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February 20, 2024

5 Signs That You Need To Overhaul Your Truck Engine

Truck Engine Overhaul

More than 288,000 heavy trucks were produced in the United States in 2021. That’s an increase of about 20% compared to 2020 but not yet a match for the pre-pandemic record years of 2018 and 2019. As a result, many of America’s 1.9 million truckers are on the road driving older trucks. 

Using an older truck is not necessarily a disadvantage, but it does mean that you need to look out for signs indicating a need for maintenance. Engine problems are among the biggest potential issues heavy-duty truckers could be facing. To spot potential issues early, look out for these five signs that may indicate your engine needs an overhaul. 

What is an Engine Overhaul? 

Before looking at indicators of engine trouble, let's clarify what an engine overhaul involves. One simple way of thinking of engine overhauls is to imagine giving a truck engine a new lease of life. 

There is no need to wait until issues arise. Most manufacturers recommend overhauls after a certain number of years or miles, whichever happens first. It is relatively common to consider overhauling an engine after seven to ten years of running it or once the truck has completed 800,000 to one million miles. 

During the overhaul itself, expert mechanics will take your truck engine apart and repair or replace any parts that are failing. Ne gaskets, rings, and oil seals are common replacements during an overhaul. The goal is simple – allow your truck to function normally again. 

How to Know That Your Truck Engine Needs an Overhaul

If you’re spending weeks on end on the road, it’s only normal that you get to know your truck. You know what it feels like when it runs well. The more time you spend with your vehicle, the easier it becomes to realize when something is not right, even if you’re not mechanically trained. Here are five of the most common signs to show you that your truck’s engine may need an overhaul. 

  1. Lower fuel economy
  2. Higher oil consumption and low oil pressure
  3. Excess black or white smoke
  4. Knocking or other sounds
  5. Lack of acceleration

1. Lower Fuel Economy

Fuel prices have been increasing over the past year or so, making fuel economy more important than ever before when it comes to running a fleet economically. Some class 8 trucks are known for their outstanding fuel economy, averaging more than ten miles to the gallon. Of course, fuel economy also depends on the routes you travel. For example, traveling uphill frequently can increase your consumption because the engine needs to work harder. 

If you’re starting to notice that you need to pull in to refuel more often, ask yourself whether your route has recently become more challenging. If that’s not the case, it may be time to consult a mechanic. Lower fuel economy not only raises ongoing costs but may also indicate a more serious underlying issue. 

2. Higher Oil Consumption and Low Oil Pressure

Just as changes in fuel consumption can indicate the need for an engine overhaul, differences in oil use and oil pressure can do the same. Both issues are related to the natural wear and tear of engine parts. 

As engines get older and parts are becoming stressed by long-term use, the space between those parts increases. When it is burned off, excess oil could escape into those spaces. In addition, higher oil consumption may indicate a leak somewhere in the system, again predisposing truckers to other failures. 

Low oil pressure could mean that oil is not reaching all the components it should lubricate. That puts those parts at risk for failure and requires a mechanic’s attention sooner rather than later to prevent further damage. 

3. Excess Black and White Smoke

Modern trucks shouldn’t be emitting large amounts of smoke of any color. Modern engines are simply built in a more sophisticated manner.

If you’re noticing black or even bluish smoke coming from your exhaust, one or several of your truck’s cylinders could be burning oil. Check your oil consumption to confirm your observation and ask a mechanic for help. They will likely replace bearings, valve guides, or piston rings. 

Aside from oil, dark smoke may also be a sign of your fuel system running too rich or too lean. Again, a trained mechanic will be able to identify and solve the issue. 


White smoke, on the other hand, could indicate that coolant has escaped into one more of the engine’s cylinders. 

4. Knocking or Other Sounds

Anyone who has driven a vehicle for some time will be familiar with its sounds. You may even stop noticing those sounds after a few days or weeks. 

However, when you hear strange sounds coming from a truck engine, it’s time to pay attention. Knocking sounds are among the most serious indicators of engine problems. They may be caused by too much space between the piston and the cylinder bore and need to be addressed immediately. Broken piston rings tend to cause rattling sounds, whilst valve train issues generally result in chattering sounds. 

If you think your truck is starting to sound different, consult a professional straight away. 

5. Lack of Acceleration

Granted, trucks are not racing cars, but most heavy truck engines are powerful enough to respond quickly when your foot hits the accelerator. 

Again, with time, you get used to how your vehicle picks up speed. If you’re suddenly struggling to accelerate, your truck may be losing compression. Potential reasons for loss of compression include worn-out piston rings, a blown head gasket, or a crack in the cylinder head. 

Your mechanic will run a series of tests to identify the issue and advice on the best course of action. 

Final Thoughts

Modern trucks are built to last millions of miles and years on end. However, that doesn’t mean they will never require maintenance, including an engine overhaul. Understanding the signs that may indicate the need for an overhaul will help you minimize the costs associated with the job and keep your truck running smoothly.