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Cracked Cylinder Liner (Symptoms & Causes)

✔ This article has been fact checked.

The cylinder liner (also known as a cylinder sleeve) is a crucial component of an internal combustion engine. It is an essential component of the engine block and serves as the bore in which the piston moves.

A cracked cylinder liner in an engine is a fracture or break in the surface of the liner that separates the cylinder from the engine block. This can be caused by excessive wear, improper manufacturing, high pressure or thermal stress, or a lack of lubrication.

In this article, we will discuss the symptoms and causes of a cracked cylinder liner, as well as the various repair options available.

Table of Contents:

a cracked cylinder liner with a red circle showing the crack up close

What Is a Cylinder Liner?

A cylinder liner is a cylindrical metal sleeve that is fitted inside the engine block. The piston moves up and down within this sleeve.

The cylinder liner is typically made of cast iron or aluminium, sometimes it's a different material than the rest of the engine. It serves as a barrier between the combustion chamber and the engine block.

different types of cylinder liners

Its Purpose

The primary purpose of the cylinder liner is to provide a smooth surface for the piston to move within. A liner also helps maintain compression and prevents leakage of coolant and oil into the combustion chamber.

It also helps in controlling the temperature of the engine, preventing overheating and damage to other components.

diagram showing the cylinder liner inside of an engine

Symptoms of a Cracked Cylinder Liner

There are several warning signs that can suggest a cracked cylinder liner in an engine. These symptoms can vary in severity and can have a significant impact on the performance and overall function of the engine.

Bear in mind that these symptoms can also be caused by other issues with the engine and may not always 100% indicate a cracked liner.

  1. Oil in the coolant

  2. Coolant in the oil

  3. Low compression

  4. White exhaust smoke

  5. Visible crack in the liner

1. Oil in the Coolant

One of the key symptoms of a cracked cylinder liner is the presence of oil in the coolant system, it can leak through any cracks and enter the water jacket (the flow of coolant) surrounding the combustion chamber.

This can lead to contamination of the coolant and could even cause damage to the engine components, such as the radiator and hoses. The coolant may also become discolored and have a milky appearance due to the oil mixing with it.

2. Coolant in the Oil

Another symptom of a cracked cylinder liner is coolant in the oil system. This occurs when coolant leaks into the oil system through the crack in the liner, resulting in the oil becoming contaminated with coolant.

This can cause damage to the engine components, such as the bearings, and can lead to a decrease in engine performance.

You can inspect the oil filler cap for a milky or frothy appearance, this indicates the presence of water and coolant in the oil.