Heavy duty diesel engines can run for millions of kilometres with the right maintenance schedule. Simple construction and tough internal components mean that diesels are unlikely to fail all of a sudden.
But, diesels still need servicing, and the colour of the exhaust can tell you a lot about the condition of the engine. Black, white, blue or grey diesel exhaust can all indicate that something is wrong with the vehicle.
Diagnosing unusual exhaust colours can be a challenge. It’s normal for your exhaust to have a slight colouration at times, and each colour can represent a handful of different issues. In this article we’ll discuss diagnosing black, white, blue or grey smoke from your diesel exhaust.
White Smoke From Diesel Exhaust
Diesel engines may blow white exhaust.
If you live in a cold climate and your exhaust produces a thin, white smoke when you first start the vehicle, this is caused by a form of condensation. This usually isn’t a problem if the smoke goes away within a few minutes.
Thicker clouds of white smoke that don’t fade away after running the engine indicate much bigger issues.
White smoke from a diesel exhaust can be caused by:
It’s common for diesels that are blowing thick, white smoke to also run poorly. If the engine seems lumpy, sluggish or low on power, switch it off and contact your diesel mechanic. Running an engine that is blowing white smoke can cause serious damage.
Don’t Ignore an Abnormal Exhaust, Get Your Vehicle Inspected
If you’re concerned about the colour of your diesel exhaust, book an inspection with KS Mobile Diesel. KS Mobile Diesel is a mobile diesel mechanic based in Caboolture, and servicing all over the Brisbane region.
Our mobile fleet is equipped to service light and heavy trucks, Buses, trailers, earthmoving and agriculture equipment, 4WDs and much more.
Contact us today to book an appointment. We’ll come to you and provide full diagnostics, maintenance and repairs!
Blue or Grey Smoke From Diesel Exhaust When Accelerating
Blue or grey smoke when accelerating is one of the most common complaints on diesels. These two colours of exhaust smoke are actually caused by the same thing: the engine burning excessive amounts of oil.
In all engines, oil is used to lubricate internal components. Small amounts of oil are burned during normal operation. If the engine starts burning too much oil, the exhaust may look blue or grey, depending on the severity of the issue.
It’s fairly common for diesel engines to blow blue smoke in cold climates. If the smoke goes away once the engine has warmed up, there’s no need to panic. If the blue smoke persists then you need to contact a mechanic.
Blue or grey smoke from a diesel exhaust can be caused by:
Your mechanic can perform a simple compression test to determine where the problem is located. Engines that burn large amounts of oil may need to be rebuilt, or the head may need to be rebuilt. This is a large task, but rebuilt components can deliver years of trouble-free operation.
Black Smoke From Diesel Exhaust
Small amounts of black smoke are normal for diesel engines. Black smoke contains carbon particles, hence its colour. Excessive amounts of black smoke usually indicate that something is wrong with the fuel combustion system.
Black smoke from a diesel exhaust can be caused by:
If you notice black smoke coming from your diesel exhaust, put the vehicle in neutral and increase the engine speed. Watch the amount of black exhaust as the RPMs increase. While small amounts of black smoke are normal, the exhaust should be mostly colourless as the engine heats up and as you accelerate.