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GMC X-7425 1973 Maintenance Manual page 20

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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 (or equivalent)
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 which shows 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. Apply body 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 accordance with standard practice .

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