RAM 2500 Truck 2WD L6-5.9L DSL Turbo VIN 7 (2001)
Coolant: Description and Operation
DESCRIPTION
ETHYLENE GLYCOL MIXTURES
CAUTION: Richer antifreeze mixtures cannot be measured with normal field equipment and can cause problems associated with 100 percent
ethylene-glycol.
The required ethylene glycol (antifreeze) and water mixture depends upon the climate and vehicle operating conditions. The recommended mixture of
50/50 ethylene glycol and water will provide protection against freezing to 37°C (0.5°F). The anti freeze 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 (0.0°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.
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 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 ethylene glycol
freezes at 22°C (0.°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 (0.6°F). 5
°C higher than ethylene glycol's freeze point.
The boiling point(protection against summer boil over) of propylene glycol is 125°C (0.57°F) at 96.5 kPa (0.4 psi), compared to 128°C (0.63°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 damage 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.
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 coolant prevents water present in the cooling system from
freezing within temperatures indicated by mixture ratio of coolant to water.
