Q1: Which engine coolants are water-based?
A1: All commercially available engine coolants, except Evans coolants, are water-based.
Q2: What is good about water in a coolant?
A2: Water is cheap. Water in the liquid state has excellent thermal conductivity characteristics.
Q3: What is bad about water in a coolant?
A3: The boiling point of water is too low. There is very little separation between the operating temperature of the coolant and the boiling point of water for the pressure of the system. The boiling point of water is the failure temperature of the cooling system. Water vapor has almost no thermal conductivity. Water is aggressive toward cooling system metals and promotes electrolysis between dissimilar metals within the cooling system.
Q4: Water-based coolant is mostly 50% glycol and 50% water. Why isn’t the failure temperature the boiling point of the mixture, rather than the boiling point of water?
A4: Some locations within the cylinder head generate so much heat that some of the nearby coolant boils. When local coolant boils, the resulting vapor is nearly 100% water vapor. If the coolant that is surrounding the water vapor is above the boiling point of water, the water vapor cannot condense. Under this condition, the water vapor makes an insulating barrier between hot metal and liquid coolant, causing the temperature of the metal to spike to high levels.
Q5: Why is the vapor from boiling a 50/50 glycol/water mixture (EGW) nearly 100% water vapor?
A5: When the mixture is boiled the water part is fractionally distilled, as it is far more volatile than the glycol portion. Water vapor is liberated while the glycol remains in the solution.
Q6: What are various boiling points of interest?
A6: Water at sea level (1 atm. absolute) boils at 100°C. Water at sea level with a 1 atm. pressure cap (2 atm total) boils at 121.1°C. EGW at sea level (1 atm. absolute) boils at 106.6°C. EGW at sea level with a 1 atm. pressure cap (2 atm. total) boils at 128.3°C. Evans Waterless Coolant at sea level (1 atm. absolute) boils at 190.6°C.
Q7: What happens to the boiling points at higher elevations?
A7: The boiling points decline as the altitude increases. Water at 5000 ft. (0.83 atm. absolute) boils at 97.2°C. EGW at 5000 ft. (0.83 atm. absolute) boils at 103.3°C. Evans Coolant at 5000 ft. (0.83 atm. absolute) boils at 186.6°C.
Q8: What is pump cavitation and how can it occur?
A8: Action of the coolant pump creates a low pressure area at the pump inlet. Pump cavitation occurs when coolant near its boiling point encounters the low pressure area and flash vaporizes within the pump. The gas pocket in the pump causes the pump to stop functioning and coolant circulation to stop. Coolant pump cavitation leads directly to catastrophic cooling system failure with the coolant being expelled from the system as steam pressure exceeds the pressure relief setting of the cap.
Q9: What is after-boil?
A9: After-boil occurs after shut-down of a stressed engine when the coolant is near its boiling point and residual heat remains in the cylinder head or in an auxiliary circuit such as an EGR cooler. Upon shut-down the coolant pump ceases to circulate coolant through the cooling system. Residual heat boils the stagnant coolant, making steam pressure that exceeds the pressure relief setting of the cap. Coolant is pushed out of the system.
Q10: What is the primary purpose of an engine cooling system?
A10: To keep engine metal temperatures under control.
Q11: What burden must be uniquely borne by a functioning cooling system using any water-based coolant?
A11: The cooling system must keep the coolant below the boiling point of water for the pressure of the system under all operating conditions and after shut-down. This task is difficult because the coolant frequently operates close to the boiling point of water.
Q12: What is the most important operational feature of Evans Waterless Coolant?
A12: The huge separation between the operating temperature and the boiling point of the coolant, on the order of at least 37.7°C.
Q13: What is the Reserve Capacity made available by changing to Evans Waterless Coolant?
A13: The huge separation between the operating temperature and the boiling point of Evans Waterless Coolant unlocks a Reserve Capacity that already exists in systems designed for water-based coolants. Any cooling system designed to keep coolant below the boiling point of water for the pressure of the system under all operating conditions and after shut-down is liberated from those requirements with Evans Waterless Coolant. When temperatures happen to be higher, there are no failures due to the lower boiling point of water. In a 37.7°C environment a radiator that is 121°C will dissipate 25% more heat than one at 104°C.
Q14: Is Evans advocating operating engines at substantially higher temperatures?
A14: Not really. Operating temperatures are normally only slightly warmer than those of water-based coolant. When the engine is stressed and temperatures rise, the cooling system can accommodate that increase in temperature without cooling system failures.
Q15: How does Evans Waterless Coolant prevent engine hot spots?
A15: The huge separation between the operating temperature and the boiling point of Evans provides an environment where any locally generated coolant vapor immediately condenses into adjacent liquid coolant. Vapor cannot build into an insulating barrier, and contact between hot metal and liquid coolant is maintained at all times. Metal temperatures are under control at all times.
Q16: How does Evans Waterless Coolant prevent after-boil?
A16: After shut-down, the huge separation between the operating temperature and the boiling point of Evans Coolant, has the capacity to absorb heat from hot metal parts of the cylinder head. Boiling is avoided and there is no build-up of pressure to force coolant out of the system. Stresses on cylinder heads and EGR heat exchangers are avoided as metal temperatures are kept under control.
Q17: How does Evans Waterless Coolant prevent pump cavitation?
A17: The low pressure area of the coolant pump is never at a low enough pressure to flash vaporize. The pump never gets vapor bound and has the capability to pump coolant over a broad range of temperatures.
Q18: How does Evans Waterless Coolant prevent cylinder liner cavitation erosion?
A18: Cylinder liner cavitation erosion is a problem in water-based coolant systems. As the piston moves inside the cylinder there is vibration of the liner. The vibration of the liner against the coolant alternately makes low and high pressures. During the low pressure instant, vapor is created by flash vaporization. During the adjacent high pressure instant, the vapor collapses against the cylinder liner. This repeated action causes an attack against the metal liner, resulting in cavitation erosion.
Q19: How does Evans Waterless Coolant save fuel?
A19: In spark ignition engines Evans Waterless Coolant saves fuel by better control of metal temperatures and the avoidance of hot spots. The consequent reduction of knock permits more efficient spark settings on engines having electronic controls with knock sensing inputs. In heavy duty engines having on-off fan clutches, the “on” temperature can be increased to 110°C, keeping the fan off a large percentage of the time and reducing a significant source of parasitic drag.
Q20: How long will Evans Waterless Coolant and its additives last?
A20: Evans Waterless Coolant will last the life of the engine as long as it is not contaminated with water.
Q21: How do the additives in Evans Waterless Coolant remain in solution without the presence of water?
A21: Evans Waterless Coolant contains no additive that requires water to dissolve or to enable the additive to function.
Q22: How much water is acceptable after a conversion to Evans Waterless Coolant?
A22: In heavy duty diesel applications the water content must not exceed 3.0%. Dry engine installation of Evans Waterless Coolant is preferred.
Q23: Evans Waterless Coolant contains a blend of glycols, including ethylene glycol, which is toxic. How toxic is Evans Waterless Coolant?
A23: Evans Waterless Coolant inhibits the metabolism of ethylene glycol, preventing its toxic metabolites from forming. In tests on rats according to EPA regulations, no rats died eating Evans Waterless Coolant, even in quantities that completely filled the stomachs of the rats, indicating a very low oral toxicity.
Q24: If Evans Waterless Coolant is low in oral toxicity, why is there an ethylene glycol warning on the bottle?
A24: The U.S. Consumer Products Safety Commission requires the ethylene glycol warning on all products that contain over 10 percent ethylene glycol. Permission to waive the labeling requirement requires tests on human tissue that have not yet been performed.