Signs That Your Heavy-Duty Truck Needs An Engine Repair

July 11, 2023

Guide: Spotting heavy-duty truck engine issues. Proactive maintenance for optimal performance. Save time, money, prevent damage. Let's dive in!

Signs That Your Heavy-Duty Truck Needs Engine Repair

Welcome to our comprehensive guide dedicated to helping you recognize the signs that your heavy-duty truck may require engine repair. As the owner or operator of a powerful vehicle, it is crucial to be aware of the warning signals that indicate potential engine problems. 

In this guide, we will highlight key indicators to watch out for, allowing you to take proactive measures to maintain your truck's engine's optimal performance and longevity. By recognizing these signs early on, you can save time and money and prevent further damage. Now that’s out of the way, let's dive in.  

Engine Repair Warning Signs

Oil Sludge 

Oil sludge is wasted oil and grime that gets mixed with your clean oil, causing it to become thick and contaminated, and is a sign of a worn-out engine without sufficient lubrication. Coolant can also contribute to this mix, suggesting that your coolant system has a leak, which causes its own range of problems. 

The most common causes of oil sludge include using low-quality oil, skipping oil changes, using contaminated coolant or moisture, and frequently idling for extended periods. 

Metal Shavings in the Oil  

Metal shavings found in the lubrication are another indicator of an engine needing repair. In fact, this is a great test to diagnose superficial damage to the engine's components. This is because it will collect shaving from the damaged components as the oil passes through them. It will then be up to a professional to locate the damaged components.

Increased Oil Consumption

Depending on who you ask, oil should be changed every 3,000 miles because, unlike other fluids in your truck, it is difficult to determine discoloration. Although healthy, uncontaminated oil should be changed every 5,000 - 7,000 miles. If your truck uses fully synthetic oil, then this can last up to 15,000 miles. 

If you find yourself having to change your oil more frequently than the above, then it could be a sign of worn-out piston rings that are causing an oil leak within your engine. This can lead to decreased lubrication and increased friction, which will cause component damage. 

Excessive Exhaust Smoke

Because your vehicle produces a large amount of smoke as it is, it may be hard to properly determine what is excessive. However, the color of the smoke can help diagnose some internal issues. 

  • Blue: Your engine is burning oil 
  • White: Your engine is burning coolant with fuel 
  • Thick white smoke: Leaking head gasket 
  • Black: Your engine has a blocked manifold, clogged engine air filter, or malfunctioning fuel injection system 

Another way to determine this is by noticing any strong odors, such as a burning smell, which is a clear sign of internal engine wear. If you notice that it has a sweet smell, this is due to an engine coolant leak. 

Reduced Fuel Efficiency

If you’re driving in a city, then you should be able to get six to nine miles per gallon, whereas you should be getting 11 on the highway. If you find yourself visiting the gas station more regularly than usual or you’re losing power, then this is not a good sign. 

A number of problems, such as damaged sensors in your engine control module (ECM), clogged fuel injectors, or ignition system issues, may be to blame for this. 


Engine overheating is a serious concern that requires immediate attention. Your temperature gauge reaching high levels and steam under the hood are warning signs to be aware of.

Typically, issues with the cooling system—such as leaks, faulty thermostats, poor water pumps, or clogged radiators—cause this. Remember that this is a serious issue and can cause your engine to catch fire, which can pose a serious threat to safety on the road.

Decreased Performance 

This can be in the form of reduced acceleration, difficulty climbing hills, stalls, excessive vibrations, rough idles, or decreased towing capacity. This could result from leaking engine cylinders or issues with fuel injectors or glow plugs, which cause a loss of compression, leading to a failure to ignite. 

Unusual Noises 

Be on the lookout for knocking, rattling, grinding, or hissing sounds. 

These can result from compression issues, faulty fuel injectors, a failing wrist pin, damaged pistons, loose belts, or bad bearings. 

Warning Lights 

Learn to recognize the warning lights on your dashboard, including: 

  • Engine warning light 
  • Engine oil pressure light 
  • Engine oil level 

This means that your onboard computer (ECM) has detected an issue that can range from minor concerns to major problems. 

Consequences of Heavy-Duty Engine Failure 

Failing to address any of the above issues can lead to a range of problems for you and you’re heavy-duty truck, including: 

Increased Damage 

Issues will worsen over time if left unchecked. For example, a small oil leak can soon develop into major engine damage, especially if the oil level drops too low or contaminants enter the engine. 
This can increase the cost and time needed to carry out repairs, as well as cause potentially irreversible reputational damage through missed deadlines. 


Engine failure can cause your truck to stop suddenly. This is not only inconvenient but can cause delays, miss deadlines, and incur towing costs and fees for emergency recovery, on top of safety concerns

Reduced Performance and Efficiency

A gradual decline in fuel efficiency, output, acceleration, towing capabilities, and overall drivability reduces overall truck performance as well as incurring higher operational costs. 

Safety Risks 

Sudden engine failure can lead to a loss of control, posing the risk of accidents on the road. Some types of engine failure can even cause your engine to catch fire, causing further damage down the road.

Final Thoughts 

Your heavy-duty engine is a complex piece of machinery with a number of different components that can fail. Being aware of these signs can help you nip these issues in the bud quickly so that you can get back on the road in no time. 

However, neglecting these is extremely unadvisable. Aside from the worsening of the damage in your engine, this can cause your vehicle to be out of commission for longer than needed, costing more money and causing potentially irreparable damage to your business’ reputation. In some cases, it can pose a risk to yourself and other road users. Be aware of the signs of engine failure and get in touch with professionals like our truck engine mechanics at Neudorf Enterprises immediately for resolution.