the
removal of the engine access cover
. The reservoir is
located near the Delcotron . Add GM Power
Steering
Fluid (if GM Power Steering Fluid is not
available,
DEXRONQ or DEXRON(~)H Automatic
Trans-
mission Fluid may be used) as necessary to
bring
level into proper range on the filler cap indicator
depending on fluid temperature .
If at
operating temperature (approx . 150° F . -hot
to the touch) fluid should be between "HOT" and
"COLD" marks . If at room temperature (approx
.
70° F .)
fluid should be between "ADD" and
"COLD"
marks . The fluid does not require periodic
changing .
Figure 18-Checking Power Steering Fluid Level

REAR SUSPENSION
(2 FITTINGS
RIGHT
AND LEFT)
SIDE
OF VEHICLE
DRAG LINK ASSY .
(2 FITTINGS)
L .H . TIE ROD
(2 FITTINGS)
FRONT SUSPENSION
UPPER AND LOWER
BALL
JOINTS
(2
FITTINGS RIGHT AND
LEFTSIDE OF VEHICLE
R .H .
TIE ROD
(2 FITTINGS)
STEERING COLUMN
TO
GEAR SHAFT ASSY
.
(2
FITTINGS)
STEERING RELAY
LEVER
(1
FITTING)
A-1953

STEERING LINKAGE
(FIGURE
19)
The steering linkage (tie rods)
and suspension
should be lubricated, using a water resistant E .P .
Chassis Lubricant that meets GM Specification
6031-M, at every oil change . Seals should be
checked
for damage .
BRAKE SYSTEM
BRAKE MASTER
CYLINDER (FIGURE 20)
The master
cylinder is located behind the left-
side access door on
the front of the vehicle . The
fluid
level in the master
cylinder should be checked at
each oil
change . Wipe off the brake cylinder filler cap
and unsnap the retainer
. A low fluid level in the front
brake master cylinder
reservoir could bean indicator
that the disc
brake padsneed replacing . The
fluid
level must be maintained
at 1/4-inch below the top
of each
reservoir with Delco Supreme No .
11 or
DOT-3 Brake
Fluid or equivalent . When replacing
the cap be sure to
fasten the retainer securely, taking
care not to let dirt enter
the reservoirs .
GENERAL INFORMATION

0- 1 5
Figure 20-Checking Brake Master Cylinder
BLEEDING
BRAKES
The need for bleeding brakes is generally in-
dicated by springy, spongy pedal action . Pressure
bleeding equipment must be used and a definite
bleeding
sequence and procedure must be followed .
For
proper bleeding sequence see BRAKES (SEC-
TION 5) of this
manual
.
WINTERIZATION AND VEHICLE STORAGE
Winterization and vehicle storage are essential service functions which must
be performed on GMC Motor Homes . Details on theseitems are covered in
SECTION 24A "Periodic Maintenance and Lubrication"

GMC
MOTOR
HOME
SERVICE
SECTION 1
BODY,
HEATING AND AIR
CONDITIONING
This section includes the following :
SUBJECT

PAGE N0 .
. 1-1
Air Conditioning System (Includes
Heating) . . . ....... . ... . .... . ... . .... . ... . ..... . . ... . .... . .... . ... . . ... . . ... . .... 1-23
Heating System (Without Air
Conditioning) . . . ... . ... . ........ . ... . .... . ... . . .... . . ... . .... . .... . ... . . ... . . .... . ... 1-86
The body of the vehicle is constructed of alumi-
num and fiberglass with a wood floor . Extruded
aluminum ribs and struts are welded together to
form a cage-like framework . The exterior skin is then
bonded directly to the framework .
Both front and rear end caps are
fiberglass ; and
the lower side panels, below the belt line, are fiber-
All models have ignition and glove compartment
lock cylinders incorporating coded keyways and
BODY
Contents of this section are listed below
:
SUBJECT

