Dodge Ram Truck 1500-2500-3500. Manual — part 233

WARNING: ANTIFREEZE IS AN ETHYLENE GLYCOL BASE COOLANT AND IS HARMFUL IF SWALLOWED OR
INHALED. IF SWALLOWED, DRINK TWO GLASSES OF WATER AND INDUCE VOMITING. IF INHALED, MOVE
TO FRESH AIR AREA. SEEK MEDICAL ATTENTION IMMEDIATELY. DO NOT STORE IN OPEN OR UNMARKED
CONTAINERS. WASH SKIN AND CLOTHING THOROUGHLY AFTER COMING IN CONTACT WITH ETHYLENE
GLYCOL. KEEP OUT OF REACH OF CHILDREN. DISPOSE OF GLYCOL BASE COOLANT PROPERLY, CON-
TACT YOUR DEALER OR GOVERNMENT AGENCY FOR LOCATION OF COLLECTION CENTER IN YOUR
AREA. DO NOT OPEN A COOLING SYSTEM WHEN THE ENGINE IS AT OPERATING TEMPERATURE OR HOT
UNDER PRESSURE, PERSONAL INJURY CAN RESULT. AVOID RADIATOR COOLING FAN WHEN ENGINE
COMPARTMENT RELATED SERVICE IS PERFORMED, PERSONAL INJURY CAN RESULT.

ETHYLENE-GLYCOL MIXTURES

CAUTION: Richer antifreeze mixtures cannot be measured with normal field equipment and can cause prob-
lems associated with 100 percent ethylene-glycol.

The use of aluminum cylinder blocks, cylinder heads and water pumps requires special corrosion protection. Only
Mopar

Antifreeze/Coolant, 5 year/100,000 Mile Formula (ethylene-glycol base coolant 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 operating condi-
tions. The antifreeze concentration must always be a minimum of 44 percent, year-round in all climates. If per-
centage is lower than 44 percent, engine parts may be eroded by cavitation, and cooling system
components may be severely damaged by corrosion. Maximum protection against freezing is provided with a
68% antifreeze 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 the spe-
cific heat of antifreeze is lower than that of water.

Use of 100 percent ethylene-glycol will cause formation of additive deposits in the system, as the corrosion inhibitive
additives in ethylene-glycol require the presence of water to dissolve. The deposits act as insulation, causing tem-
peratures 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 engine detonation. In addition, 100 percent ethylene-glycol freezes at 22°C
(-8°F ).

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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 higher than ethylene-glycol’s freeze point. The boiling point (protection
against summer boil-over) of propylene-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. Propylene glycol also has poorer heat transfer characteristics than ethylene glycol. This can
increase cylinder head temperatures under certain conditions.

Propylene-glycol/ethylene-glycol Mixtures can cause the destabilization of various corrosion inhibitors, causing dam-
age to the various cooling system components. Also, once ethylene-glycol and propylene-glycol based coolants are
mixed in the vehicle, conventional methods of determining freeze point will not be accurate. Both the refractive index
and specific gravity differ between ethylene glycol and propylene glycol.

HOAT COOLANT

WARNING: ANTIFREEZE IS AN ETHYLENE-GLYCOL BASE COOLANT AND IS HARMFUL IF SWALLOWED OR
INHALED. IF SWALLOWED, DRINK TWO GLASSES OF WATER AND INDUCE VOMITING. IF INHALED, MOVE
TO FRESH AIR AREA. SEEK MEDICAL ATTENTION IMMEDIATELY. DO NOT STORE IN OPEN OR UNMARKED
CONTAINERS. WASH SKIN AND CLOTHING THOROUGHLY AFTER COMING IN CONTACT WITH ETHYLENE-
GLYCOL. KEEP OUT OF REACH OF CHILDREN. DISPOSE OF GLYCOL BASE COOLANT PROPERLY, CON-
TACT YOUR DEALER OR GOVERNMENT AGENCY FOR LOCATION OF COLLECTION CENTER IN YOUR
AREA. DO NOT OPEN A COOLING SYSTEM WHEN THE ENGINE IS AT OPERATING TEMPERATURE OR HOT
UNDER PRESSURE, PERSONAL INJURY CAN RESULT. AVOID RADIATOR COOLING FAN WHEN ENGINE
COMPARTMENT RELATED SERVICE IS PERFORMED, PERSONAL INJURY CAN RESULT.

CAUTION: Use of Propylene-Glycol based coolants is not recommended, as they provide less freeze pro-
tection and less corrosion protection.

