GMC 4000 Series Service Manual page 547

Sec. 13
Page 536
RADIATOR A N D SURGE TANK
6. Check filler cap seals for evidence of
cracking or separation. Replace as required.
To assist in maintaining efficient heat d issi­
pation, an occasional external flushing with water
will remove majority of dirt accumulation and
foreign matter from between core fins. Water under
moderate pressure should be directed from behind
core to force debris out in opposite direction of its
entrance. Water should be directed in line with
fins, not sideways, to reduce possibility of bending
fins.
When coolant loss is evident or engine over­
heating occurs, the damaged or clogged radiator
should be serviced by a radiator specialist or re­
placed with a new one. Efficient repair of radiators
requires the use of special tools and equipment as
well as provisions for making proper tests. If rad­
iator core requires painting, spray with special
radiator paint; do not use paint mixed with oil, as
oil mixed paint will form an insulation and prevent
efficient dissipation of heat.
RADIATOR MOUNTINGS
All radiator core mountings consist of three
major components; upper tank, center core section,
and lower tank. All "L" models employ a separate
bracket mounted surge tank which serves as a
coolant reservoir for the radiator core.
Type of radiator core mounting varies ac­
cording to model and engine type. All "E" and "S"
model radiator assem blies are equipped with side
flanges which are mounted flush against radiator
shell and fastened into position with mounting bolts
(fig. 1). On "L" models, the radiator is supported
by upper and lower mountings (fig. 2). Radiator on
"P" models rest on a lower support and is retained
at sides by radiator flanges bolted to side supports
(fig. 3). Also, an upper cross bar is used to add
stability to side supports.
Figure 1— Radiator M o u n tin g ("E " a n d "S " M od els)
G M C S E R V I C E M A N U A L
r-RONT
V IE W AT A R R O W "A "
T -5 7 8 2
RADIATOR REPLACEMENT
Due to various types of radiator mountings,
the following general information applies to all
models. The radiator assembly may include a fan
shroud and an oil cooler at base of radiator core.
If equipped with a fan shroud, remove attaching
bolts and then lay shroud back over fan blade. When
oil lines are removed, make provisions for catch­
ing oil drainage from cooler tank and lines. Do not
re-u se this oil. Replenish transmission to recom ­
mended level with fresh fluid after installing rad­
iator.
Some models may be equipped with a separate
power steering oil cooler which is attached in front
of radiator core by means of cooler support braces.
On models so equipped, it may be necessary to
remove power steering oil cooler in order to re­
place radiator core. For information relative to
removal and installation of oil cooler, see "POWER
STEERING" (SEC. 9B) of this manual.
"E" AND "S" MODELS (Fig. 1)
Removal
1. Drain radiator.
2. Remove hood assembly as instructed under
"Hood Assembly Replacement" in SHEET METAL
(SEC. 11) of this manual.
3. Remove fan shroud (if equipped) and p osi­
tion it back over fan.
4. Remove coolant hoses and transm ission oil
lines (if equipped).
5. Support radiator safely in position and re­
move radiator mounting bolts.
6. Carefully lift radiator up and out of vehicle.
Installation
1. Lower radiator into position against rad­
iator shell. Install radiator mounting bolts. Tighten
bolts to 10 to 15 foot-pounds torque.
2. Connect coolant hoses and oil lines.
3. Install fan shroud (if equipped).
4. Install hood assembly as instructed under
"Hood Assembly Replacement" in SHEET METAL
(SEC. 11) of this manual.
5. Fill cooling system and transm ission to
proper level.
6. Start engine and inspect system for leaks.
"L" MODELS (Fig. 2)
Removal
1. Drain radiator.
2. Disconnect throttle linkage at linkage brac­
ket on radiator support.
3. Remove electrical components from rad­
iator support assembly.