Chrysler RAM TRUCK 2500 1994 Service Manual page 296

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COOLING SYSTEM 7 - 41
Operate tester pump to bring pressure to 104 kPa
(15 psi) on gauge. I f pressure cap fails to hold pres­
sure of at least 97 kPa (14 psi) replace cap. Refer to
C A U T I O N below.
The pressure cap may test properly while posi­
tioned on tool 7700 (or equivalent). I t may not hold
pressure or vacuum when installed on radiator. I f so,
inspect radiator filler neck and cap's top gasket for
damage. Also inspect for dirt or distortion that may
prevent cap from sealing properly.
CAUTION: Tool 7700 is very sensitive to small air
leaks, which will not c a u s e cooling system prob­
lems. A pressure cap that does not have a history
of coolant loss should not be replaced just because
it leaks slowly when tested with this tool. Add water
to tool. Turn tool upside down and recheck pres­
sure cap to confirm that c a p needs replacement.
INSPECTION
Hold cap at eye level, right side up. The vent valve
(Fig. 62) at bottom of cap should open. I f rubber gas­
ket has swollen and prevents vent valve from open­
ing, replace cap.
Hold cap at eye level, upside down. I f any light can
be seen between vent valve and rubber gasket, re­
place cap. Do not use a replacement cap that has
a spring to hold vent shut. A replacement cap
must be the type designed for a coolant reserve/over­
flow system with a completely sealed diaphragm
spring and a rubber gasket. This gasket is used to
seal to radiator filler neck top surface. Use of proper
cap will allow coolant return to radiator.
HAOIATOiS
GENERAL INFORMATION
The radiator used on all engines (both gas powered
and diesel) are of a cross-flow design with horizontal
tubes through the radiator core and vertical side
tanks.
Aluminum cores with plastic side tanks are used
on all 3.9L V-6 and 5.2/5.9L V-8 engines. Copper-
brass cores are used with the 8.0L V-10 and diesel
engines.
The radiator supplies sufficient heat transfer to
cool the engine and automatic transmission (if
equipped).
RADIATOR COOLANT FLOW CHECK
Use the following procedure to determine i f coolant
is flowing through the cooling system.
(1) Idle engine until operating temperature is
reached. I f the upper radiator hose is warm to the
touch, the thermostat is opening and coolant is flow­
ing to the radiator.
WARNING: HOT, P R E S S U R I Z E D C O O L A N T CAN
C A U S E INJURY B Y S C A L D I N G . USING A R A G TO
C O V E R T H E RADIATOR P R E S S U R E CAP, O P E N RA­
DIATOR C A P S L O W L Y TO T H E F I R S T STOP. THIS
WILL A L L O W ANY BUILT-UP P R E S S U R E TO VENT
TO T H E R E S E R V E / O V E R F L O W TANK. A F T E R P R E S ­
S U R E BUILD-UP H A S B E E N R E L E A S E D , R E M O V E
C A P FROM F I L L E R N E C K .
(2) Drain a small amount of coolant from the radi­
ator until the ends of the radiator tubes are visible
through the filler neck. Idle the engine at normal op­
erating temperature. I f coolant is flowing past the ex­
posed tubes, the coolant is circulating.
R A D I A T O R REMOVAL—ALL ENGINES
(1) All Engines Except Diesel: Disconnect nega­
tive battery cable from battery.
Diesel engine: Disconnect both negative battery
cables at both batteries. Remove the nuts retaining
the positive cable to the top of radiator. Position pos­
itive battery cable to rear of vehicle.
WARNING: DO NOT R E M O V E T H E C Y L I N D E R
B L O C K DRAIN P L U G S OR L O O S E N T H E RADIATOR
DRAINCOCK WITH T H E S Y S T E M HOT AND UNDER
P R E S S U R E . S E R I O U S B U R N S FROM C O O L A N T
CAN O C C U R .
(2) Drain the cooling system. Refer to Draining
Cooling System i n this group.
(3) Disconnect throttle cable from clip at top of ra­
diator fan shroud.
HOSE CLAMP HOSE
J9207-36
Fig. 63 Hose Clamp Tool—Typical