5 Signs and Symptoms of a Worn-Out Diesel Engine

Diesel engines are capable of running for a long time when their owners properly care for them. In addition, many auto enthusiasts enjoy the hands-on approach of working with diesel engines. People often see the benefit that the parts of pieces of a diesel machine are so accessible. That access makes them easier to work on and understand the general mechanics of than a traditional gasoline engine.

However, diesel engines are subject to the same level of wear and tear as other vehicles. It’s often a more straightforward process to understand and even fix these five signs and symptoms of a worn-out diesel engine. Taking care of these concerns as quickly as possible allows you to keep your engine stable, reliable, and running for thousands more miles.

1. Starting Problems

An obvious sign that your engine may not be operating the way it used to is when it struggles to start up. If it continually cranks without starting, the problem is most likely low compression. If your engine isn’t compressing the fuel enough to cause combustion, you can’t gain any power, and that results in your engine not booting up.

A common first step to take would be conducting a compression test to see if that narrows down the potential cause of your engine not properly starting. As your engine ages, pistons and rings may wear down, meaning you may need to replace them.

2. Peculiar Sounds

Sometimes the easiest-to-identify sign or symptom of a worn-out diesel engine is the one you can hear rather than see. Peculiar sounds from your engine are rarely a good sign and shouldn’t go unchecked. Fortunately, some of the most common sounds are easy to identify and have straightforward solutions.


Peculiar knocking sounds are almost always a problem with your injectors. Sometimes you may just need to apply some lubrication to them to stop the sound. However, if the noise persists, replacing your injectors may be the smarter way to go.


Ticking sounds often mean that a vital part of your engine isn’t getting proper lubrication. You may want to check your valves, rods, and pistons, as these parts require lubrication to run without making the telltale ticking signs. If everything seems to be working as intended, the problem might be with a faulty connecting rod, which requires a more extensive rebuild to fix.


When you push on the accelerator and hear a strange rattling sound in your engine, it means something is wrong with your air/fuel ratio. The most frequent cause of this is a condition called pre-ignition, and it can cause damage to your pistons and connecting rods. Fortunately, the most common fix is just using a different type of fuel or checking the tension on your engine belts.

3. Unusual Exhaust

Smoke is typically a bad sign when it’s coming out of your engine. On the bright side, it may surprise you to learn that the type of smoke you see can help you narrow down what the problem might be. Identifying the type of smoke your engine creates gives you a better idea of how you can fix it.

White Smoke

If you notice white smoke coming from your exhaust, it typically suggests that raw fuel isn’t burning while passing through your exhaust system. The most frequent causes of white smoke are low cylinder compression or defective fuel injectors. If your valves leak or your piston rings stick, you may experience some white smoke.

Blue Smoke

If you see blue smoke, it’s because oil from your engine is leaking into your engine’s combustion chamber. The problem could be as simple as someone using an incompatible grade of oil. Alternatively, it could be something more serious, such as a worn down cylinder or a thin oil due to fuel dilution.

There are times when you may briefly see blue smoke from the exhaust after a cold start, but it can fade away without creating much trouble. If you regularly see blue smoke, though, you may want to check for oil leaks or try a different form of lubricating oil on your engine.

Black Smoke

Thick black smoke is the most common color exhaust your engine may emit because so many different issues can lead to it. Black smoke typically comes from incomplete combustion of your fuel and may stem from dirty injectors, an imbalanced air/fuel ratio, or merely just from poor fuel quality. However, it may also come from overloading your engine or a faulty EGR system. It is in your best interest to watch for how regularly your experience the black smoke.

4. Increased Fluid Consumption

One of the main reasons why people love diesel engines is because of their excellent fuel economy and ability to handle oil and other necessary fluids. However, there may be some instances where you need to top off the oil more than you expected. You can examine your engine for any wet spots that may showcase visible leaks. However, your engine may sometimes drain the oil without leaks by slowly burning it and sending it out through the exhaust. Pay close attention to how often you need oil changes to see if there are any irregularities.

If your engine is burning fuel faster than it should, your injectors may be leaking excess fuel and need replacing. Fortunately, you might also be able to catch this by observing black smoke. Diesel is already expensive, so you don’t want to spend more at the pump than you need to.

5. Rough Idle

If you notice some sudden shaking or rumbling when you stop at the traffic light, you may have trouble with your fuel pump. The pump may leak fuel, or the timing may be off, making it unable to produce a consistent air/fuel mixture in your car. It’s worth examining the cause of the rough idle so that you can prevent any further damage and ensure you have a smoother, more comfortable ride.

When you need to repair or replace parts in your diesel engine, let ATL Diesel handle your needs. Our parts are compliant with OE standards and guaranteed to fit your engine like new. Our online system allows us to use your engine number to help you find the exact parts you need. If you need a C15 Acert single turbo conversion kit, ATL Diesel is here for you with the products and knowledge you need. To speak with a member of our team, contact us anytime—we’ll be happy to assist you.

5 Signs and Symptoms of a Worn-Out Diesel Engine

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