(b) determining whether it’s one or all cylinders, the next step is to determine why. White smoke means one or more fueled, but misfiring cylinders, and usually accompanies cold starts (in a warm engine it may indicate low compression). Black smoke is the sooty residue of partially burned (high HC’s) fuel, normally present during hard acceleration. Blue, blue-white, or results from lube-oil combustion. (ON #170) BLACK or DARK GRAY SMOKE Symptom Probable cause Remedial action Smokes under load, especially at high and medium speed. Engine quieter than normal. Injector pump timing retarded. Set timing. Smokes load, especially at low and medium speed. Engine noisier than normal. Injector pump timing advanced. Set timing. Smokes load at all speeds, but most apparent at low and medium speeds. Engine may be difficult to start. Weak cylinder compression. Repair engine. Smokes under load, especially at high speed. Restricted air cleaner. Clean / replace air filter element. Smokes under load, noticeable loss of power. Turbocharger malfunction. Check boost pressure. Smokes under load, especially at high and medium speeds. Power may be down. Dirty injector, nozzle (s). Clean/replace injectors. Smokes load, especially at low and medium speeds. Power may be down. Clogged / restricted fuel lines. Clean/replace fuel lines. Puffs of black smoke, sometimes with blue or white Sticking injectors. Repair/replace injectors.
e. Oil Filters. (1) Purpose. The oil filter removes most of the impurities that have been picked up by the oil as it is circulated through the engine. The filter is mounted outside of the engine and is designed to be replaceable readily. (ON SLIDE #194) (2) Filter Configurations. There are two basic filter element configurations: the cartridge type and the sealed canister type. (a) The cartridge-type filter element fits into a permanent metal container. Oil is pumped under pressure into the container, where it passes from the outside of the filter element to the center. From here the oil exits the container. The element is changed easily by removing the cover from the container when this type of filter is used. (b) The sealed canister-type filter element is completely self-contained, consisting of an integral metal container and filter element. Oil is pumped into the container on the outside of the filter element. The oil then passes through the filter medium to the center of the element, where it exits the container. This type of filter is screwed onto its base and is removed by spinning it off. (3) Filter Medium Materials. (a) Cotton waste or resin-treated paper are the two most popular filter mediums. They are held in place by sandwiching them between two perforated metal sheets. (b) Some heavy-duty applications use layers of metal that are thinly spaced apart. Foreign matter is strained out as the oil passes between the metal layers. (ON SLIDE #195) (4) Filter System Configuration. The full-flow system is the most popular in current engine design. All oil in a full-flow
combustion without harmful results. The temperature in the combustion chamber during the burning of the fuel is well above the melting point of iron. Therefore, if nothing is done to cool the engine during operation, valves will burn and warp, lubricating oil will thin and break down, and bearings and pistons will overheat, resulting in engine seizure. (ON #300) Heat is moved from hot spots in the engine in the following ways. (1) Conduction. Heat is a form of energy, and when it comes into contact with matter it makes the atoms and molecules move. Once atoms or molecules are moving, they collide with other atoms or molecules, making them move too. In this way, the heat is transferred through matter. (2) Convection. Convection occurs when a substance that can flow, like water or air is heated. When this medium is heated it becomes less dense (lighter) and rises. As it rises it forces the surrounding medium down and closer to the heat source. This sets up a circular heating and cooling motion of the fluid medium. (3) Radiation. Radiation happens when heat as energy waves, called infrared waves, directly from its source to something else. This is how the heat gets from the Sun to the Earth. All hot things radiate heat to cooler things. When the heat waves hit the cooler material, they make the molecules of the cooler object speed up. When the molecules of that material speed up, the object becomes hotter. (ON SLIDE #301) (4)There are other sources of heat dissipation for the engine in addition to the cooling system. (a) The exhaust system dissipates as much, if not more, heat than the cooling system, although that is not its purpose. (b) The engine oil removes heat from the engine and dissipates it to the air from the sump or oil cooler. (c) A measurable amount of heat is dissipated to the air through radiation from the engine. (ON SLIDE #302) b. Air Cooled Engines.