Chrysler RAM TRUCK 2500 1994 Service Manual page 268

COOLING SYSTEM 7 - 13
COOLING SYSTEM DIAGNOSIS—DIESEL-CONTINUED
C O N D I T I O N AND CHECKS D I A G N O S I S
TEMPERATURE G A U G E IS INCONSISTENT,
CYCLES A N DIOR IS ERRATICs
(1) Is cycle normal?
(2) Is coolant in radiator low (air will build up in the cooling
system and cause the thermostat to open late)?
(3) Is a cylinder head gasket leak allowing exhaust gas to
enter cooling system (exhaust gas building up in the
cooling system will cause the thermostat to open late)?
(4) Water pump impeller loose on shaft. Loose accessory
drive belt.
(5) Air leak on the suction side of the water pump (allows
air to build up in cooling system causing thermostat to
open late).
(1) a —The gauge pointer may move up and down within
the normal range. This is the raction to the cycles of
the thermostat.
b —The gauge pointer may move to the high end of the
normal range. This is due to heavy use or after an
engine shutdown and restart.
(2) Fill system, vent trapped air and check for leaks.
(3) a —Test for leaking cylinder head gasket leak with a
commercially available Block Leak Tester,
b —Check for coolant in engine oil
c — Inspect for white steam from exhaust system.
(4) Repair or replace as necessary.
(5) Find leak and repair.
J9407-5