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Troubleshooting Your Cummins Diesel Truck Engine

By: Cleveland Brothers
May 14, 2021

Cummins is one of the largest manufactures of diesel engines in the world. Their heavy-duty products power a wide range of equipment spanning multiple industries, including mining, construction, trucking and logistics, agriculture, drilling and more. If you’re using a Cummins engine, we’ll help you troubleshoot the most common issues so you can stay productive and keep expenses low.

Are Cummins Engines Reliable?

As long as you’re following an appropriate plan for your scheduled maintenance, you can expect Cummins engines to deliver consistent and dependable performance. Like all equipment, occasional issues come up that require a fix. The good news is, if you’re experiencing engine trouble, it might be something you can fix yourself—even when on the road.

Common Cummins Engine Problems and Troubleshooting Steps

The first step in troubleshooting your Cummins diesel truck engine is recognizing you have an issue to correct. Most engine problems will display symptoms. These signs will provide you with a starting point for your troubleshooting process.

Act fast once you realize there’s an issue. The longer things go unresolved, the more trouble you risk creating further down the line. Things that start small will often snowball into more significant problems, causing more downtime and costing more to fix.

1. The Engine is Overheating

Engine overheat is one of the most common issues with semi-truck engines. High temperatures can result from too much demand or an internal fault. In the best-case scenario, an overheat causes unplanned downtime while you wait for things to cool down. If the engine runs hot for too long, it can damage your pistons, crankshaft and cylinders and lead to other costly consequences.

If your diesel engine is overheating, shut it off as soon as possible. When it’s safe:

  • Check your airflow: Make sure your cooling fan is working and check for proper airflow to the radiator.
  • Check your undercarriage: Check your axles and tires to ensure they’re rolling freely without causing friction.
  • Check your thermostat: Ensure your thermostat is functioning properly and initiating engine cooling processes.
  • Check your fluid levels: Low oil and coolant levels can cause overheating. Check levels when the engine is cool.
  • Check the outside temperature: Cummins engines are reliable, but excessive ambient temperatures can cause issues.

2. The Engine Won’t Start

When engines struggle or fail to start, it could be due to several causes. Some of the more common include problems with the fuel supply, air intake issues and battery troubles. In many cases, these problems will display minor symptoms before turning into risks that threaten productivity.

If you experience difficulties starting your engine, or you’re getting no response, start your troubleshooting process by:

  • Testing the battery: Check the connections between your battery and starter. If those are good, test the battery.
  • Tracing the fuel supply: Trace your fuel lines and replace your fuel filter. You may also want to test for contamination.
  • Inspecting your air filters: Remove your air filter and shine a flashlight through it. If you have trouble seeing the light, replace it.

3. The Engine Produces Smoke

Cummins engines comply with modern emissions regulations and provide operators with safe working environments. If your heavy equipment or semi-truck engine is producing an excessive amount of smoke, that’s a warning sign something is going on that requires your attention.

The color smoke you see will give you insight into the cause behind the issue:

  • White smoke: White smoke typically means your fuel isn’t getting hot enough to burn and is traveling through the exhaust system instead. This issue might be due to incorrect timing, a clogged fuel filter or low compression.
  • Blue smoke: Blue smoke indicates you’re burning oil. While often mildly present at startup in colder temperatures, excessive or persistent blue smoke means you likely have a damaged component or connection or are using the wrong oil.
  • Black smoke: Black smoke is the most common. This smoke is produced during combustion and is dark because it’s filled with carbon exhaust particles. It usually means you have an improper fuel-to-air ratio caused by damage or a clog in the air or fuel system.

Engine smoke is often accompanied by a rough idle. In most cases, addressing the cause behind your smoke will eliminate the problem.

Tips on Caring for Your Cummins Engine

Proactive care is the best way to keep your engine in peak condition and extend its useful life. A little work on the front end can help you avoid many common Cummins engine problems and experience the most uptime.

To take care of your diesel truck engine, make sure you:

  • Change your filters regularly: Clogged air, fuel and oil filters are the root cause behind numerous symptoms and Cummins engine problems. Replacing all of them on a set schedule will help ensure your engine always gets the uninhibited airflow and fluids it needs to perform its best.
  • Monitor your fluids: Checking your engine fluids regularly will help you avoid repairs and many other issues. This step can also help you identify other issues like leaks or faulty components by alerting you to faster-than-normal fluid consumption. If any are running low, top them off and make a note to monitor them.
  • Keep the engine clean: Diesel engines produce soot and collect grime that can impact how well the engine operates and shorten its life span. Regular cleaning will keep your engine free from any buildup, helping you get the best performance. It will also make it easier to spot any developing issues, like leaks or broken hoses.

Trust Your Cummins Engine Care to the Experts

The simplest and fastest way to troubleshoot your Cummins diesel truck engine is to leave things up to the team at your nearest Cleveland Brothers RIG360 Truck Center location. We have multiple fully equipped service centers throughout Pennsylvania and northern West Virginia. Our technicians have the training and experience to take complete care of your engine, including maintenance services, fluid testing and comprehensive repairs. We also offer field service if you have an emergency and need to get back up and running.

Find your nearest branch location to schedule a service appointment for your semi-truck engine. If you have questions, please contact a sales rep today.

This content is created and reviewed by the Cleveland Brothers RIG360 Truck Centers team. Offering bumper-to-bumper service on all makes and models of trucks, Cleveland Brothers RIG360 Truck Centers is dedicated to providing quality service and repairs to your entire truck.
Contact our team today for more information.