How To Fix the Knocking Sound in Any Diesel Engine

It’s normal for engines of all sorts to make noises. The slow rumbles, rattles, hums, and occasional knocking could mean your engine is perfectly fine. In fact, it’s always a smart idea to have a general recollection or understanding of what your engine typically sounds like. When you know how it sounds when everything is normal, you can have a better ear for when things start going wrong.

There are many possible noises that your engine can make, and here are some tips on how to fix the knocking sound in any diesel engine. Join us at ATL as we explain how to identify strange noises, the probable causes, and what you can do to take care of them.

Diesel Engines vs. Gasoline Engines

Both types of engines are prone to making noise. However, you can ask any auto enthusiast, and they'll tell you how different the familiar sounds are between these two types of engine models. While both diesel and gasoline engines rely on combustion for power, the distinct method in which they achieve this can lead to some noticeably different noises. Diesel engines inject fuel into the cylinder and ignite the compressed air as opposed to gasoline engines which ignite through spark plugs and other similar mechanics.

Diesel engines are generally a lot noisier because of this process and because they have more moving parts like valves, pipes, and metal caps that can shake and rattle a bit. The important thing to understand about this is that these sounds are not inherently bad and are an essential part of your engine functioning. A common problem people run into with diesel engines is failing to notice a shift in these sounds that can wind up doing much more damage when left unchecked.

The Most Common Types of Knocking Sounds

Understanding why and when different problematic sounds occur within your diesel engine makes it much easier to identify the causes. Try to note when these sounds amplify and how they impact your engine while you're driving or idling.

Peculiar Rattling Sound

A rattling sound is a quick, typically unsteady series of noises. Many drivers may notice this sound amplifying and increasing when they accelerate. This fast, disjointed sound is generally easy to identify and one you want to pay attention to.

Consistent Ticking Noise

Ticking sounds are generally more consistent both in tone and tempo. These high-pitched clicks may be noticeable during an engine idle or while driving without pressing on the accelerator.

Loud Repetitive Knocking Sound

Knocking sounds may come out as a combination of the previously mentioned noises. Knocking sounds are typically lower in pitch, which makes them louder and easier to recognize. You may hear these thuds and knocks during an idle position or while speeding up. The tempo may also vary depending on your speed, making them either more consistent or slightly erratic. Either way, a knocking sound is generally cause for concern, and you want to take care of it as quickly as possible.

Most Likely Causes of These Sounds

Now that you know what sounds to listen for, you may want to know what’s causing them. While there may be more serious, underlying causes, here are some common culprits behind these sounds. These sources can help you narrow down the source and check for yourself if anything seems amiss.

Source of the Rattling

The most common cause of a loud rattling sound upon acceleration is a condition called pre-ignition. Essentially, your diesel engine is igniting your air/fuel mixture prematurely, throwing off the designated timing of your overall system. Pre-ignition may lead to serious damage to your pistons, connecting rods, and valves, so it’s not a problem you want to ignore.

Cause of the Ticking

Ticking sounds are often harder to narrow down because there are several potential causes that create similar sounds. Most frequently, you have a reciprocating part of your engine like the pistons, rods, or valves. This reciprocation means the pieces are moving back and forth in a straight line rather than in the natural rhythm so that the ticking may result from minor clings or clangs against part of your engine. Some of the most common causes of this phenomenon are low oil levels, noisy lifters, or improperly adjusted valves.

Root of the Knocking

Knowing how to fix the knocking sound in any diesel engine is easier when you can identify the source of it. Almost every knocking sound worth worrying about comes from poorly lubricated fuel injectors. Basically, your engine is mistiming fuel release from the injector with the piston’s movement, which can result in a loud, unpleasant sound.

How To Fix These Sounds

After narrowing down the general causes of these sounds from your diesel engine, you can do your best to fix them. Some of these fixes may involve cleaning or replacing some basic parts. However, if the problems persist, you may want to take your vehicle to a dedicated specialist and get their input on the situation.

Solving the Rattling

A common cause of pre-ignition is using the wrong fuel type in your engine. Flushing your fuel system and replacing it with one more compatible with your engine may remove the rattling and solve your ignition problem.

Removing the Ticking

In the best-case scenario, the ticking sound from your car may be from low oil levels, so getting an oil change may fix it. However, in a much rougher scenario, you may have a bad lifter or faulty connecting rod. These are much more serious problems and may require rebuilding the engine.

Taking Down the Knocking

Improperly timed fuel injectors are the most likely cause of your engine's knocking sound, so getting a fuel additive to help lube them up may solve the problem. If the knocking sound persists after attempting lubrication, the smartest option may be to replace your injectors with new ones either in your home garage or with a certified mechanic.

ATL has everything you need if you’re looking for high-quality, reliable replacement parts for your diesel engine. We have rebuild kits for major diesel manufacturers that are closer in quality to OEM-certified parts than other aftermarket sources. Whether you need a CAT platinum overhaul kit or specific parts for a Detroit series 60 engine, let ATL help you find the necessary parts. You can use our online store to punch in your serial number, and we'll help you find the right parts without all the hassle. If you have any additional questions, comments, or concerns, please don't hesitate to contact us anytime, and a member of our team will be happy to get you back on the road.

How To Fix the Knocking Sound in Any Diesel Engine
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