How To Diagnose A Diesel Engine Problem

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Regardless of the vehicle type you have, breakdowns are commonplace nowadays. Their frequency tends to increase the older it gets. Yet if you want your car to last long, you must prioritize regular maintenance and service because car engines have many moving parts that will wear away over time. So, they need replacement or repair regularly.

However, some engine problems could develop despite a perfect service record. Emergencies may require you to do some quick fixes to your car so that you can get moving. Therefore, it would help if you knew how to diagnose your diesel engine.

An engine problem is sometimes complicated, so you may need to go to an experienced mechanic or call a truck repair for roadside help. For the times that they aren’t, you need to have your own diagnostic tools on hand to identify engine problems on your own. That said, here are some common diesel engine problems and their possible diagnosis:

  1. Starting Problems

If your car refuses to start, there could be a lot of reasons why this could be the case. The most obvious thing you need to check is whether the battery terminals are correctly connected. Confirm if the dials are lighting up. If the car still won’t start, the battery may be flat, or the starter has a problem.

You should check the fuel supply, too. Combustion will not occur without a proper fuel supply, and the car will certainly not start. Perhaps a clogged fuel filter or faulty fuel pump or injectors is why not enough fuel is pumped to the combustion engine chamber. Moreover, the fuel supply mechanism could malfunction because of contaminated fuel. Therefore, you’d need to have these parts cleaned or replaced. If you’re unsure about your ability to address such cases, perhaps your mechanic should fix the problem because replacing things like injectors isn’t exactly a simple process.

You may also want to check the condition of the air filter because a clogged filter could also cause insufficient air supply to reach the engine. Hence, replace the air filter if you need to.

  1. Engine Overheating

This is perhaps one of the most common problems in diesel engines. When the engine overheats, it’s a sign that you are pushing it too hard. Your car’s engine may get to this point because a part isn’t working correctly or has seen better days. When an engine overheats, address the issue immediately because it can have significant side effects.

Check whether your engine’s fan and belts are working correctly. You also need to check whether the airflow to the radiator is working as it should. This is because bugs could collect in the radiator, affecting the airflow. Hence, fans won’t work well if a belt is worn out or out of position. So, it’s either you fix the belt or replace it.

Besides, while your engine is cooled down, see whether the oil and coolant levels are okay. Check if any leaks are causing a problem. If the coolant runs out, the engine will overheat. If the oil level is low, the engine may overheat, too. Oil leakages usually result from worn-out parts like gaskets and seals. If you don’t fix these parts in good time, it could lead to engine failure eventually. If that doesn’t work, you also need to check whether any bearing isn’t functioning well.

  1. Stalled Engine

There’s nothing more frustrating than having your car engine stall on you in the middle of the night. There are many possible causes for this. The first thought that may come to mind is that the fuel has run out. However, if your fuel gauge says there’s still some left, check whether the fuel injectors may have become faulty. Remember, if fuel doesn’t get adequately pumped through the system, the car will not run, which would explain the sudden stalling of the engine. If the injectors are problematic, the car may not start again until these injectors are fixed. The fuel filter could also be at fault. Another culprit could be the high-pressure pump.

Using the wrong fuel could also cause the engine to stall. You must know that diesel engines are compatible with diesel fuel only, so if you use a different type of fuel, you may damage various parts. A worst-case scenario would be that you may have to buy a completely new engine. Either way, fixing this problem may need you to set aside a significant amount of money. Therefore, ensure you double-check whether you’re pouring the right fuel into your vehicle.

Furthermore, compression is essential with combustion. If the engine has problems generating compression, the engine may stall. If the compression is weak, the engine timing will be off and won’t run properly. If you suspect this could be the issue, do a compression test with a compression gauge. It will help you determine which engine parts aren’t working properly.


Know that the best way to avoid car breakdowns is regular maintenance. Pre-travel maintenance checks are also worth doing before going on long journeys with your car. Things like checking your tires, battery, water, and oil are doable and won’t require much effort. Consider checking the filters and electrical connections as well, and try to buy good-quality fuel and oil. However, if you encounter problems with your engine, use the guidelines discussed here. If you’re unsure what to do, you can always contact the nearest help center.

mechanic working on engine repairs, close up