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Diesel Engines | Common Problems And Maintenance Tips

Diesel Engines | Common Problems And Maintenance Tips

Diesel is cheap compared to other fuels. A car with a diesel engine is therefore economical and gives you better mileage at the same time. But that’s not to say that diesel engines are invincible. Diesel engines have their share of problems. If they are not properly maintained, they can develop several problems, either internal or external. But do you know what to do when you start experiencing problems with your diesel engine? It can be a daunting task, especially when you are not familiar with diesel engines. This guide will help you understand common diesel engine problems so that you can be aware and prepared when your car’s diesel develops a problem.

  1. Engine overheating

Overheating is probably the biggest problem faced by diesel engines. Pushing the engine too hard is a major cause of overheating. It can result in other problems, which include swelling, distorting or breaking of cylinder heads, pistons expanding, damage to crankshaft and bearings, among other issues.

Apart from pressing the engine too hard, overheating can be caused by other things – anything that interferes with the working of the cooling system causes overheating. Causes of diesel engine overheating include:

  • Coolant leaks – this is the biggest cause of overheating and is easy to notice. Excess bubbles than normal and low coolant levels are signs of leaking coolant. Excess heat causes the cylinder head to expand, and as a result, the gasket cannot seal the coolant as it should. If this happens, it can only be fixed by a professional.
  • Clogged diesel injectors – leaks and clogs in your diesel injector can be the cause of overheating. When the injection system can’t release fuel as it should, the engine works much harder, leading to overheating.
  • Faulty cooling fan – a damaged cooling fan can cause the engine to overheat—a faulty cooling fan results from electrical problems.
  • Damaged thermostat – a thermostat prevents the engine from overheating. It has a valve that opens and closes to regulate engine temperatures. If it’s damaged, it can’t sense when the engine is overheating and hence can’t initiate cooling responses.
  1. Engine oil oxidation

If you rarely use your car or you don’t use it at all in a certain season, your diesel engine may develop problems. What happens is that when air gets into the oil, it creates bubbles that interfere with lubrication and ruin everything that requires lubrication. Also, these air bubbles can rupture the thin oil layers between moving parts, which can result in rusting and friction. In turn, this results in a faltering or damaged engine or engine components failure.

Technically, when oil oxidation occurs, the oil is not dirty and has not completed its life. However, its chemistry has been altered and therefore, should be changed after the idle period.

  1. Humidity reactions

Water can be dangerous when it gets into the combustion system. In fact, when water gets into any part of the engine where it is not supposed to be, it can lead to serious problems. It is one of the most harmful elements if it gets in contact with lubricants. Water damages additives and increases oil oxidation leading to lubrication problems and serious rust between moving parts. The engine can even knock.

But how can water enter the system? When a diesel-engine vehicle is parked in a humid environment for quite some time, hydration starts working, and water can enter the oil storage.

  1. Black exhaust

A black exhaust is not really a problem but rather an indication of other problems. Have you ever tailgated a diesel truck and noticed that they produce more smoke than other trucks? It’s normal for diesel trucks to exhibit more smoke than other vehicles. However, if it produces excessive black exhaust, that’s a sign of an engine problem. The problem with this is that you may be slapped with hefty fines for not observing the clean air ordinance. Too much black smoke can be a result of a faulty injector pump, injector, turbocharger, EGR valve, or air filter.

  1. Noise

Normally, diesel engines are louder than petrol engines. However, inconsistent sound or distinct knocking in the engine can be a sign of other problems. It may be a faulty fuel injector or an issue with the compression balance. These issues can reduce the performance of the engine. If you hear any strange noise, it wise to have your engine checked by a professional.

  1. Contaminated fuel

Diesel is more viscous compared to other fuels. As such, diesel can easily be contaminated. Common diesel contaminants include dilution, water, soot, and glycol. These contaminants are dangerous. If any of them enter the fuel pump or injector, it can cause major problems and engine disruption.

