Cracked Cylinder Liner (Causes & Signs)

Last Updated on: 7th September 2023, 12:46 am

The cylinder liner, which is also referred to as a cylinder sleeve, is a vital part of an internal combustion engine.

It is an integral component of the engine block and functions as the cylindrical bore in which the piston moves.

A cracked cylinder liner in an engine is a fracture on the liner’s surface that separates the cylinder from the engine block. This can be caused by excessive wear, improper manufacturing, high pressure or thermal stress, or insufficient lubrication, among others.

In this article, we will cover the symptoms and causes of a cracked cylinder liner and explore the different repair options that are available.

What Is a Cylinder Liner?

A cylinder liner is a metal sleeve that’s fitted inside the engine block. It’s cylindrical in shape and provides a surface for the piston to move within.

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

Purpose of a Cylinder Liner

The cylinder liner plays an important role in maintaining compression and preventing leakage of coolant and oil into the combustion chamber.

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

Cracked Cylinder Liner Symptoms

If the cylinder liner cracks, there are several symptoms that may occur.

These can include a decrease in engine power, excessive smoking, coolant or oil consumption, engine overheating, and loss of compression.

However, it’s worth noting that these symptoms can also be caused by other engine issues and may not always 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 Cooling System

When a cylinder liner is cracked, it can cause various symptoms that could have a significant impact on the engine’s performance.

One of the main indications is the presence of oil in the coolant system.

If there are any cracks in the liner, oil can leak and enter the water jacket that surrounds the combustion chamber, which can contaminate the coolant.

This contamination could damage engine components like the hoses and radiator, and the coolant could become discolored with a milky appearance due to the mixing of oil and coolant.

2. Coolant in the Oil Passages

Another symptom of a cracked cylinder liner is the presence of coolant in the oil system.

Coolant can leak through the crack and contaminate the oil system, causing damage to engine components like bearings and reducing engine performance.

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

3. Loss of Compression

A loss of compression in the engine is also a common indication of a cracked cylinder liner.

The crack allows the air and fuel mixture to escape from the combustion chamber, reducing compression pressure, and can lead to poor engine performance, misfiring, or stalling.

Additionally, escaping combustion mixture can increase pressure within the coolant or oil system and cause further damage.

You can check for exhaust gasses in the coolant system with a combustion leak tester, this will help indicate whether or not you have a cracked liner.

4. White Smoke From the Exhaust

If the cylinder liner is cracked, you may notice white smoke coming from the exhaust, which happens when coolant enters the combustion chamber through the crack in the liner.

This symptom is a clear indication of a crack in the liner and should be addressed immediately to avoid further damage to the engine.

5. Visible Crack

In some cases, a crack in the cylinder liner can be visible, and a diagnosis can be made by a visual inspection.

You can use a borescope to search for cracks in the cylinder sleeves, this is a good start but in most cases, a more detailed inspection is required to determine if there is a crack.

Typically, this inspection involves removing the cylinder head and visually examining the liner for cracks and fissures.

A visible crack in the liner is a clear indication that the liner is damaged and should be addressed to prevent further damage to the engine.

Why a Cylinder Liner Could Crack

Cylinder liners are crucial parts of an engine and endure harsh conditions such as high temperatures, pressure, and stress.

Over time, these conditions can weaken the cylinder liners, causing cracks that could seriously affect the engine’s performance and lifespan.

Various factors can cause cylinder liner cracking, including the following:

1. Weak cylinder liners
2. Excessive power
3. Overheating
4. Heat spots and swelling
5. Incorrect installation
6. Knocking
7. Combustion chamber contamination

1. Weak Cylinder Liners

Using weak or low-quality materials in manufacturing the cylinder liners is one reason for cracking. The liners may not withstand the engine’s intense conditions and thus become more prone to damage.

2. Excessive Power

If the engine produces more power than it was designed to handle, it can result in excessive stress on the cylinder liner, leading to cracking. This can happen, for example, when remapped or tuned.

3. Overheating

When the engine overheats, the cylinder liner can experience excessive expansion and contraction, leading to cracking.

Issues with the cooling system such as a clogged radiator, a faulty thermostat, or low coolant levels can cause overheating.

4. Heat Swelling and Heat Spots

If the cylinder liner heats up more in one area than another, it can cause uneven expansion and contraction, leading to cracking.

Heat swelling and heat spots can occur due to a malfunctioning cooling system, such as a faulty water pump, a low coolant level, air in the system, or a clogged radiator.

5. Incorrect Installation of Pistons or Liners

Improper installation techniques or the use of incorrect parts during the installation of pistons or cylinder sleeves can cause excessive stress on the liner and lead to cracking.

6. Engine Knocking

Engine knocking can cause excessive vibration and stress on the cylinder liner, leading to cracking. Knocking can be caused by issues with the engine’s fuel delivery system or the use of low-quality fuel.

7. Contaminants in the Combustion Chamber

Contaminants in the combustion chamber, like dirt, dust, and debris, can cause corrosion and damage to the cylinder liner over time, potentially leading to cracking and other forms of damage.