SECTION 6K
S 't K
f i n e G o a U r u j, S y d t e m
Inform ation pertinent to truck m od els co v ered by th is supplem ent
is the sam e a s explained in S e r v ic e Manual S T -331-71 ENGINE COOL
ING SYSTEM (SEC. 6K), p ages 6K-1 through 6K -9, ex cep t as indicated
by the follow ing inform ation w hich is eith er new or supplem ental in
nature.
R eferen ce should be m ade to RADIATOR AND SURGE TANK
(SEC. 13) in th is supplem ent fo r inform ation regarding radiator mount
ing, radiator co re and su rge tank and cooling s y s te m fille r cap.
C O O L IN G SYSTEM GENERAL M AIN TEN AN CE
TEST CO O LANT LEVEL
Engine coolant should be checked for proper
le v e l regu larly (daily if n e c e ssa r y , depending on
se v e r ity of se r v ic e ) and every s ix months for c o r
ro sio n and fr e e z e protection to at le a s t -2 0 F ., or
to the low est tem perature expected during the period
of veh icle operation. Each two y e a r s or 24,000
m ile s , w hichever fir s t o cc u r s, cooling s y ste m m ust
b e drained, flushed, and r e fille d with a new coolant
solution.
RADIATOR CORE EXTERIOR
For proper cooling e fficien cy , the ex terio r of
the radiator core and A /C condenser, if so equip
ped, m ust be kept clean. Light brushing and r e
v e r s e a ir flow is usually a sa tisfa c to r y cleaning
m ethod. In se cts can usu ally be rem oved with a
garden hose using light w ater p r e ssu r e .
C O O LIN G SYSTEM PRESSURE CHECK
S everal types of cooling sy ste m p r e ssu r e
checking d ev ices a re available lo ca lly and manu
fa c tu r e r 's in stru ction s should be follow ed for
p rop er u se . A typical te s te r is illu stra ted in figure
1 and p roced u res a re given below for testin g the
p r e s s u r e cap and cooling sy ste m .
1. T esting R adiator Cap
CAUTION: The radiator cap should
not be removed while the engine is at
normal operating temperature. If it is
necessary to remove the cap while the
engine is hot, first relieve the pressure
in the system by turning the radiator cap
counterclockwise to first stop, using cau
tion not to scald hands. Push down on cap
and turn counterclockwise to remove cap.
a. With radiator fille r cap rem oved, wet the
cap gasket with w ater and w ash off any sedim ent
from sea lin g su rfa ce, then in sta ll cap on te s te r .
b. Pump up p r e s s u r e by operating pump plung
er handle. When the p r e ssu r e stam ped on cap is
reached, o b serv e te s te r dial and note the rate of
d e c r e a se in p r e s s u r e .
c. The indicator hand on gauge dial should r e
main within the corresponding p r e s s u r e segm ent
of s c a le for approxim ately 10 seco n d s. If p r e ssu r e
cap does not m eet th is re q u ir e m e n t,it should be
rep laced with new cap.
2. T estin g C ooling System
a.
Tighten a ll radiator andheater h ose clam p s.
A lso , check other connections for leak s at air com
p r e s s o r coolant lin e s , etc.
G A U G E H O SE A N D .T A P
PUMP A N D G A U G E
ASSEMBLY
FILLER NECK1
SON RADIATOR
O VERFLOW HOSE
Figure 1 — Use of C o olin g System Tester (Typical)
