Chapter 20 - Coolant Flashcards
Coolant composed of:
47% ethylene glycol
50% water
3% Additives
Ethylene Glycol-based Coolant
Contains ethylene glycol but does not contain silicates or phosphates. Usually orange in color
Organic Acid Technology (OAT)
A variation to OAT coolant in that it uses carboxylates (organic acid salts) yet provide the correct PH
Hybrid Organic Acid Technology (HOAT)
Conventional coolant used for over 50 years. Generally green in color and contains inorganic salts such as sodium silicate, phosphates, and borates. Silicates have been found to be erosive to water pump impellers
Inorganic Additive Technology
Causes scaling and reduces heat transferability of coolant
pH too high, or alkaline
Causes corrosion of engine components exposed to coolant
pH too low, or acidic
Coolant with a small amount of substance added to make it taste bitter
Embittered Coolant
Usually a HOAT, with extended life and a low-silicate, phosphate-free coolant
Universal Coolant
Boiling point of water
212°F/100°C
Freezing point of water
32°F/0°C
Freezing point of 50/50 antifreeze
-34°F/-37°C
Amount boiling point is increased per 1 PSI pressure
3°F
Ideal freezing point and boiling point of coolant (including pressure cap)
Below -20°F and above 234°F
Standard coolant pH
IAT: 7.5 - 10
OAT, HOAT, and PHOAT: <7.5
Flow of electrical current as a result of two different metals in a liquid (like a battery). Requires no outside voltage source
Galvanic Activity
Chemical decomposition requiring the use of an outside voltage source
Electrolysis
Coolant replacement intervals
OAT/HOAT: 5 years or 150k miles
Japanese Vehicles: 3 years or 36k miles
IAT: 2 years or 24k miles
Chemical reaction that takes place between coolant additives and the metal it protects, forming a barrier between coolant and engine metal. Reason for recommendation to not change coolant types
Passivation