The cooling system is designed around the coolant. The coolant must accept heat from engine metal, in the cylinder
head area near the exhaust valves and engine block. Then coolant carries the heat to the radiator where the tube/
fin radiator can transfer the heat to the air.

The use of aluminum cylinder blocks, cylinder heads, and water pumps requires special corrosion protection.
Mopar

Antifreeze/Coolant, 5 Year/100,000 Mile Formula (MS-9769), or the equivalent ethylene-glycol base coolant

with organic corrosion inhibitors (called HOAT, for Hybrid Organic Additive Technology) is recommended. This cool-
ant offers the best engine cooling without corrosion when mixed with 50% ethylene-glycol and 50% distilled water to
obtain a freeze point of -37°C (-35°F). If it loses color or becomes contaminated, drain, flush, and replace with fresh
properly mixed coolant solution.

CAUTION: Mopar

Antifreeze/Coolant, 5 Year/100,000 Mile Formula (MS-9769) may not be mixed with any

other type of antifreeze. Mixing of coolants other than specified (non-HOAT or other HOAT), may result in
engine damage that may not be covered under the new vehicle warranty, and decreased corrosion protec-
tion.

COOLANT PERFORMANCE

The required ethylene-glycol (antifreeze) and water mixture depends upon climate and vehicle operating conditions.
The coolant performance of various mixtures follows:

Pure Water- Water can absorb more heat than a mixture of water and ethylene-glycol. This is for purpose of heat
transfer only. Water also freezes at a higher temperature and allows corrosion.

100 percent Ethylene-Glycol - The corrosion inhibiting additives in ethylene-glycol need the presence of water to
dissolve. Without water, additives form deposits 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 engine detonation. In addition, 100 percent ethylene-glycol freezes at -22°C (-8°F).

50/50 Ethylene-Glycol and Water - Is the recommended mixture, it provides protection against freezing to -37°C
(-34°F). The antifreeze concentration must always be a minimum of 44 percent, year-round in all climates. If per-
centage is lower, engine parts may be eroded by cavitation. Maximum protection against freezing is provided with a
68 percent antifreeze concentration, which prevents freezing down to -67.7°C (-90°F). A higher percentage will

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ENGINE

DR/DH

freeze at a warmer temperature. Also, a higher percentage of antifreeze can cause the engine to overheat 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 prob-
lems associated with 100 percent ethylene-glycol.

COOLANT SELECTION AND ADDITIVES

The use of aluminum cylinder blocks, cylinder heads and water pumps requires special corrosion protection. Only
Mopar

Antifreeze/Coolant, 5 Year/100,000 Mile Formula (glycol base coolant with corrosion inhibitors called HOAT,

for Hybrid Organic Additive Technology) is recommended. This coolant offers the best engine cooling without cor-
rosion when mixed with 50% distilled water to obtain to obtain a freeze point of -37°C (-35°F). If it loses color or
becomes contaminated, drain, flush, and replace with fresh properly mixed coolant solution.

CAUTION: Do not use coolant additives that are claimed to improve engine cooling.

OPERATION

Coolant flows through the engine block absorbing the heat from the engine, then flows to the radiator where the
cooling fins in the radiator transfers the heat from the coolant to the atmosphere. During cold weather the ethylene-
glycol or propylene-glycol coolant prevents water present in the cooling system from freezing within temperatures
indicated by mixture ratio of coolant to water.

DIAGNOSIS AND TESTING

COOLANT CONCENTRATION TESTING

Coolant concentration should be checked when any additional coolant was added to system or after a coolant drain,
flush and refill. The coolant mixture offers optimum engine cooling and protection against corrosion when mixed to
a freeze point of -37°C (-34°F) to -46°C (-50°F). The use of a hydrometer or a refractometer can be used to test
coolant concentration.

A hydrometer will test the amount of glycol in a mixture by measuring the specific gravity of the mixture. The higher
the concentration of ethylene glycol, the larger the number of balls that will float, and higher the freeze protection
(up to a maximum of 60% by volume glycol).

A refractometer Tool 8286 (Refer to 7 - COOLING - SPECIAL TOOLS) will test the amount of glycol in a coolant
mixture by measuring the amount a beam of light bends as it passes through the fluid.

Some coolant manufactures use other types of glycols into their coolant formulations. Propylene glycol is the most
common new coolant. However, propylene glycol based coolants do not provide the same freezing protection and
corrosion protection and is not recommended.

CAUTION: Do not mix types of coolant - corrosion protection will be severely reduced.

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Dodge Ram Truck 1500-2500-3500. Manual — part 233

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