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Diesel Engines And Blue Or White Smoke: Should You Worry?

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When a diesel engine runs efficiently, you shouldn't really see any coloured smoke from the exhaust. In certain conditions (such as driving up a steep hill), you may see a short plume of black smoke, but smoke during normal driving conditions probably points to a more serious problem. Find out what causes blue or white smoke, and find out what you need to do to deal with these problems.

Blue smoke causes

Blue smoke is a surprisingly common occurrence that can affect diesel vehicle drivers. The precise colour of the smoke can vary in shade, but some drivers may see a vivid blue plume of smoke from their exhaust.

Diesel drivers often see blue smoke from their exhausts after a cold start. As the problem generally subsides once the engine warms up, some people decide to ignore the issue, but it's important to remember that this symptom is not something you can ignore. What's more, blue smoke doesn't smell very nice, either, so you won't win popularity contests with anyone around the car when you set off.

If blue smoke appears when you start your car, it's likely that motor oil has entered the engine's combustion chamber. This shouldn't happen. If it does, the smoke suggests that you have a problem with critical engine parts. Worn or damaged cylinders, piston rings and gaskets are common problems that can cause blue smoke from a cold start.

The wrong type of engine oil can also cause blue smoke. If the oil is too thin, the lubricant can get into the combustion chamber. In turn, the oil is not thick enough to properly lubricate the engine, so the risk of damage to critical parts increases significantly. In some situations, blue smoke occurs simply because the driver has put too much oil in the engine.

White smoke causes

White smoke isn't as dirty as black smoke, nor is the problem as unusual as blue smoke, but this still isn't a symptom that diesel drivers can ignore. A thick cloud of white smoke could point to a serious mechanical issue, and you can also cause a nuisance to other drivers whose visibility you obscure.

White smoke can occur from a cold start-up or continuously while driving. The problem generally means that you have unburned fuel in your exhaust. If the problem goes away after a short time, you may have a simple problem with your piston rings, which cannot function properly due to unwanted deposits. If the problem continues all the time the engine is running, you may have a more serious issue with other critical parts.

Causes of persistent white smoke from diesel engines include:

  • Worn or faulty fuel injectors
  • Damaged engine cylinders
  • Worn head gaskets
  • A cracked engine block

Clearly, some of these issues are easier to fix than others. For example, a mechanic can replace worn injectors relatively easily, but if there's an issue with the engine block, you may face a significant repair bill. Realistically, more serious problems like this only occur because the driver continues to ignore problems for a long period, so it's essential to seek a mechanic's advice as soon as you see white smoke.

Poor-quality fuel can also cause white smoke emissions, so make sure you always choose a high-grade diesel.

Preventing serious damage

There are various precautions you can take to stop your diesel engine developing a fault that causes blue or white smoke.

Always use the right engine oil. Check your owner's manual carefully to get the details of the oil the manufacturer recommends you use. If you're uncertain, check with your dealer or mechanic first, as the wrong type of oil can wreak havoc on your engine.

Arrange a routine inspection and oil change in line with the manufacturer's recommendations. These inspections can pinpoint the early signs of a problem, and regular oil changes can avoid the wear and damage that often cause blue or white smoke. High-mileage drivers should take particular care to seek regular inspections.

Finally, never ignore any blue or white smoke coming from your exhaust. While drivers should always worry about these symptoms, the repairs you need may not cost you a fortune if you seek help straight away. For more information, contact a company like L.K. Diesel Service