Why do cummins smoke

Topics: On-Highway Trucks. We have all seen clouds of black smoke emanating from the exhaust stacks of heavy duty diesel trucks especially when the truck is under high load or hard acceleration. The black smoke is composed primarily of elemental carbon from incomplete combustion of diesel fuel and traces of engine lubricant. The exhaust of a typical diesel engine contains elemental carbon soot , semi-volatile organic hydrocarbons, sulfates primarily sulfuric acid , and water vapor.

Elemental carbon which is black is formed for a wide range of reasons when the diesel fuel charge in the combustion cylinder is incompletely combusted. Over-fueling is the primary cause of black smoke from the exhaust of a heavy duty diesel engine.

Over-fueling can be caused by diesel fuel injector wear that enlarges the nozzle hole or erodes the injector needle and allows excess fuel to flow into the combustion chamber.

The main and ideal end products of combustion are CO2 and H2O carbon dioxide, the greenhouse gas and water. It is believed that the last step in the process is carbon monoxide the poisonous gas to carbon dioxide. This is also the slowest step by far, and when combustion conditions deteriorate some upstream bottle necking occurs in the chain of combustion reactions.

This results according to some authorities in polymerization of smaller partly burnt molecules into much larger ones, which become visible as soot, or black smoke. The oil can enter the combustion chamber for several reasons.

At cold start, blue smoke is often evident, and can reflect reduced oil control, due to fouling deposits around piston rings or cylinder glaze which is actually carbon deposited in the machined cylinder crosshatching.

These tiny grooves actually hold a film of oil, which in turn completes the seal between the combustion chamber and the oil wetted crankcase. Blue smoke should not be evident at any time, but it is worth noting, that engines with good sound compression can actually burn quite a lot of oil without evidence of blue smoke. Good compression allows oil to burn cleanly, as part of the fuel.

It is not good though! Once again, restore physical cleanliness to all components. Replace worn parts where necessary. In some situations, where the engines are pretty worn, but you just need to keep them in service, cleaning with the previously mentioned products, followed by effective additional anti-wear protection, will reduce internal stresses on all those tired components, providing extended service life.

Our AW10 Antiwear achieves this for many of our customers. Other common causes of blue or grey exhaust smoke include poor seals on piston rings, valve seals, PCV valves, injector o-rings, or turbo seals. There are a few low-cost solutions you can try to find the cause of the blue smoke and stop it from coming back. If you suspect you might be burning oil, Stiction Eliminator is an excellent place to start. It works by removing the built-up sludge and varnish created by burnt oil and lubricating your engine.

The stiction eliminator can also clean other engine components such as the oil pump, HEUI injectors, pistons and more. This high-quality oil treatment can help reduce friction in the engine, lower engine operating temperatures and make the engine run efficiently and smoothly. Stiction Eliminator belongs first on the list due to its money-back guarantee and ease of installation.

Another option you can try is to run a compression test. Many auto parts stores offer compression test units for rent, with your money back when you return the tool. You could also try replacing your PCV valves. Be careful of white smoke as it will irritate your eyes and skin. If white smoke occurs during a startup in freezing temperatures, then goes away, it usually indicates frozen deposits of soot which expanded around the rings then burned away once the engine warmed up.

Black smoke, unlike white smoke, contains a high concentration of carbon exhaust particles. The combustion of diesel fuel in the cylinders breaks down the long chain of carbon molecules to smaller and smaller molecular chains. When the exhaust leaves the engines the byproduct is a combination of carbon dioxide and water. If something goes wrong during combustion the chemical reaction taking place is not as robust, causing long tail hydrocarbons to be left completely intact and then expelled in the form of smog or soot.

Partial burning of diesel fuel results in large carbon dioxide particles as well as greenhouse gasses which contribute to air pollution. The advent of the Selective Catalytic Converter, Diesel Exhaust Fluid and Diesel Particulate Filter all helped to regenerate exhaust back into the combustion chamber to further break down particulate matter.

Diagnosing Causes of Diesel Smoke at Capital Reman Exchange Black smoke is the most common smoke color coming from a diesel engine and most likely indicates something is wrong during the combustion of the diesel fuel.