Why Is My Diesel Engine Making Noise While Under Load?

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Are you experiencing unexplained noise while your diesel engine is under load?

It’s one of the most common diesel engine problems, so you’re definitely not alone!

Master Diesel Mechanic Mike Schrems talked us through how to troubleshoot your diesel engine noise. Read on to see his tips on fixing the ticking or knocking coming from your engine while it’s under load.

Be sure to check out our video on it as well!

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How to Identify Your Diesel Engine Noise

So you notice a noise coming from your engine. What should you do first?

One of the most important things to note is when the noise is happening:

Does it occur all the time?
Is the ticking present only when the engine is idling?
Do you only hear it when the engine is set into motion or clutch engagement, when you let the clutch out to try and get the vehicle moving?
Or do you hear it when the engine is under load?

Knowing that the sound only happens when your engine is under load—like when you’re moving your load across the highway, come to a hill, and start to climb—gives us a clue as to what might be going wrong in your engine.

But what should you do?

How to Diagnose Engine Noise Under Load

Watch this video on YouTube

What Should You Do About Diesel Engine Noise Under Load

How to address the issue depends on exactly what’s going on in your engine. There are a few things you’ll want to keep an eye out for as you plan your next steps.

Gasket Integrity

If you find that the noise only happens when your engine is under load, then you’ll want to check the integrity of the gaskets.

If the integrity is okay, then you should check the oil. This allows you to get a handle on its condition.

Thin Oil

If the oil is too thin, it doesn’t have the lubricating ability or the extreme pressure ability to cushion that rotating port on the crankshaft. This causes the connecting rod to actually move up and down on the journal because the oil is so thin it can’t push it for that long.

But if the noise doesn’t go away, then the condition of being thin or diluted has gone into a progressive damage state. In this case, you’ll want to refer to the lower-end and do a heavier inspection.

If the gaskets have failed or they’re not good, you should replace them. This should resolve the knocking under load.

The above graphic can help you follow the troubleshooting process!

Having other problems with your diesel engine? We talk about compression issues and fuel contamination in some of our earlier posts. Check them out to learn more!