PAGE N0 .
General Information
. ... . .... . .... . ... . . . . . . ... . .... . ........ . ... . . . . . ....... . . ........ . . ... . . . . . . ......... . ... . .
.. .
. .... .
. ... . . . . 1-1
Key
Information . .... . . ... . .... . .... . ... . . . . . . ... . .... . ........ . ... . ... . ....... . . ... . ..... .
...
.. ... . .... . .... . ... . .
... .
.....
. ... . . . . 1-1
Exterior Maintenance
. . . .... . .... . ... . . . . . . ... . .... . ........ . ... . ... . ........ . ... . ..... . ... . . ... . .... . .... . . . . . . ... . ..... .
... . .
..
1-2
Interior
Maintenance .... . .... . .... . ... . . . . . . ... . ............. . ... . ... . . ....... . ......... . ... . . ... . .........
. ... . . ... . ......... . . . . 1-2
Dust
and Water Leaks . . ... . .... . ... . . ... . ... . . ........ . ....... . ... . . . . . .... . .... . .... . ... .. .............
. . ... . ... ... ....... . . . . 1-3
Painting . ......... . ... . . ... . . .... . ... . .... . ... . . ... . ... . . .... . ... . ....... . .... . . . . ....
. .... . .... . ... . . ......... . ... . . ... . ... . . ......... . . . 1-4
Glass . .... . . ... . ..... . ... . . ......... . . . . . .... . ... . . ... . ... . . ........ .
.... . . . . . ... . ........ . ... . . ... . . ... . .... . .... . ... . . ... . . . . . . . .... . ... . . . 1-5
Windshield Wiper System . . ... .
. ... ..
.... . . . . ...... . . .
. .......
..
... . ... . .... . ... . . ... . . ... . .... . .... . ... . . ... . ... . . . .... . ... . . . 1-9
Entrance Door
. . . ..... . . ........ . .... . . . . . . ... . . . . . . .... . ... . .... . . . .... . ... . .... . ... . . .... . . . . . . ........ . .........
.
....
. .... . ... . . ... 1-12
Access Doors . ... . ..... . . .... . ... . .... . . . . . . ...
. .... . .... . ... . .... . . . . ... . ... . .... . ... . ..... . . . . . . .............. . ... . .... . .... . ... . . ...
1-15
Lap Belt Maintenance
.. . ... . .... . . . . . . ... . ... . . .... . ... . .... . . . . ....... . .... . ... . . .... . . . . . . ........ . ..... . ... . .... . .... . ... . . ...
1-16
Floor
.... . .... . .... . ... . ..... . . .... . ... . .... . . . . . . ... . . . . . .... . ... . ... . . . . . ... . ... . .... . ... . . .... . . . . . . ........ . .........
.
.. .
.. .... . .... . ... 1-16
Fiberglass Repair . .... . .... . ... . . ... . . . . . . ... . . ........ . ........ . ................. . .
. ..... . . ... . ......... . . . . . . ... . . .... . ... . . . . . . ... 1-18
Sheet Metal Repair . . .... . . . . . . ... . . . . . . ... . . ........ . ........ . ........................ . . . ... . .... .
.... . . . . . . ... . . .... . ... . . . . . . ... 1-19
Seats ..... . ... . ..... . . ... . .... . .... . . . . . . ... . . . . . . ... . . ... . .... . ........ . ... . ... . ......... . . . . . ... . . . . . . .... . .... . ... .
.
.. .
. . ... . . ... . . . . . . ... 1-19
Mirrors andSun Visor . . . . . . ... . . . . . . ... . . ... . .... . . ... . ... . ... . ... . ... . ..... . ... . ... . . ... . .... . ....
.. . . . . .... . .... . ... . . . . . . ... 1-20
Radiator Grille . ... . ..... . ... . . ... . ... . . ... . .... . .... . ... . . . . . . ... . ... . ... . ........ . . ... . ... . . ........
. . ... . . . . . . .... . .... . . . . . . . . . . ... 1-21
End Cap .......... . ... . ..... . ... . . ... . ... . . ... . .... . .... . . . . . . . . . . ... . ... . ........
. .... . ... . ... . . ........ . . ... . . ... . .... . .... . . . . . ........ 1-21
Special Tools . . . ... . ..... . ... . .
.. .
. .... .
...
.
... . . ... . . ... . . . . . . ... . ... . ............. . ... . ... . . .... . ... . . ... . . ... . .... . .... . . . . . ..... . . . 1-22
GENERAL INFORMATION
KEY INFORMATION
OCTOBER, 1973
glass . The side panels, above the belt line, are sheet
aluminum . The main roof panel is also
sheet alumi-
num .
The roof and side panels are bonded
directly to
the aluminum framing . Pop rivets
are then used to
secure the panels
where the roof and side panels are
joined and rivets are
also used at the belt line .
keys . The code
letter is located on the key shank and
the code number is stamped on
the knock-out por-

