Diesel Engine Issues – The Answers May Be In The Exhaust Smoke

Diesel Engine Issues - The Answers May Be In The Exhaust Smoke
Diesel Engine Issues - The Answers May Be In The Exhaust Smoke

Diesel engine issues, are frustrating, and can be costly to repair.

Computer generated fault codes, only go a certain distance, to point you in the direction of the problem.

Consequently, finding and solving diesel engine issues, could be in the color of the exhaust smoke.

So, diesel engine issues, may keep you up at night, but, they don’t have to. Many Dealers, specialists and garages equipped with expensive and sophisticated diagnostic equipment, still seem to struggle. That can make it a process of elimination, unfortunately at your expense.

Diesel Engine Issues - The Answers May Be In The Exhaust Smoke
Visual Of Diesel Engine

The innovation of the computer generated fault diagnosis, brings new insights to the table. But, has led to a whole generation of mechanics. That, may have lost sight of the basic operating principles, of the diesel engine. Unfortunately, the fault codes, don’t always pinpoint the problem. But, they do bring up an array of codes, that could be either this or that.

This Is Actually Common, When Looking For Diesel Engine Issues

For example, you start your vehicle and are ready to take off. Then suddenly, you have diesel engine issues.  So, you take your vehicle to your local mechanic.

But, what do you think, when they tell you:

  • We have tried this, and it has not helped.
  • Sorry, there are no fault codes, so we can’t find anything wrong.

So, common rail diesels are the new hi-tech breed of diesel. And, were developed to meet, the ever increasing emission standards. Consequently, making operating pressures and temperatures, that are several times higher than older technology. Also, tolerances are much tighter, making them more susceptible, to fuel and carbon deposit issues. In addition, injectors and pumps are naturally more expensive. However, problems can, and do still melt pistons, and destroy engines.

To start with, today’s diesel engines are extremely sophisticated, and difficult to diagnose. So, I hope that the information below helps. Or, it may be just confusing you, but, at least it is something to start with.

View Of 6.7 Turbo Diesel Engine
View Of 6.7 Turbo Diesel Engine

Firstly, I will give you, the short version only. So, we will just list the most common areas, to focus on.

Here is the troubleshooting list, that might help, or just might even confuse you more:

  • Low compression
  • Low fuel pressure
  • Slow cranking speed
  • Glow plugs or relay faulty
  • Insufficient fuel supply
  • Fuel quality – contamination
  • Air – Vacuum in fuel supply, and Blocked fuel supply
  • Faulty Injectors
  • Bad high pressure pump
  • Faulty pressure regulator – sensor
  • Bad low pressure pump
  • Air intake restriction
  • Turbo problems
  • (EGR) problems
  • Injector blow–by, seat leaking
  • Cam – crank sensor
  • Injector wiring harness
  • Internal engine problems

We can generally understand some of the diesel engine issues, by the color of smoke, emitted from the exhaust. As a result, diagnosing the smoke may be, the window into your engine.

Consequently, There Are Three Basic Colors, Black, White And Blue

Black Exhaust Smoke, diesel engine issues

Black Exhaust Smoke
Black Exhaust Smoke

Consequently, this is due to a wrong air to fuel ratio. So, either the fuel system is delivering too much fuel into the engine. Or, there is not enough clean air. (oxygen ).

A few things to look for include:

  • Problems within injectors, plugged or wrong spray pattern.
  • Faulty injector pump.
  • Dirty air cleaner.
  • Turbocharger or intercooler faulty.
  • Problems within cylinder head, valves clogged up due to faulty (EGR).

White Exhaust Smoke, diesel engine issues

White Exhaust Smoke
White Exhaust Smoke

Consequently, this means that the fuel injected into the cylinder, is not burning correctly.

A few things to look for include:

Blue Exhaust Smoke, diesel engine issues

Blue Exhaust Smoke
Blue Exhaust Smoke

Consequently, the engine is most likely, burning engine oil.

A few things to look for include:

  • Worn cylinders or piston rings.
  • Faulty valves or valve stem seals.
  • Engine over full with engine oil.
  • Faulty injector pump, lift pump, letting engine oil mix with the diesel fuel.


So, if you’re in doubt about whether or not your engine is in trouble. Don’t hesitate to get it checked out. Because, most little problems, can grow into big diesel engine issues.