Wrangler 4WD L4-150 2.5L VIN P MFI (1998)
Coolant: Description and Operation
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 percentage 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 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 problems associated with 100 percent
ethylene-glycol.
