Dodge RAM TRUCK 1500 1995 Service Manual page 307

BR
COOLING SYSTEM SERVICE PROCEDURES 7 - 37
LIFT
OUTER
SEAL S H O U L D E R
J9507-23
Fig. 53 Thermostat Seals—5.9L Diesel—Typical
(5) Position- generator to thermostat housing. In­
stall and tighten mounting bolt to 24 N-m torque.
Tighten pivot bolt to 43 N-m (32 ft. lbs.) torque.
(6) Install the check valve hose and hose clamp at
thermostat housing (Fig. 51).
(7) Install accessory drive belt. Refer to Belt Re­
moval/Installation in the Engine Accessory Drive Belt
section of this group.
(8) Connect negative battery cables to both batter­
ies.
(9) Fill cooling system and check for leaks. Refer to
Refilling' Cooling System in this group.
COOLANT •
GENERAL INFORMATION
The cooling system is designed around the coolant.
Coolant flows through the engine water jacket ab­
sorbing heat produced during engine operation. The
coolant carries the heat to radiator and heater core.
Here it is transferred to the ambient air passing
through the radiator and heater core fins. The cool­
ant also removes heat from the automatic transmis­
sion fluid in vehicles equipped with an automatic
transmission.
COOLANT PERFORMANCE
The required ethylene-glycol (antifreeze) and water
mixture depends upon climate and vehicle operating
conditions. The coolant performance of various mix­
tures follows:
Pure Water-Water can absorb more heat than a
mixture of water and ethylene-glycol. This is for pur­
pose of heat transfer only. Water also freezes at a
higher temperature and allows corrosion.
100% Ethylene-Glycol-The corrosion inhibiting
additives in ethylene-glycol need the presence of wa­
ter to dissolve. Without water, additives form depos­
its in system. These act as insulation causing
temperature to rise to as high as 149°C (300°F). This
temperature is hot enough to melt plastic and soften
solder. The increased temperature can result in en­
gine detonation. In addition, 100 percent ethylene-
glycol freezes at -22°C (-8°F).
50/50 Ethylene-Glycol and Water-Is the recom­
mended mixture, it provides protection against freez­
ing to -37°C (-35°F). The antifreeze concentration
must always be a minimum of 44 percent, year-
round in all climates. If percentage is lower, engine
parts may be eroded by cavitation. Maximum protec­
tion against freezing is provided with a 68 percent
antifreeze concentration, which prevents freezing
down to -67.7°C (-90°F). A higher percentage will
freeze at a warmer temperature. Also, a higher per­
centage of antifreeze can cause the engine to over­
heat because specific heat of antifreeze is lower than
that of water.
CAUTION: Richer antifreeze mixtures cannot be
measured with normal field equipment and can
cause problems associated with 100 percent ethyl­
ene-glycol.
COOLANT SELECTION-ADDITIVES *
The presence of aluminum components in the cool­
ing system requires strict corrosion protection. Main­
tain coolant at specified level with a mixture of
ethylene-glycol based antifreeze and water. Only use
an antifreeze containing ALUGARD 340-2 ™ such as
Mopar Antifreeze. If coolant becomes contaminated
or looses color, drain and flush cooling system and fill
with correctly mixed solution.
CAUTION: Do not use coolant additives that are
claimed to improve engine cooling.
COOLANT SERVICE—EXCEPT DIESEL
It is recommended that the cooling system be
drained and flushed at 84,000 kilometers (52,500
miles) or 3 years, whichever occurs first. Then every
two years or 48,000 kilometers (30,000 miles), which­
ever occurs first.
COOLANT SERVICE—DIESEL ENGINE
It is recommended that the cooling system be
drained and flushed every 24 months or 38,600 kilo­
meters (24,000 miles), whichever occurs first.
COOLANT LEVEL CHECK—ROUTINE
Do not remove radiator cap for routine cool­
ant level inspections. The coolant level can be
checked at the coolant reserve/overflow tank.
The coolant reserve/overflow system provides a
quick visual method for determining the coolant level
without removing the radiator pressure cap. With en­
gine idling and at normal operating temperature, ob-