1- 2

BODY
tion of the key
head . These numbers
identify the
locks in which
the keys are used and are
required
when
ordering or making new keys .
The
other keys usedon the vehicle
have a metal
disc secured
to the keys . This number
should be
recorded
and the disc destroyed
as this number will
be needed
when ordering or making
new keys .
Entire vehicle should be
regularly inspected for
condition of paint and for corrosion
damage, with
particular attention given
to chrome . Inspection
should be made more frequently
in freezing weather
due to the corrosive effect of
road deicing materials
(salt, calcium chloride, etc .)
on metal . If inspection
discloses any evidences of
corrosion, paint failure, or
bare metal, corrective measures as outlined
under
"Painting" (later in this section) should
be immedi-
ately
employed .
Body painted
surfaces and chrome plating should
be protected by a coating
of wax, applied at regular
intervals . Periods
between applications should be
sufficiently
short to assure continuous protection
of
the finish
;
30
days after delivery, and at least
once a
Dust and loose dirt
that accumulate on interior
fabric trim
should be removed frequently with a
vacuum cleaner, whisk
broom or soft brush . Vinyl or
leather trim should
be wiped clean with a damp
cloth . Normal cleanable
trim soilage, spots or stains
can be cleaned with
the proper use of trim cleaners
available
throughGeneral
Motors Dealers or other
reputable supply outlets .
IMPORTANT :
Do not use commercial paint,
chrome or glass cleaners on interior
bright trim
or painted surfaces . If cleaning
is required, luke-
warm water and a neutral soap
may be used .
Before attempting to remove spots or stains from
upholstery, determine as accurately as possible the
nature and age of the spot or stain . Some spots or
stains can be removed satisfactorily with water or
mild
soap solution (refer to "Removal of Specific
Stains" later in this
section) . For best results, spots
or
stains
should be removed as soon as possible .
Some types
of stains or soilage such as lipsticks,
some inks,
certain types of grease, mustard, etc ., are
extremely difficult
and, in some cases, impossible to
completely remove . When
cleaning this type of stain
EXTERIOR
MAINTENANCE
INTERIOR
MAINTENANCE
Notch dept
information will be provided, on cur-
rent production
keys, upon request through the
manufacturer of your key
cutting equipment or his
locksmith association .
Also he will be able to furnish
a conversion
package for your cutter, if required,
fe
grinding
new keys .
year thereafter . Any
goodbody wax can be used for
both painted and chrome
surfaces . Wax should be
applied immediately
after vehicle has been cleaned .
NOTE : Calcium
chloride and other salts, road
tar, excretion from
insects, ("treesap"), chemi-
cals from factory chimneys
and other foreign
matter may permanently
damage paint and
chrome . Frequent, regular
washing and a
thorough cleaning after
exposure is recom-
mended to prevent damage by
these substances .
Use either
cold or lukewarm water . Never wash
vehicle in direct
rays of the sun and always wait
until painted surfaces have cooled .
or soilage, care must
be taken not to enlarge the
soiled area . It is sometimes
more desirable to have a
small stain thanan enlarged
stain as a result of at-
tempted cleaning .
CAUTION :

