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 operators 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
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
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
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
. A measurable amount of heat is dissipated as the
air passes over the engine.
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.
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