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Does Coolant Level Drop When Engine Is Hot? (Explained)

Updated: Feb 2

✔ This article has been fact checked.

The coolant system in your vehicle plays a crucial role in maintaining the temperature of your engine. The coolant, also known as antifreeze, is a mixture of water and glycol that circulates through the engine block, absorbing and dissipating heat.

One of the most common questions that car owners ask is whether the coolant level drops when the engine is hot.

No, the coolant level can actually rise slightly when the engine is hot. This is due to a process known as thermal expansion. As the coolant fluid and water heats up, it expands, and some of the coolant can be pushed into the reservoir tank.

However, if the coolant level rises too much, it can lead to overflow and loss of coolant which is why it's important to not overfill your coolant reservoir.

In this article, we will explore if coolant level drops when the engine is hot, discuss how the coolant system works, and answer other related questions.

Table of Contents:

a car coolant reservoir tank