COOLING SYSTEM - TESTING FOR LEAKS
ULTRAVIOLET LIGHT METHOD
A leak detection additive is available through the parts
department that can be added to cooling system. The
additive is highly visible under ultraviolet light (black
light) (1). Pour one ounce of additive into cooling sys-
tem. Place heater control unit in HEAT position. Start
and operate engine until the radiator upper hose is
warm to touch. Aim the commercially available black
light tool at components to be checked. If leaks are
present, black light will cause the additive to glow a
bright green color.
The black light can be used in conjunction with a pres-
sure tester to determine if any external leaks exist.
PRESSURE TESTER METHOD
The engine should be at normal operating tempera-
ture. Recheck the system cold if the cause of coolant
loss is not located during the warm engine examina-
tion.
WARNING: HOT, PRESSURIZED COOLANT CAN
CAUSE INJURY BY SCALDING.
Carefully remove the radiator pressure cap from the
filler neck and check coolant level. Push down on cap
to disengage it from the stop tabs. Wipe the inside of
filler neck and examine the lower inside sealing seat
for nicks, cracks, paint, dirt and solder residue. Inspect
the radiator-to- reserve/overflow tank hose for internal
obstructions. Insert a wire through the hose to be sure
it is not obstructed.
Inspect cams on the outside of filler neck. If the cams
are damaged, seating of the pressure cap valve and
tester seal will be affected.
Attach pressure tester (7700 or an equivalent) to radi-
ator filler neck (1).
Operate tester pump to apply 103.4 kPa (15 psi) pres-
sure to system. If hoses enlarge excessively or bulge while testing, replace as necessary. Observe the gauge
pointer and determine the condition of the cooling system according to the following criteria:
Holds Steady: If the pointer remains steady for two minutes, serious coolant leaks are not present in system. How-
ever, there could be an internal leak that does not appear with normal system test pressure. If it is certain that
coolant is being lost and leaks cannot be detected, inspect for interior leakage or perform Internal Leakage Test.
Refer to INTERNAL LEAKAGE INSPECTION .
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COOLING
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