When cleaning interior
do not
use volatile cleaning solvents
such as : ace-
tone, lacquer thinners, enamel
reducers, nail
polish removers ; or such
cleaning materials
as laundry soaps, bleaches
or reducing
agents (except as noted in the instructions
on "Cleaning Fabrics" and
"Removal of
Specific Stains .') Never use carbon
tetra-
chloride, gasoline, or naphtha for any clean-
ing purpose . The
above materials may be
toxic or flammable,
or may cause damage to
interior .
INTERIOR GLASS
The interior glass surface
should be cleaned on a
periodic basis for
continued good visibility . A com-
mercial household
glass cleaning agent containing
ammonia will removenormal
tobacco smoke and

dust films sometimes caused by ingredients used in
vinyls, plastics, or other interior trim materials .
CLEANING FABRICS
IMPORTANT : Be sure vehicle is well ventilated
while using the following cleaning agents . Fol-
low manufacturer's recommendations in using
such products .
CLEANING FABRICS WITH
CLEANING
FLUID
This type of cleaner should be used for cleaning
stains containing grease, oil, or fats . Excess stain
should be gently scraped off trim with a clean dull
knife or scraper . Use very little cleaner, light pres-
sure,
and
clean cloths (preferably cheesecloth)
.
Cleaning action with cloth should be from outside of
stain towards center and constantly changing to a
clean section of cloth . When stain is cleaned from
fabric, immediately wipe area briskly with a clean
absorbent towel or cheesecloth to help dry area and
prevent a cleaning ring . If ring forms, immediately
clean entire area or panel section of the trim assem-
bly .
NOTE :
Sometimes
a difficult spot may require a
second application of cleaning fluid followed im-
mediately by a soft brush to completely remove
the spot .
CLEANING FABRICS WITH DETERGENT
FOAMCLEANERS
This type of cleaner is excellent for cleaning gen-
eral soilage from fabrics and for cleaning a panel
section where a
minor cleaning ring may
be
left from
spot cleaning . Vacuum area to remove excess loose
dirt . Always clean at least a full trim panel or section
of trim . Mask adjacent trim along stitch or weld
lines . Mix detergent type foam cleaners
in
strict ac-
cordance with directions on label of container . Use
foam only on a clean sponge or soft bristle brush-Do
not wet fabric excessively or rub harshly with brush
.
Wipe clean with a slightly damp absorbent towel
or
cloth . Immediately after cleaning fabric,
dry
fabric
Test windshield,
windows and vehicle under
flooring for leaks by spraying
water under pressure
DUST AND
WATER LEAKS
BODY

1- 3
with a dry towel or hair dryer . Rewipe fabric with
dry absorbent towel or cloth to restore the luster of
the trim and to eliminate any dried residue .
REMOVAL OF SPECIFIC
STAINS
CANDY-Chocolate, use cloth soaked
in luke-
warm water ; other than
chocolate, use very hot wa-
ter . Dry if necessary,
clean lightly with fabric
cleaning fluid .
CHEWING GUM-Harden
gum with ice cube
and scrape oft' with dull knife .
Moisten with fabric
cleaning fluid and scrape again .
FRUIT STAINS,
COFFEE,LIQUOR,WINE,
SOFT DRINKS, ICE
CREAM AND MILK-Wipe
with cloth soaked in cold water
. If necessary, clean
lightly with fabric
cleaning fluid . Soap and water is
not recommended
as it might set the stain .
CATSUP-Wipe with cloth soaked
in
cool water
.
If further cleaning is necessary, use a detergent
foam
cleaner .
GREASE, OIL, BUTTER,
MARGARINE
AND CRAYON-Scrap off excess with
dull knife .
Use fabric cleaning fluid .
PASTE OR WAX TYPE SHOE POLISH-Light
application of fabric cleaning fluid .
TAR-Remove excess
with dull knife, moisten
with fabric cleaning fluid, scrape
again, rub lightly
with additional cleaner .
BLOOD-Wipe with
clean cloth moistened with
cold water . Use no soap .
URINE-Sponge stain
with lukewarm soap suds
from mild neutral soap on clean cloth, rinse with
cloth soaked
in cold water ; saturate cloth with one
part household
ammonia and five parts water, apply
for one minute,
rinse with clean, wet cloth .
VOMITUS-Sponge with clean cloth dipped in
clean, cold water .
Wash lightly with lukewarm water
and
mild neutral soap . If odor persists, treat area
with a
water-baking soda solution (one teaspoon bak-
ing soda
to one cup of tepid water) . Rub again with
cloth and cold
water . Finally, if necessary, clean
lightly
with
fabric
cleaning fluid .
against vehicle
while
assistant inside
marks points of
leakage, if any exist .

