Chrysler RAM TRUCK 2500 1994 Service Manual page 293

7 - 31 COOLING SYSTEM
PRESSURE TESTER METHOD
The engine should be at normal operating temper­
ature. Recheck the system cold i f cause of coolant
loss is not located during the warm engine examina­
tion.
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 .
Carefully remove radiator pressure cap from filler
neck and check coolant level. Push down on cap to
disengage i t from stop tabs. Wipe inside of filler neck
and examine lower inside sealing seat for nicks,
cracks, paint, dirt and solder residue. Inspect radia­
tor-to-reserve/overflow tank hose for internal obstruc­
tions. Insert a wire through the hose to be sure i t is
not obstructed.
Inspect cams on outside of filler neck. I f cams are
bent, seating of pressure cap valve and tester seal
will be affected. Bent cams can be reformed i f done
carefully. Attach pressure tester (7700 or an equiva­
lent) to radiator filler neck (Fig. 58).
C O O L I N G SYSTEM
Fig. 58 Pressure Testing Cooling System—Typical
Operate tester pump to apply 103.4 kPa (15 psi)
pressure to system. I f hoses enlarge excessively or
bulges while testing, replace as necessary. Observe
gauge pointer and determine condition of cooling sys­
tem according to following criteria:
Holds Steady: I f pointer remains steady for two
minutes, serious coolant leaks are not present i n sys­
tem. However, there could be an internal leak that
does not appear with normal system test pressure. I f
i t is certain that coolant is being lost and leaks can­
not be detected, inspect for interior leakage or per­
form Internal Leakage Test.
Drops Slowly: Indicates a small leak or seepage is
occurring. Examine all connections for seepage or
slight leakage with a flashlight. Inspect radiator,
hoses, gasket edges and heater. Seal small leak holes
with a Sealer Lubricant (or equivalent). Repair leak
holes and inspect system again with pressure ap­
plied.
Drops Quickly: Indicates that serious leakage is
occurring. Examine system for external leakage. I f
leaks are not visible, inspect for internal leakage.
Large radiator leak holes should be repaired by a
reputable radiator repair shop.
INTERNAL LEAKAGE INSPECTION
Remove engine oil pan drain plug and drain a
small amount of engine oil. I f coolant is present i n
the pan, i t will drain first because i t is heavier than
oil. A n alternative method is to operate engine for a
short period to churn the oil. After this is done, re­
move engine dipstick and inspect for water globules.
Also inspect transmission dipstick for water globules
and transmission fluid cooler for leakage.
WARNING: WITH P R E S S U R E T E S T E R TOOL 7700
INSTALLED ON RADIATOR, DO NOT ALLOW P R E S ­
S U R E T O E X C E E D 110 KPA (20 PSI). P R E S S U R E
WILL BUILD UP QUICKLY IF A COMBUSTION L E A K
IS P R E S E N T . TO R E L E A S E P R E S S U R E , R O C K
T E S T E R FROM SIDE TO S I D E . WHEN REMOVING
T E S T E R , DO NOT TURN T E S T E R MORE THAN 1/2
TURN IF S Y S T E M IS UNDER P R E S S U R E .
Operate engine without pressure cap on radiator
until thermostat opens. Attach a Pressure Tester to
filler neck. I f pressure builds up quickly i t indicates a
combustion leak exists. This is usually the result of a
cylinder head gasket leak or crack i n engine. Repair
as necessary.
I f there is not an immediate pressure increase,
pump the Pressure Tester. Do this until indicated
pressure is within system range of 110 kPa (16 psi).
Fluctuation of gauge pointer indicates compression or
combustion leakage into cooling system.
Because the vehicle is equipped with a catalytic
converter, do not remove spark plug cables or short
out cylinders (non-diesel engines) to isolate compres­
sion leak.
I f the needle on dial of pressure tester does not
fluctuate, race engine a few times to check for an ab­
normal amount of coolant or steam. This would be
emitting from exhaust pipe. Coolant or steam from
exhaust pipe may indicate a faulty cylinder head gas­
ket, cracked engine cylinder block or cylinder head.
A convenient check for exhaust gas leakage into
cooling system is provided by a commercially avail­
able Block Leak Check tool. Follow manufacturers i n ­
structions when using this product.
COMBUSTION LEAKAGE TEST—WITHOUT
PRESSURE TESTER
DO NOT WASTE reusable coolant. I f solution is
clean, drain coolant into a clean container for reuse.