How to Diagnose Diesel Truck Engine Noises

Jul 15, 2020 | Diesel Maintenance

Has your diesel truck started making an awful knocking noise recently? Or, perhaps you just want to be aware of the issues that could occur so you can be prepared for the moment you hear a strange noise. Regardless of what brings you to this page, we will help you identify and diagnose diesel engine noises.

Many people panic the moment they hear a noise coming from their engine, but luckily, they are not all signs of engine failure or faulty parts. Any noises coming from the engine that sound like knocking, whining, rattling or anything similar, are a sure sign of an issue at hand. If you have recently purchased a diesel truck after using a gasoline one, you will notice that the engine is much louder as standard. Diesel engines are louder due to compression; the air cylinders of diesel trucks are already compressed and the fuel in injected into it, which makes them much noisier. Another reason why diesel trucks are louder, even without any issues occurring, is because the fuel used is much less filtered, so the more particles present in the fuel, the louder it becomes once it is ignited. Diesel engines are much more intricate, comprised of all kinds of valves, pipes and caps, which can sometimes sound noisy when running your truck.

Now, let’s look at the noises you may hear that are a sign of a problem that could be present in your diesel engine as well as how you can troubleshoot these issues. Do remember that with any noises that you hear, you should always take your diesel truck into your diesel specialist for further analysis. If you are in the California region, be sure to check out

Rattling Noises:

You will likely find you hear this kind of noise as you accelerate, and it is typically caused when the pre-compressed air mixed with the fuel within the cylinder are ignited earlier than they should due to compression that occurs from the engine. The technical term for this is ‘pre-ignition’ and can actually cause damage to components within your engine such as the pistons, valves and connector rods.

Troubleshooting: So, what causes pre-ignition? Usually the wrong kind of fuel! However, there could be even bigger issues which could require a belt tension to fix.

Ticking Noises:

Any ticking sound you may hear can be related to oil levels being too low, valves that have been adjusted incorrectly, or rods that are knocking.

Troubleshooting: This noise is a result of lack of lubrication, generally due to low oil, so it is important you service your truck often to avoid this. This could also be a sign of a bigger issue at hand, such as a faulty lifter or a connecting rod that has stopped working; these issues can require a complete rebuild of your diesel engine.

Knocking Noises:

This noise is a result of the injectors; they normally do make some noise, but when they are lubricated, the noise level is cut down significantly. If you do notice this sound for long periods of time while running, it may be time to take a deeper look.

Troubleshooting: You do not need to be concerned if this noise occurs for a few minutes and disappears, as this just means the injectors needed more lubrication from decent fuel. If you have used contaminated fuel in your truck, you can replace your injectors to stop this noise from happening.

Noises Related to the Timing Chain

When your engine is cold, you may hear a rattling, whereas when it is hot, it will make rattle but not so forcefully. If you notice this rattling, it could mean it is time to replace your timing chain. This component is essential as it connects the crankshaft and camshaft.

Troubleshooting: If you have caught this issue in time, you will be able to fix it by tightening it, however, if it has become too lose you will need to have it completely replaced.

To avoid the occurrence of any of these noises, it is recommended that you service your diesel truck regularly, so any issues can be flagged early enough before they cause irreparable damage.

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