What Causes Coolant to Boil Over?

[BlakelyRose]

The main reason for coolant boiling over is damage to the bottom of the coolant reservoir. Below are the relevant details:1. Introduction: Coolant is used in the cooling systems of automobiles, diesel locomotives, tractors, ships, engines, radiators, and various mechanical equipment such as diesel and gasoline engines. It serves multiple functions including antifreeze, anti-boil, anti-corrosion, and anti-scale protection. Water has a boiling point of 100°C, while high-quality antifreeze coolant typically boils at around 110°C, making it less prone to boiling over than water during summer use.2. Causes: Damage to the coolant reservoir cap, excessively high temperature inside the reservoir. Coolant level exceeding the upper mark on the reservoir. Thermostat malfunction leading to overheating, preventing coolant from circulating through the engine's water passages for major cooling cycle.