1- 4

BODY
If location of leak has been
determined to be
around
windshield or rear glass, dry surface and ap-
ply rubber
cement . Apply cement to outside, both
between glass and
weatherstrip and between wea-
therstrip and
body .
If the leak is around any side window it will
be
necessary to remove the window and install
a new
seal .
A quick method for locating many air and water
leaks at windshield, backglass, bolt holes, weather-
stripping and joints is as follows :
Aluminum corrodes just as iron and steel rusts .
Under certain conditions aluminum will corrode
more rapidly than steel . Inspect body surfaces
regu-
larly for corrosion and paint condition .
Only sound
parts can be
refinished
. If corrosion
is excessive, replace with new parts . Remove old
parts . Refinish all exposed adjacent parts which re
main on vehicle . When installing new parts use only
zinc or cadmium coated bolts, washers, and nuts .
The
instructions which follow cover both alumi-
num and fiberglass, and both new and old parts .
1 . Through cleaning is essential ; all corrosion,
grease, and other foreign matter must be removed .
Solvent cleaning, pressure steam cleaning, wire
brushing, and hand sanding methods are recom-
mended .
2 . Completely remove old paint by use of organic
solvents . Do not use alkaline paint remover on
aluminum . If old primer is very difficult to remove
and there is
no evidence of metal corrosion, old
primer may be left on, but all loose paint
must be
removed
.
3 . Wipe the entire area to be refinished with
cloths saturated with DuPont No . T-3812 reducer
(or equivalent) . Wipe dry .
4 . Treat any
scratched or abraded areas with Du-
Pont No . VM-5717 metal conditioner (orequivalent)
reduced
one
(1) part by volume with four (4) parts
of water .
PAINTING
Close all windows and vents,
turn
air
condition-
ing or heater blower
motor to
high
position and out-
side air and close
doors . Run water over suspected
leak area in a small controllable stream and observe
area for pressure
bubbles .
Water whichshows
up at a certain place inside
vehicle may actually be entering
at a point other than
where water is found . Back-track path of water to
point of entry . Applybody sealing compound over
all leak points . If
leakage occurs at door opening,
check weatherstrip .
Seal with rubber cement or re-
place if necessary . If door does not firmly
contact
weatherstrip, align door . Refer to "Door
Adjust-
ment" later in this section .
a . Apply the above mixture with a sponge or
brush and allow to stand approximately three (3)
minutes .
b .
Wipe
area with a damp cloth . Dry
thoroughly
.
5 .
Apply
a coat of pre-primer (sometimes called
wash-
primer), preferably by spraying to a uniform
and
complete coverage coat on all surfaces . This type
primer uses
a special accelerating agent containing
phosphoric
acid
which
produces an excellent bond to
metal . AP-10 or A-158
made by M & T Chemical
Co ., XE-5220 made
by Bakelite Corporation, and
818-012 (2 parts), plus T8539 (1
part) made by Du-
Pont, or any equivalent material made by
a reputable
paint manufacturer should be acceptable . These
materials must be used within a few
hours after addi-
tion of accelerator, therefore, directions of manufac-
turer should be observed carefully . Apply
by
spraying . Allow parts to dry .
6 . Use a zinc chromate primer such as DuPont
No . 63-150 or Pontiac Varnish Company's GMT-
434, or any equivalent material made by a reputable
manufacturer . Apply primer, preferably by spraying,
to a minimum thickness
of 0 .5 mils . Allow parts to
dry .
7 . Apply finish coats :
a . For understructure and other parts
not
re-
quiring color, apply a second coat of DuPont No .
63-150
or Pontiac Varnish Company's GMT-434, or
equivelent .
b . To exposed body parts, apply desired color
coats in accordancewith standard practice .