Black smoke will always appear when the engine is greatly accelerated and blue smoke is
common on starting. It is necessary, therefore, to run the engine for a while at low speeds and under
loads before assessing the exhaust.
Dense black smoke means incomplete combustion of the fuel, perhaps due to overloading of the
engine or to a delivery valve at the fuel pump being stuck open and too much fuel entering the cylinder.
Grey smoke is caused by bad injection timing or dirty sprayer nozzles. Blue smoke indicates excess
lubricating oil burning in the combustion chamber. The excess oil may be due to an overfilled sump or a
faulty piston ring.
2.38. BATTERY DOES NOT CHARGE
b. Faulty electric circuits.
2.39. AIR PRESSURE
a. Does not build up.
(1) Main reservoir drain valve open.
(2) Brake pipe angle cock open.
(3) Pilot valve stuck open.
(4) Unloader valve stuck open.
(6) Faulty compressor.
b. Builds up slowly.
(1) Long train requires longer time to charge.
(3) Unloader valve stuck open.