36 SEBU8121
Operation Section
Cold Weather Operation
•
Startability i
s improved.
•
Warm up time is reduced.
An electric block heater can be activated once
the engine is stopped. An effective block heater
is typically a
1250/1500 W unit. Consult your
Perkins dealer or your Perkins distributor for more
inform ation.
Idling the Engine
When idling after the engine is started in cold
weather, increase the engine rpm from 1000 to 1200
rpm. This wil
l warm up the engine more quickly.
Maintaining an elevated low idle speed for extended
periods will be easier with the installation of a hand
throttle. Th
e engine should not be “raced” in order to
speed up the warm up process.
While the en
gine is idling, the application of a light
load (parasitic load) will assist in maintaining the
minimum operating temperature. The minimum
operating
temperature is 71 °C (160 °F).
Recommend
ations for Coolant
Warm Up
W arm up an engine that has cooled below normal
operating temperatures due to inactivity. This should
be perform
ed before the engine is returned to full
operation. During operation in very cold temperature
conditions, damage to engine valve mechanisms can
result fr
om engine operation for short intervals. This
can happen if the engine is started and the engine is
stopped many times without being operated in order
to warm up
completely.
When the engine is operated below normal operating
tempera
tures, fuel and oil are not completely burned
in the combustion chamber. This fuel and oil causes
soft carbon deposits to form on the valve stems.
General
ly, the deposits do not cause problems and
the deposits are burned off during operation at
normal engine operating temperatures.
When the engine is started and the engine is stopped
many times without being operated in order to warm
up comp
letely, the carbon deposits become thicker.
This will cause the following problems:
•
Free op
eration of the valves is prevented.
•
Valves become stuck.
•
Pushrods are bent.
•
Other d
amage to valve train components can
result.
For this reason
, when the engine is started,
the engine must be operated until the coolant
temperature is 71 °C (160 °F) minimum. Carbon
deposits on th
e valve stems will be kept at a minimum
and the free operation of the valves and the valve
components will be maintained.
In addition, the engine must be thoroughly warmed in
order to keep other engine parts in better condition
and the servi
celifeoftheenginewillbegenerally
extended. Lubrication will be improved. There will be
less acid and less sludge in the oil. This will provide
longer serv
ice life for the engine bearings, the piston
rings, and other parts. However, limit unnecessary
idle time to ten minutes in order to reduce wear and
unnecessar
y fuel consumption.
Purge Valve and Insulated Heater Lines
The engine is equipped with a water temperature
regulator in order to allow the engine to reach the
correct op
erating temperature quickly. The water
temperature regulator remains in the closed position
until the jacket water coolant temperature has
reached th
e engine’s operating temperature. The
jacket water circulates from the top of the cylinder
block, to the water temperature regulator housing,
and back t
o the bottom of the cylinder block via the
bypass. The water temperature regulator allows
some flow of water and/or air to pass through the
water tem
perature regulator in order to ensure a
continuous flow of coolant within the cylinder block.
This is achieved via a small “jiggle” valve in the
water te
mperature regulator. The water temperature
regulator moves to the open position when the jacket
water coolant temperature has reached the correct
operat
ing temperature. The water temperature
regulator moves to the open position in order to allow
the passage of the coolant through the radiator to
dissip
ate excess heat.
The above procedure is good for normal engine
operat
ing conditions in temperate climates. During
periods of operations in a cold climate with a light
engine load, the coolant must bypass the radiator in
order
to help prevent excessive cooling of the engine.
Coolant that passes through the radiator must be
minimized in order to maintain the engine operating
tempe
rature in cold weather.
Excessive cooling of the engine can be prevented
by a v
alve that allows unnecessary coolant flow to
be diverted from the water temperature regulator
and back to the bottom of the engine block without
pass
ing through the radiator.
Note: Perkins discourages the use of all airflow
rest
riction devices such as radiator shutters.
Restriction of the airflow can result in the following:
high exhaust temperatures, power loss, excessive
fan
usage, and reduction in fuel economy.
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