Cummins ISX Dropped Liner Symptoms and Best Fixes

Cummins engines are renowned worldwide. The Cummins ISX engine, meant to replace the N14, was introduced in 2001. Since its introduction, it has undergone several upgrades to make it more efficient and competitive. The Cummins ISX has its fair share of problems, one of them being dropped liner.

Our article today looks at the Cummins ISX dropped line problem, which is quite common on this engine. We will explore the various symptoms this problem can exhibit and the best ways to solve the problem. At the end of the article, you will clearly understand why this problem happens and what to do whenever you detect the said symptoms.

Cummins ISX overview

Cummins ISX is a popular engine that can be found on numerous vehicles on the road, especially in North America. This engine comes armed with 2,000 lb-ft of torque and up to 600 HP. Since its launch, several changes have been made to ensure the engine fits the market and also adheres to the now strict emissions regulations, among them those of EPA.

The ISX engine is not without issues. In fact, some ISX engines made in certain years can be problematic and a pure headache to own. Among the many problems owners of the engine, encounter include faulty EGR, camshaft issues and the now nagging dropped liner problem.

The Cummins ISX cylinder liners

Like most big diesel engines, the Cummins ISX is equipped with cylinder liners. Unlike many other liners found in diesel engines, the ISX liners are mid-stock, with means they are supported by the engine block halfway. These liners are wet sleeves, meaning most of their exterior is in contact with engine coolant.

The liners in ISX boast various advantages, including cooling evenly and ensuring piston heads and rings wear out evenly. The ISX liners are fitted with a variety of seals to prevent coolant leakages. Fitting them requires high expertise and precision because a seal that doesn't fit in the right place will cause catastrophic damage later.

Another point worth noting about Cummins ISX cylinder liners is they are two different types. You can have one of 150mm and 152mm diameter cylinder liners. There is no way of knowing which cylinder is in your engine when it's still in the block. The 152 mm cylinder can't go into the 150 mm bored block, but the 150 mm liner can in a 152 mm block. The 150 mm liner in a 152 mm block will not fit correctly, and this causes it to move about, creating room for potential problems, some of which are disastrous.

Dropped Cummins ISX liners

As stated earlier, the ISX engine cylinder liners are made of cast iron. While cast iron is good for cylinder liners, they have their flaws. A dropped cylinder liner typically happens when a piston seizes or malfunctions breaking the liner at the bottom. When the liner breaks, the piston and the connecting rod will likely break free, making them move freely in the engine block. A dropped liner can destroy an engine block.

A dropped liner could also mean uneven contact with the head gasket because it's moving about or improper installation. An improperly fitted liner or a damaged one can drop out of place a few micrometers, creating space where fluids and gases can pass through.

What are the symptoms of a dropped Cummins ISX liner?

A dropped liner will exhibit certain symptoms, which might help you catch the problem early enough to help you prevent severe damage to the engine. Some symptoms are subtle and require an expert's eye, while others are quite obvious. Here are some of the common symptoms to expect;

1) Leaking coolant

Coolant leaks are the most common symptom of a dropped liner in Cummins ISX. Many who ended up with a dropped line in their hands reported excessive coolant leaking. Coolant will be squirting out of the coolant reservoir.

When the liner fails to make proper contact or when it breaks or cracks, the pressure in the combustion chamber could escape and into the coolant system. This can cause the coolant to be over-pressurized, which then causes leaks in the reservoir.

2) Coolant mixing with oil

The outside of a cylinder liner in the ISX engine is flowing with coolant to help cool down the liner and the piston head moving up and down on the inside. You may find the oil is mixed up with the coolant. Coolant could leak into the engine oil through the cracks made in the cylinder liner.

3) Low pressure

The pressure in the combustion chamber should be specific, and whenever this is compromised, there can be increased or reduced pressure. Since the coolant pressure is different from that of the oil or inside the chamber, a dropped liner will cause the pressure to drop, making the engine inefficient. Besides reducing engine performance, you may notice oil viscosity and a burning oil smell.

4) Engine overheating

Engine overheating is the most telling symptom of a dropped liner. You will find that when the liner cracks, the head gasket gets compromised, and this causes the coolant and the oil to mix. Engine overheating has also been witnessed when the liner fails to sit correctly in the engine block, leaving a gap between its edge and the gasket.

5) Metallic particles in the sump

The chipping of small metal particles from the liner will cause the dropping of the liner. As the liner parts chip off, they will likely end up in the sump. Besides other symptoms, one may find metal particles in the sump. It should then be easy to diagnose the problem if other symptoms, such as engine overheating, or coolant squirting and low oil pressure.

6) Check engine light

When the engine overheats, the check engine light will illuminate on the dashboard. The light will also light up when the compression is amiss or when the coolant leaks.

7) Engine stalling

This is not so much a symptom as an end result. When the cylinder liner breaks or cracks, the piston crown will not follow the prescribed path towards the intake valve on the cylinder head. When this happens, the piston rod which pushes the piston will twist and turn because there will be room left to do so when the liner drops. In most instances, the piston and the rod will cause extensive damage to the engine block.

8) Age

This is not a symptom, too, but there seems to be a relationship between the age of ISX and dropped liners. Many of the dropped liner complaints come from owners of older Cummins ISX engines.

How to fix Cummins ISX dropped liner problem

Many people, including experienced mechanics, misdiagnose dropped cylinder liners problem. You should run a diagnostic test to confirm where the problem is coming from. The proper diagnostic scanner and good experience solving Cummins ISX problems will help you know it is the liner and not the EGR or the head gasket causing the engine to act up.

1) Replace liners

Replacing the liners is the most practical route to take when you have dropped liner problems in the Cummins ISX. When replacing the liners, it is very important that you note the bore in your engine. You should not install a 150mm liner instead of the 152mm liner.

The other critical thing to note is that, being a wet liner, several seals must fit in place before you can say you have installed the liners. Failure to properly slide the seals in place in the ISX engine will lead to dropped liners and other problems, including a damaged engine block.

Some mechanics advise changing the liners from cast iron to steel. When handled roughly, the cast iron liners tend to chip and crack, which means you will have dropped liners. Stainless steel liners are firmer and provide adequate time for you to react and replace seized pistons.

2) Shimming

Where the liners are shorter than required, some mechanics advise adding shims to raise the height of the liners. There are special kinds of shims that can withstand the high temperature and pressure in the block.

3) Replace the engine

This is not a solution many people love to hear. In some instances, it is not even an option. However, suppose the piston and the piston rod have extensively destroyed the engine block. In that case, the most viable option is to replace the engine rather than haggling to repair it and live with an unreliable engine.

Conclusion

The Cummins ISX engine is reliable, efficient and predictable. But these traits are not so pronounced, especially when you hear of the dropped liner problems many ISX drivers and owners report. In this article, we have looked at the ISX dropped liners problem to help you know the symptoms to look out for. At the end of the article, you know what to do to solve the problems and have enough information to help you avoid making the wrong diagnosis.