Purpose
To measure the foaming tendency and foam-breaking time of engine coolants. Excessive foam can cause cavitation, overflow, and poor heat transfer.

Principle
A specified volume of coolant is aerated at a controlled flow rate (e.g., 100 mL/min) for a set time (usually 5 min) at a fixed temperature (e.g., 25°C or 88°C). The foam volume immediately after aeration is recorded (foaming tendency). Then the time for foam to collapse to a low level (e.g., 0.5 cm of foam) is measured (foam-breaking time). The test may also be run on used or diluted coolants.

Purpose
To determine the density (mass per unit volume) of engine coolant concentrates and diluted coolants. Density relates to freeze point, glycol content, and conformity of the product.

Principle
A hydrometer is floated in a temperature-controlled sample (typically at 20°C or 25°C). The hydrometer reading is taken at the point where the liquid surface intersects the scale. Alternatively, a digital density meter can be used (oscillating U-tube principle). Results are corrected to a reference temperature.

Purpose
To evaluate the corrosion-inhibiting properties of engine coolants on six common metals: copper, solder, brass, steel, cast iron, and aluminum.

Principle
Pre-weighed metal specimens are fully immersed in the coolant (diluted with corrosive water, e.g., 100 ppm Cl⁻, 100 ppm SO₄²⁻) and heated at 88°C ± 2°C for 336 hours (14 days). After the test, specimens are cleaned, reweighed, and the weight loss is calculated. Visual corrosion pitting and changes in coolant appearance, pH, and metal surface condition are also noted.

Purpose
To measure the equilibrium boiling point of engine coolants under atmospheric pressure, indicating the coolant’s resistance to boiling (related to glycol concentration and additive effects).

Principle
A 50 mL sample (coolant concentrate or diluted 50/50 with water) is heated in a round-bottom flask equipped with a condenser. The temperature is recorded when the vapor pressure equals ambient atmospheric pressure (rolling boil). The measured boiling point can be compared with reference values for ethylene or propylene glycol blends.

Purpose
To determine the freezing point of engine coolants (aqueous glycol solutions). This is critical for low-temperature performance and burst protection.

Principle
A sample is cooled at a controlled rate in a stirred bath. The temperature is continuously recorded (automatically) while the sample is seeded with ice crystals. The freezing point is taken as the highest plateau temperature observed during freezing (when latent heat of fusion is released). For automatic testers, a thermocouple/RTD and data acquisition detect the arrest of temperature drop.

Purpose
To assess the corrosion of cast aluminum alloys (e.g., engine blocks, cylinder heads) by engine coolants under heat-transfer conditions that simulate hot spots in the engine.

Principle
A cast aluminum test specimen is clamped against a heated aluminum block (simulating engine metal). The coolant flows over the hot specimen’s surface. The test runs at 135°C metal temperature and 300 kPa pressure for 168 hours. Corrosion is measured by weight loss of the specimen. This test is more severe than D1384 because it includes heat flux and localized boiling/crevice corrosion.