  1. Faulty glow plug

Unlike petrol-powered engines, diesel-powered cars don’t use spark plugs to ignite the fuel-air mixture. Instead, diesel engines use glow plugs. If a glow plug is damaged, it becomes impossible for the engine to start, especially in cold weather.

  1. Hard starting

Sometimes your diesel engine may fail to start a couple of times before finally starting. This is particularly so during the cold season. You see, unlike petrol engines that use electric wiring or spark plugs to start combustion, diesel engines use air compression. Hard starting is a sign of low compression or fuel delivery problems. It’s a common problem during winter. But if the engine is taking unusually long and not lighting up, there may be another underlying issue. You should have it checked by a professional engine mechanic to keep everything smooth and safe.

  1. Lack of power

Did you know that diesel engines are more powerful and torque motors than petrol engines? Well, now, you do. That is why most heavy machinery uses diesel engines. But sometimes the diesel engine may not produce enough power as it should. Normally, you will notice a lack of power when starting the engine or when accelerating. Lack of power can be as a result of various issues including:

  • Dirty oil filters
  • Faulty fuel injectors
  • Clogged fuel delivery lines
  • Lower or excessive lubrication
  • Loose throttle linkage

Important Diesel engine maintenance tips

If you want your diesel engine to keep performing at its best, and extend its life span, check out the following engine maintenance tips.

  1. Keep your engine clean

Diesel engines have a longer lifespan compared to petrol engines and may benefit from regular cleaning. The more you drive, the more soot, dust, and dirt collect on your car’s engine. This shortens the lifespan of the engine components and reduces its fuel efficiency. Needless to say, keeping your truck and diesel engine clean is important.

Additionally, keeping your engine clean makes it easy for you or your mechanic to notice issues before they result in bigger problems. For instance, on a clean engine, you can notice oil leaks, coolant leaks, and broken hoses. Also, dirty engine components such as intercoolers and radiators are going to affect the performance of your diesel engine. But you can prevent this by cleaning your diesel engine frequently.

  1. Keep an eye on engine fluids

Without engine oil, your car wouldn’t be able to roll. In fact, it would die a natural death. Oil is very important as it lubricates the moving parts of the engine. Over time, engine oil becomes contaminated and acidic and should be changed regularly. Failure to change the engine oil regularly reduces the performance of the diesel engine and lifespan.

The coolant is also important, and you should keep an eye on it as well. Keeping your coolant balanced with the proper chemicals and at the recommended levels prevents the engine from overheating.

  1. Change air filters regularly

A dirty air filter can ‘choke’ your engine forcing the engine to work harder to maintain a certain speed or accelerate. This leads to higher fuel consumption than normal. A clean air filter ensures your engine is ‘breathing’ clean air. Inspect your air filter from time to time and replace it when necessary.

  1. Change oil and fuel filters regularly

Oil filters remove dirt particles that can cause wear and damage to an engine. Ensure you replace your oil filters every time you change your engine oil.

Fuel filters need to be replaced as well to ensure clean fuel flow. Clogged fuel filters restrict fuel from flowing to your engine. In turn, this leads to reduced engine performance. The engine won’t start when the fuel filters are completely clogged. Most modern diesel engines have two fuel filters, and they should both be replaced regularly, normally after every 15k miles.

  1. Monitor and take care of your engine’s radiator

The radiator disperses heat from the engine into the air. This helps to keep the engine cool. When in operation, diesel engines produce a lot of heat, and a faulty radiator reduces heat transfer. In turn, this leads to overheating.

Proper maintenance of the cooling component is essential. Typical coolant maintenance includes coolant testing, cleaning the radiator, and sometimes replacing it when necessary.


Your car makes life easy and convenient for you. Keep it performing at its best by taking good care of its diesel engine. Fix faulty engine components and replace them when necessary. Check out Goldfarb INC for the best diesel engine components.