When you are operating in dirty atmospheric conditions, grease seals out dust, dirt, and water from entering bearings  and  bushings. Grease  lube  charts  are  either  mounted  on  the equipment or are in the operator’s manual. Grease lube charts  state  locations  of  grease  fittings  and  how  often the  fittings  should  be  lubricated.  Over  greasing  of equipment blows seals and the excess grease collects sand and dirt that acts as a grinding compound on the lubricated surfaces. Under greasing allows excessive wear caused by metal-to-metal contact. NOTE: Greasing  equipment  is  the  responsibility  of the  operator. A  water-resistant  grease  can  prevent  water  from entering bearings and bushing joints. The grease com- monly used on equipment is lithium-based. Lithium- based grease is water-resistant and has a wide range of operating temperatures. Care should be taken to keep grease  clean.  Always  keep  the  grease  container  covered to prevent dirt and water from contaminating it. ENGINE  COOLING  SYSTEMS All internal combustion engines are equipped with some  type  of  cooling  system  because  of  the  high temperatures  they  generate  during  operation.  The temperature in the combustion chamber during the burning of fuel is much higher than the melting point of iron. Therefore, if nothing is available to cool the engine during operation, valves burn and warp, lubricating oil breaks  down,  and  bearings  and  pistons  overheat resulting in engine seizure. At the same time, the engine must not be allowed to run too cold. An engine running cold does not burn all the fuel taken into the combustion chamber,  causing  carbon  deposits  to  form  that  reduce fuel  mileage,  increase  wear,  and  reduce  engine  power. Three functions of the cooling system provide a satisfactory temperature operating range for the engine. First, the system removes the unwanted heat. Second, it regulates the engine temperature to keep it just right during  all  operating  conditions.  Third,  when  the  engine is first started, the cooling system assists the engine in warming up to its normal operating temperature as soon as  possible. The two types of cooling methods are liquid cooling and  air  cooling.  The  liquid-cooling  system  is  the  most popular for automotive use, because it provides the most positive  cooling  and  it  maintains  an  even  engine temperature. Air cooling is used for small vehicles and equipment; however, air cooling is not used if water cooling  is  practical.  This  is  because  air-cooled  engines do not run at even temperatures and require extensive use of aluminum to dissipate heat. Other means of heat dissipation for the engine, in addition to the cooling system, are as follows: . The exhaust system dissipates as much, if not more, heat than the cooling system, although that is not its purpose. l The engine oil removes heat from the engine and dissipates it to the air from the sump. . The fuel provides some engine cooling through vaporization. . A measurable amount of heat is dissipated as the air passes over the engine. LIQUID-COOLING SYSTEM A simple liquid-cooled cooling system consists of a radiator, water pump, hoses, fan and shroud, thermostat, and a system of jackets and passages in the cylinder head and cylinder block through which the coolant circulates (fig. 1-44). Cooling of the engine parts is accomplished by keeping the coolant circulating and in contact with the  metal  surfaces  to  be  cooled.  The  pump  draws  the coolant from the bottom of the radiator, forces it through the jackets and passages, and ejects it into the upper tank on top of the radiator. The coolant then passes through a set of tubes to the bottom of the radiator from which the cooling cycle begins again. The radiator is situated in front of a fan that is driven either by the water pump or an electric motor. The fan ensures an air flow through the radiator at times when there is no vehicle motion. Radiator Most  radiators  have  two  tanks  with  a  heat exchanging core between them. The upper tank contains an outside pipe, called an  inlet, and on top is the  filler neck. Attached to the filler neck is an outlet to the overflow pipe. The  overflow  pipe  provides  an  opening from  the  radiator  for  escape  of  coolant  or  steam  if pressure in the system exceeds the regulated maximum. This  prevents  rupture  of  cooling  system  components. The lower tank contains an outside pipe that serves as the outlet for the radiator. The radiator is usually mounted in the front of the engine compartment so cool air can pass freely through the core. The outlet on the bottom radiator tank is connected to the water pump inlet. The top tank inlet of the radiator is connected to the outlet at the top of the engine. Rubber hoses and hose clamps are used to make 1-32