RAM 2500 Truck 4WD L6-5.9L DSL Turbo VIN 6 (1999)
Coolant: Description and Operation
The cooling system is designed around the coolant. Coolant flows through the engine water jacket absorbing 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
coolant also removes heat from the automatic transmission fluid in vehicles equipped with an automatic transmission.
COOLANT PERFORMANCE
ETHYLENE-GLYCOL MIXTURES
The required ethyleneglycol (antifreeze) and water mixture depends upon the climate and vehicle operating conditions. The recommended mixture of
50/50 ethyleneglycol and water will provide protection against freezing to -37°C 05° F). The antifreeze concentration must always be a minimum of
44 percent, year-round in all climates. If percentage 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 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 percentage of antifreeze can
cause the engine to overheat because the specific heat of antifreeze is lower than that of water.
100 Percent Ethyleneglycol-Should Not Be Used in Chrysler Vehicles
Use of 100 percent ethyleneglycol will cause formation of additive deposits in the system, as the corrosion inhibitive additives in ethyleneglycol
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 temperature can result in engine detonation. In addition, 100 percent ethyleneglycol freezes
at 22°C (-8°F).
Propyleneglycol Formulations-Should Not Be Used in Chrysler Vehicles
Propyleneglycol formulations do not meet Chrysler coolant specifications. It's overall effective temperature range is smaller than that of
ethyleneglycol. The freeze point of 50/50 propyleneglycol and water is -32°C (-26°F). 5°C higher than ethyleneglycol's freeze point. The boiling point
(protection against summer boil-over) of propyleneglycol is 125°C (257°F ) at 96.5 kPa (14 psi), compared to 128°C (263°F) for ethyleneglycol. Use
of propyleneglycol can result in boil-over or freeze-up in Chrysler vehicles, which are designed for ethyleneglycol. Propylene glycol also has poorer
heat transfer characteristics than ethylene glycol. This can increase cylinder head temperatures under certain conditions.
Propyleneglycol/Ethyleneglycol Mixtures-Should Not Be Used in Chrysler Vehicles
Propyleneglycol/Ethyleneglycol Mixtures can cause the destabilization of various corrosion inhibitors, causing damage to the various cooling system
components. Also, once ethyleneglycol and propyleneglycol 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.
CAUTION: Richer antifreeze mixtures cannot be measured with normal field equipment and can cause problems associated with 100 percent
ethyleneglycol.
COOLANT SELECTION-ADDITIVES
The presence of aluminum components in the cooling system requires strict corrosion protection. Maintain coolant at specified level with a mixture of
ethyleneglycol based antifreeze and water. Only use an antifreeze containing ALUGARD 340 - 2mm 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.
