Rob
I just bought a 2006 Ford Power Stroke and I am concerned about the colour of the exhaust smoke. Once the diesel engine warms up, the exhaust smoke is white. Is this normal?
Chad
Well Chad, the fact that you have noticed the exhaust smoke at all is a good thing because you can use your powers of observation as a continuous form of diagnosis.
Exhaust gases should be colourless in a normally operating diesel engine. Any coloured smoke is an indication that the engine is not running properly. So let's run through the typical colours and what they mean.
There are four engine operating conditions that show up in the colour of the exhaust smoke:
- Colourless: properly running diesel engines have no telltale signs of colour. The only noticeable change is during the warm-up cycle. Just like a gasoline engine, diesels emit a "white" steam with the exhaust. There is a difference that will make sense when I have completed the spectrum descriptions.
- Black smoke is a telltale sign that the engine is either running overloaded, has a restricted air supply, or a malfunctioning injector. The black is over-fuelling and manifests itself as black soot.
- Blue smoke is an indication that the engine's own lubricating oil is being burned. This can be caused by worn valve guides, piston rings or seals. Sometimes an over-filled crankcase will provide the oil to be burned through the process of windage. Literally, the crankshaft and connecting rods hit the top of the oil and whip it into foam that ends up on the cylinder walls eventually to burn during the combustion process. In a more rare case, the use of an overfilled oil bath air cleaner can be the source of burning oil.
- White smoke is usually a sign of water vapour that has found its way into the fuel supply or fuel that has been atomized but not burned. The water vapour may be present in the fuel or water may be leaking into the combustion chamber from the cooling system. Air in the fuel can also cause white smoke.
So Chad, back to your situation; the big difference between bad white smoke and good white smoke is the dissipation rate. Normal white steam dissipates quickly, the bad stuff is thicker or dense and it feels oily if you put your hand in it.
You haven't made any comments on the drive-ability of the truck so I'll assume that it is running normally. The best advice I can give is to run your hand through the exhaust and feel for residue. If it's only wet, you are good to go. If it's oily, sorry, but there's more work to do.