takes longer than 3 to 5 minutes to disappear a problem exist. The problems white smoke may indicate are as follows:

Low cylinder compression from worn rings

Scored piston or liner

Valve seating problems

Water leaking into the combustion chamber

Faulty injectors

Use of a low cetane diesel fuel.

Black or gray smoke generally is caused by the same conditions - the difference between the colors being one of opacity or denseness of smoke. Black or gray smoke should be checked with the engine at operating temperature of 160F. Abnormal amounts of exhaust smoke emission is an indication that the engine is not operating correctly, resulting in a lack of power, as well as decreased fuel economy. Excessive black or gray exhaust smoke is caused by the following:

Improper grade of diesel fuel

Air starvation

High exhaust back pressure

Incorrect fuel injection timing

Faulty injection pump

Incorrect valve adjustment clearances

Faulty nozzles or injectors

Faulty automatic timing advance unit

Blue smoke is attributed to oil entering the combustion chamber and being burned or blown through the cylinder and burned in the exhaust manifold or turbocharger. Remember always check the simplest things first, such as too much oil in the crankcase or a plugged crankcase ventilation breather. The more serious problems that can cause blue smoke are as follows:

Worn valve guides

Worn piston rings

Worn cylinder walls

Scored pistons or cylinder walls

Broken rings

Turbocharger seal leakage

Glazed cylinder liner walls due to use of the wrong type of oil

NOTE

With the engine stopped, the condition of the pistons, rings, and liners on a two-stroke cycle Detroit diesel engine can be checked visually by removing an air box inspection cover on the side of the engine block and accessing the components through the cylinder liner ports.

QUICK INJECTOR MISFIRE CHECK

Listed below are several quick and acceptable checks that can be performed on a running engine to determine if one or more injectors are at fault on any type of engine.

On four-stroke-cycle engines with a high-pressure in-line pump or distributor system, such as Caterpillar and Roosa Master, you can loosen off one injector fuel line, one at a time, about one-half turn as you hold a rag around it while noting if there is any change in the operating sound of the engine. If the injector is firing properly, there should be a positive change to the sound and rpm of the engine when you loosen the line, since it prevents the delivery of fuel to the cylinder. On an engine with the PT fuel system, a cylinder misfire can be checked by running the engine to a minimum of 160F, removing the rocker covers, then installing a rocker lever actuator over an injector rocker lever. Hold the injector plunger down while the engine is running at low idle. This will stop the fuel flow to that injector. If the engine speed decreases, the injector is good. If the engine rpm does not decrease, replace the injector.

On the two-stroke-cycle nonelectronic Detroit diesel engines, you can remove the rocker cover, then using a large screwdriver push and hold down the injector follower while the engine is idling. This action is like shorting out a spark plug on a gasoline engine, since it prevents fuel from being injected into the combustion chamber. If there is no change to the sound and speed of the engine, the injector is not firing. There