Thermo King MD-MT, Operator'S Manual

Page: 95 / 192

Engine Maintenance
95
Engine Speed Adjustments
Low Speed Adjustment
1. Start the unit and let it run until the engine is
warmed up.
2. Set the thermostat to make the engine run in
low speed and check the engine speed. The
engine speed should be 1625 ± 25 RPM.
3. If the engine speed is not correct, loosen the
jam nut on the low speed adjustment screw.
4. Turn the low speed adjustment screw to
change the engine speed. Turn the screw in to
increase the engine speed. Turn the screw out
to decrease the engine speed.
5. Set the engine speed at 1625 ± 25 RPM and
tighten the jam nut.
High Speed Adjustment
1. Start the unit and let it run until the engine is
warmed up.
2. Set the thermostat to make the engine run in
high speed and check the engine speed. The
engine speed should be 2425 ± 25 RPM.
3. If the engine speed is not correct, loosen the
jam nut at the end of the adjuster.
4. Unbolt the adjuster from the throttle lever and
turn to adjust the engine speed. Reinstall on
the throttle lever.
5. Set the engine speed at 2425 ± 25 RPM and
tighten the jam nut.
Injection Pump
Injection Pump Adjustments
When the diesel engine fails to maintain the
correct engine speed, check the following before
adjusting the speed:
1. Bleed air out of the fuel system. Recheck the
speed.
2. Bleed air out of the nozzles. Recheck the
speed.
3. Operation of electric transfer pump.
Make the engine speed adjustments with the
engine fully warmed up.
The MD-MT has one solenoid to control the high
speed function. The speed of the engine should be
checked with a hand tachometer, TK P/N
204-220, on the crankshaft pulley bolt or by the
use of a stroboscope tachometer, TK P/N
204-436.
Timing the Injection Pump to the
Engine
There are two different types of timing procedures
used on the TK 3.74 engine. One procedure
involves checking to make sure the cylinders are
timed correctly to each other, and the second
procedure times the injection pump correctly to
the engine. If the cylinders are not timed correctly
to each other, it is of no value to time the injection
pump to the engine because one or two of the
three cylinders would be out of time. The
individual plungers in the injection pump are
timed to each other by the use of spacers in the
pump plunger base. It is rare that an injection
pump would change individual cylinder timing
unless it had been through some type of repair
process, but if all other possible problems with a
rough running engine have been checked, and
especially if the engine’s injection pump has been
replaced or repaired recently, it may be
beneficial to check individual cylinder timing.
Because the possibility of incorrect individual
cylinder timing is so minimal, the procedure for
timing the pump to the engine will be covered
first. The procedure for individual cylinder timing
is very similar to timing the injection pump so it
will be covered last.