10 Urgent Signs You Need A Diesel Engine Repair

10 Signs Your Fleet Vehicle Needs a Diesel Engine Repair

Diesel-powered vehicles are built to last, but they still need service. Diesel engine maintenance and repair are required to get the most out of any motor.



Diesel-powered vehicles are built to last, but they still need service.

Unlike traditional gasoline-based powertrains, the diesel engine in a bus or other transit vehicle can routinely rack up more than a million miles before it needs to be replaced or rebuilt. Nevertheless, diesel engine repair and maintenance is required to get the most out of any motor.

In this Article

Diesel Engine Repair: What You Need to Know

If you’re wondering whether it’s time to perform some engine service to your fleet vehicle, keep reading for the 10 most common signs of engine trouble.

Reduced Power

One of the most obvious issues that can result when a diesel engine needs repairs is that the vehicle experiences a noticeable lack of power. This can exhibit itself in sluggish acceleration or even difficulty starting the motor. 

If something just doesn’t seem right about how the vehicle is running and driving, the problem might lie in the fuel injectors or some other critical engine component.

Diesel Engine Repair: What You Need to Know

Excessive Black Exhaust

Diesel engine operators are used to seeing exhaust billow out of their vehicles’ pipes from time to time. When it becomes too much to ignore, however, there could be an issue with the engine. The culprit might be the air filter, turbocharger, injector pump, or a number of other related parts. Driving around with too much exhaust could cause odor problems, breathing issues, and might even run afoul of local laws and regulations.
Quality Assurance | Quality Management Control Plan | Fleet Maintenance | Diesel Engine Repair

Unusual Loud Noises

Another sign that an engine might need attention is the prevalence of especially loud sounds coming from under the hood. Of course, diesel engines are typically louder than their gasoline or electric counterparts, but any driver will notice when it becomes noisier than usual. 

Depending on whether the sound is a ping, a knock, or some other variation, there are several places a mechanic might want to look for problems. In any case, such an unusual sound is likely a surefire sign that it’s time to take the vehicle in for diesel engine repair.

Increased Appetite for Oil

No driver enjoys frequently topping off a diesel engine with oil. When it becomes a persistent problem, however, it’s probably due to something more serious than just a minor leak. Be sure to have the engine serviced as soon as possible. 

Even if there’s no evidence that oil is leaking on the parking lot where the vehicle is kept when not in use, there could still be serious problems. The bottom line is that if you’re adding oil regularly despite getting your fluids changed on a consistent schedule, there’s probably a serious issue that needs to be addressed.

Reduced Fuel Economy

With the price of diesel constantly fluctuating, it’s easy to become complacent when reviewing your fuel bills each month. That’s why it’s important to keep a close eye on how many miles per gallon each fleet vehicle is getting. 

If there’s any significant reduction in that number without a rational explanation, consider that evidence to be a red flag. Take your vehicle in for an engine diagnosis and repair as soon as possible.

Trouble Cranking

Few things are more annoying than getting into a vehicle and turning the key only to hear the cranking of the engine without any ignition. While there are several possible reasons for this serious problem, one of the most common lies in the engine’s compression. 

In a diesel engine, if the compression is too low then there won’t be the combustion necessary to get the motor running. It could be a relatively minor fix such as worn-out seals. In any case, getting the engine serviced quickly will help ensure you don’t lose any valuable time on the road.

Excess Moisture

When a diesel-powered vehicle is left in especially humid or wet environments for an extended period of time, the engine can become damaged. Look for evidence of moisture or humidity to determine whether your vehicle needs diesel engine repair as a result. 

Left unchecked, this added moisture can result in engine knocking and other potentially expensive problems.

Bluish Smoke

In addition to looking out for an elevated amount of black exhaust, it’s also vital to notice any blue-tinted smoke that comes from your diesel vehicle. This is a telltale sign that the engine has been burning oil, which is never a good thing. 

It’s increasingly common for aging engines to develop this problem, so if your fleet is getting on in years, be sure all drivers are aware of the warning signs of a costly diesel engine repair so any issue can be addressed sooner rather than later.

Glow Plug Failures

All experienced diesel drivers understand the important role that glow plugs play in creating the combustion necessary for the engine to start. When they start to go bad, the result can be difficulty cranking and igniting upon turning the key. 

Identifying this issue as soon as it becomes apparent will help avoid even more extensive damage to the engine and other powertrain components.

Incorrect Viscosity

Trained bus technicians who have worked on transit diesel engines know there’s a significant difference in the weight viscosity of each type of oil. It’s notably higher in diesel engines and the right level can change depending on the season. 

This might confuse some individuals who are used to working only on gasoline-powered vehicles, so keep an eye out for signs that the wrong weight might have been added to the engine, which can cause additional noises and costly damage.

Final Thoughts

Transit buses are essential for our City’s mobility. As a fleet operator, knowing the warning signs is a great first step toward preventing engine failure leading to an  extensive overhaul for your fleet vehicles. 

Checking the list above and remaining vigilant about documenting any unusual behavior can go a long way towards preserving any diesel engine repair for as long as possible. 

If you’re still not sure whether your vehicle needs diesel engine repair, NEBR is a leader of diesel bus maintenance that continuously performs Mid-Life Bus Overhaul Program and we can help. Call us today and speak with a trained professional who can get you started on the diagnostics process. 

Be sure to share this article with other transit bus industry managers to help them stay on top of the maintenance and repairs they might need in the future.

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