Dodge RAM 1500 1998 Owner's Manual page 346

DR
DIAGNOSIS AND TESTING - RADIATOR
CAP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . 59
WATER PUMP - 3.7L/4.7L
DESCRIPTION
DESCRIPTION - WATER PUMP
DESCRIPTION - WATER PUMP BYPASS . . . . 59
OPERATION
OPERATION—WATER PUMP
OPERATION - WATER PUMP BYPASS
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
INSPECTION . . . . . . . . . . . . . . . . . . . . . . . . . . 61
INSTALLATION . . . . . . . . . . . . . . . . . . . . . . . . . 61
WATER PUMP - 5.9L DIESEL
DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . 62
COOLANT
DESCRIPTION
DESCRIPTION - ENGINE COOLANT
ETHYLENE-GLYCOL MIXTURES
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl-
ene-glycol.
The use of aluminum cylinder blocks, cylinder
heads and water pumps requires special corrosion
protection. Only Mopar
year/100,000 Mile Formula (ethylene-glycol base cool-
ant with corrosion inhibitors called HOAT, for Hybrid
Additive Technology) is recommended. This coolant
offers the best engine cooling without corrosion when
mixed with 50% distilled water to obtain a freeze
point of -37°C (-35°F).
The required ethylene-glycol (antifreeze) and water
mixture depends upon the climate and vehicle oper-
ating conditions. The antifreeze concentration must
always be a minimum of 44 percent, year-round in
all climates. If percentage is lower than 44 per-
cent, engine parts may be eroded by cavitation,
and cooling system
severely damaged by corrosion. Maximum protec-
tion against freezing is provided with a 68% anti-
freeze concentration, which prevents freezing down to
-67.7° C (-90° F). A higher percentage will freeze at a
warmer temperature. Also, a higher percentage of
antifreeze can cause the engine to overheat because
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. . . . . . . . . . . . 60
. . . . . 60
Antifreeze/Coolant,
components may
OPERATION
DIAGNOSIS AND TESTING—WATER PUMP
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
INSPECTION
INSTALLATION
WATER PUMP - 5.7L
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
INSTALLATION
WATER PUMP - 8.0L
DIAGNOSIS AND TESTING - WATER PUMP
REMOVAL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
CLEANING . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
INSPECTION
INSTALLATION
the specific heat of antifreeze is lower than that of
water.
Use of 100 percent ethylene-glycol will cause for-
mation of additive deposits in the system, as the cor-
rosion inhibitive additives in ethylene-glycol require
the presence of water to dissolve. The deposits act as
insulation, causing temperatures to rise to as high as
149° C (300° F). This temperature is hot enough to
melt plastic and soften solder. The increased temper-
ature can result in engine detonation. In addition,
100 percent ethylene-glycol freezes at 22° C (-8° F ).
PROPYLENE-GLYCOL MIXTURES
It's overall effective temperature range is smaller
than that of ethylene-glycol. The freeze point of 50/50
propylene-glycol and water is -32° C (-26° F). 5° C
5
higher than ethylene-glycol's freeze point. The boiling
point (protection against summer boil-over) of propy-
lene-glycol is 125° C (257° F ) at 96.5 kPa (14 psi),
compared to 128° C (263° F) for ethylene-glycol. Use
of propylene-glycol can result in boil-over or freeze-up
on a cooling system designed for ethylene-glycol. Pro-
pylene glycol also has poorer heat transfer character-
istics than ethylene glycol. This can increase cylinder
head temperatures under certain conditions.
Propylene-glycol/ethylene-glycol
cause the destabilization of various corrosion inhibi-
tors, causing damage to the various cooling system
components. Also, once ethylene-glycol and propy-
be
lene-glycol based coolants are mixed in the vehicle,
conventional methods of determining freeze point will
not be accurate. Both the refractive index and spe-
cific gravity differ between ethylene glycol and propy-
lene glycol.
ENGINE
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. . . . . . . . . . . . . . . . . . . . . . . . . 62
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. . . . . . . . . . . . . . . . . . . . . . . . . . 66
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Mixtures
7 - 31
. . . 62
. . . 63
can