Thermo King SB-III 30 SR+, Manual

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Engine Maintenance (Rev. 04/02)
36
NOTE: If an engine runs with air trapped in the block, the
engine may be damaged. The high water temperature
switch may not protect an engine that has air trapped in
the block, because the high water temperature switch is
designed to protect an engine from overheating due to fail-
ures in the cooling system.
1. Loosen the plug on the back of the water pump below
the thermostat cover until coolant comes out of the plug
fitting.
2. Tighten the plug.
3. Pour coolant into the system until it appears to be full.
4. Make sure that the amount of coolant that goes back
into the system is approximately equal to the amount of
coolant that came out of the system.
5. Start the unit on low speed, let it run for a minute, and
then shut it off.
6. Check the coolant level and add coolant if necessary.
7. Repeat steps 5 and 6 until the coolant level stabilizes.
Engine Thermostat
For the best engine operation, use a 180 F (82 C) thermostat
year-round.
Engine Fuel System
The TK 486 engine is a direct injection diesel that uses an
in-line injection pump.
The components of the fuel system are:
1. Fuel tank
2. Prefilter
3. Fuel filter/water separator
4. Priming pump
5. Fuel transfer pump
6. Injection pump
7. Injection nozzles
The priming pump is used to manually draw fuel from the
tank up to the fuel pump if the unit should run out of fuel.
Operation
Fuel is drawn from the fuel tank and through the prefilter by
the fuel transfer pump. The fuel transfer pump delivers fuel
to the fuel filter/water separator. Two orifices in the filter
head control the pressure in the fuel system by allowing a
certain amount of fuel to return to the tank. One orifice is
located in the center of the filter head. It bleeds off water.
The other orifice is located off-center on the filter head. It
bleeds off air. Filtered fuel passes through a line from the
outlet fitting on the filter base to the injection pump.
The injection pump plungers are activated by a gear driven
injection pump camshaft. The governor sleeve and weight
assembly is mounted on the end of the pump camshaft. The
governor’s speed requirements are relayed to the injection
pump through a linkage arrangement located in the rear
cover. The injection pump raises the pressure of the fuel and
meters the correct amount of fuel to the nozzle at the correct
time. The increased fuel pressure will lift the spring loaded
nozzle to admit fuel into the combustion chamber.
Injection pump leakage, injection nozzle overflow and
excess fuel from the fuel filter orifice are then all sent back
to the fuel tank in the return line.
Maintenance
The injection pump and fuel transfer pump are relatively
trouble-free and if properly maintained will usually not
require major service repairs between engine overhauls.
Contamination is the most common cause of fuel system
problems. Therefore, to ensure best operating results, the
fuel must be clean and fuel tanks must be free of contami-
nants. Change the fuel filter/water separator regularly and
clean the prefilter on the inlet side of the fuel transfer pump.