There's been a lot of questions over the years about diesel smoke, and what the different colors mean. There have been some good data and input from different members. Just putting in a turbo (even with exhaust and intake changes) will often lead to white smoke. Won't hurt to run lean, but you are not getting any extra power above the help at altitude. Blue smoke usually means you need work, it is never right. I idle mine a LOT -- I'll let it idle for an hour and never worry, never cause smoke. I think my mode to put 13BT sized valve train into the 3B head (easy) made more difference than anything -- a 300 degree drop in EGT by itself. Note that a "puff" at times on a mechanical engine -- like when lugging and the flooring it -- is NOT a problem, and is normal. The mechanicals don't react like modern electronics. The things to keep in mind -- turbos only add air (O2) so they don't in themselves add power. Injectors and fuel pump add fuel which they cannot burn unless you have more O2. And all of it will get too hot if you don't have enough air flow (I did intake, 2.5" exhaust, bigger valves, injectors, fuel pump - mild - 15% increase of fuel and a 12lbs boost limit. Reliable, good economy, plenty of torque, and one of the few 40 series than will cruise all day long at 75 in 100+ degree weather and A/C on ... or sit in traffic and still be cool and fine. You have to match O2 and fuel to make the smoke "correct." Good news is unlike gassers, smoke is not terminal. On a gasser black smoke fouls plugs, white smoke is lean and creates way too much heat and knocking (our friend). So you can make changes and play -- without a lot of fear.
Maybe the mods can look at diesel smoke FAQ.
Here is the main data from the NZ link, without the hyperlinks. I think it jives with what some of the more experienced and knowledgeable folks have mentioned. What do ya'll think.
SMOKE COLOUR
Basically there are 3 types of smoke emitted from a diesel engine: black, blue and white.
Black smoke:
Black smoke is the most common emitted from diesel engines and indicates incomplete combustion of the fuel. Black smoke causes can vary widely and include ..
· Incorrect fuel injection timing
· Dirty or worn fuel injectors
· Over fuelling
· Faulty turbocharger, or turbo lag
· Faulty or dirty exhaust gas recycling (EGR) system
· Incorrect valve clearance
· Incorrect fuel to air ratio
· Dirty or restricted air cleaner systems
· Over loading the engine
· Poor fuel quality
· Cool operating temperatures
· High altitude operation
· Excessive carbon build-up in combustion and exhaust spaces
Black smoke can occur across the entire operating range, but is usually worst under full power, or during the lag before the turbocharger boosts air supply to match the fuel usage such as in the early stages of acceleration and during gear changes. Moderate turbo lag smoke is acceptable; otherwise black smoke should be hardly visible in a correctly running engine.
Blue smoke:
Blue smoke is caused by engine lubricating oil burning. The oil can enter the combustion chamber from several sources including:
· Worn valve guides, or seals
· Cylinder &/or piston ring wear
· Cylinder glaze
· Piston ring sticking
· Incorrect grade of oil .. too thin and getting past rings, or valves guides
· Fuel dilution of the oil, making it too thin.
Blue smoke is often evident at cold start, which can reflect reduced oil control due to carbon fouling deposits around the piston rings and/or cylinder glaze. Blue smoke should not be evident at any stage.
An engine may burn oil without the evidence of blue smoke, because good compression burns oil quite cleanly, however, it is not acceptable for any new engine, or engine in good internal condition to burn large amounts of lubricating oil.
White smoke:
White smoke is caused by raw, un-burnt fuel passing into the exhaust stream. Common causes include:
· Incorrect fuel injection timing
· Defective fuel injectors
· Low cylinder compression
Low cylinder compression may be caused by leaking valves, sticking piston rings, ring wear, cylinder wear, or cylinder glaze. When white smoke occurs at cold start and then disappears as the engine warms up, the most common causes are fouling deposits around piston rings and/or cylinder glazing.
Continuous evidence of white smoke indicates a mechanical defect, or incorrect fuel timing.
