Engine Coolant Concentrate

General Motors Engineering Standards. Automotive Engine Coolant, Antifreeze Concentrate-Ethylene Glycol Type, GM 6038-M, Jan. 1971 Automotive Engine Coolant, Concentrate-Ethylene Glycol Type, GM 6043-M, Sept. 1983. 

Testing corrosion inhibiting, engine coolant concentrate ( antifreeze )... 

Laws have been enacted in many states in an attempt to prevent the sale and distribution of deleterious antifreeze products, such as salt solutions or petroleum coolants. Even ethylene glycol engine coolants must be evaluated by testing and comparison of test results with specifications for engine coolant concentrate, such as ASTM D 3306. These tests ensure desired levels of antifreeze coolant concentrate and inhibitor are available to adequately protect cooling systems against freezing, boilover and corrosion (Fig. 2). 

A properly formulated engine coolant concentrate is composed of several essential ingredients, including base fluid, corrosion inhibitors, foam suppressor, dye, and water. 

Consult your owner s manual to ensure that any air eliminators are used properly. Generally, the procedure is to close tightly all drain openings, pour in engine coolant concentrate, then fill with water of good quality to the proper level. Also, fill the coolant recovery system reservoir to the proper level with properly diluted engine coolant (see Fig. 6). (Avoid use of water containing excessive amounts of minerals, impurities, or suspended matter.)... 

Test Method for Corrosion of Cast Aluminum Alloys in Engine Coolants Under Heat-Rejecting Conditions Engine Coolant Information Report Engine Coolant Concentrate... 

The freezing point of the coolant should be monitored for coolants in all types of service. Additionally, maintenance of the corrosion inhibitor levels is requited of the heavy-duty service coolants and the stationary engine coolants. Because corrosion inhibitors and combinations of corrosion inhibitors work most effectively at given concentrations and specific ratios to the other inhibitors, appropriate concentrations must be maintained to maximize corrosion protection. Many manufacturers of coolants for stationary engines, and manufacturers of SCAs, provide an analytical service to monitor the effective inhibitor concentrations in the system periodically. Recommendations can then be made for proper maintenance and inhibitor replenishment. 

Inhibitor concentrations should be checked on a regular basis and losses restored either by appropriate additions of inhibitor, or by complete replacement of the whole fluid-as recommended, for example, with engine coolants. 

Corrosion is effectively controlled by using chemical inhibitor systems which are added to the glycol to make a complete coolant concentrate formulation commonly referred to as permanent engine coolant. 

Most vehicle and engine coolant manufacturers recommend a 50% (vol) concentration be used year round. This concentration is needed to achieve the engine design cooling capacity, to... 

Solutions are addressed specifically and in more detail in Chapter 7. At this point, however, it is useful to have some imderstanding of the quantitative expression of the amount of solute dissolved in a specified amount of solution. In a relative sense, a solution that has comparatively little solute dissolved per unit volume of solution is called a dilute solution, whereas one with an amount of solute of the same order of magnitude as that of the solvent is a concentrated solution. Water saturated with air at 25 °C contains only about 8 milligrams of oxygen dissolved in 1 liter of water this composes a dilute solution of oxygen. A typical engine coolant solution contains about as much ethylene glycol (antifreeze) as it does water, so it is a concentrated solution. A solution that is at equilibrium with excess solute so that it contains the maximum amount of solute that it can dissolve is called a saturated solution. One that can still dissolve more solute is called an unsaturated solution. 

Recent surveys have shown that over-concentration and under-concentration are common sources of cooling system problems. A minimum concentration of 33 1/3% is required to provide minimal corrosion protection. Maximum freeze protection is obtained at 68% by volume. Concentrations over 68% will adversely affect heat transfer, raise freezing point, and may cause inhibitors to precipitate from the coolant when the engine is operating. 

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