Minimum Oil Pressure
*
Engine Model
At Idle Speed:
psi (kPa)
At Rated RPM:
psi (kPa)
Caterpillar
10–20 (69–138)
30–45 (207–310)
Cummins
15 (103)
35 (241)
Detroit
14 (97)
55 (350)
Mercedes-Benz
7 (50)
36 (250)
*
Pressures apply with the engine at operating temperature. Oil pressure
may be higher on a cold engine. Observe and record pressures when the
engine is new to create a guide for checking engine condition.
Table 2.4, Minimum Engine Oil Pressure
Engine Oil Temperature Gauge
NOTICE
A sudden increase in oil temperature that is not
caused by a load increase may indicate mechani-
cal failure. Bring the vehicle to a safe stop and
investigate the cause to prevent further damage.
Do not operate the engine until the cause has
been determined and corrected.
During normal operation, the optional engine oil tem-
perature gauge should read:
•
190 to 220°F (88 to 104°C) for Caterpillar en-
gines;
•
200 to 260°F (93 to 126°C) for Detroit and
Cummins engines
•
177 to 203°F (81 to 95°C) for Mercedes-Benz
engines
Under heavy loads, such as when climbing steep
grades, temperatures that exceed the normal oil tem-
perature range for a short period are not unusual. If
the temperature returns to normal when the load de-
creases, there is no problem.
Fuel Gauge
The fuel gauge indicates the level of fuel in the fuel
tank(s). A single fuel gauge is standard. If equipped
with an optional second fuel tank, each fuel tank
level is indicated on a separate gauge.
Primary and Secondary Air Pressure
Gauges
WARNING
If air pressure falls below minimum pressure, the
braking ability of the vehicle will be limited. Slow
the vehicle down and bring it to a gradual stop.
Do not attempt to move the vehicle until air pres-
sure has risen above the minimum level. Moving
a vehicle without adequate braking power could
cause an accident resulting in personal injury or
death.
Air pressure gauges register the pressure in the pri-
mary and secondary air systems. Normal pressure,
with the engine running, is 100 to 120 psi (689 to
827 kPa) in both systems.
A low-air-pressure warning light and audible alert,
connected to both the primary and secondary sys-
tems, activate when air pressure in either system
drops below 64 to 76 psi (441 to 524 kPa).
When the engine is started, the warning light and
audible warning remain on until air pressure in both
systems exceeds minimum pressure.
Pyrometer
A pyrometer registers the exhaust temperature near
the turbocharger. Variations in engine load can cause
exhaust temperatures to vary. If the pyrometer read-
ing shows that exhaust temperature exceeds normal,
reduce fuel to the engine until the exhaust tempera-
ture is reduced. Shift to a lower gear if the engine is
overloaded.
Speedometer
The speedometer registers speed in both miles per
hour (mph) and kilometers per hour (km/h).
Tachometer
The tachometer indicates engine speed in revolutions
per minute (rpm) and serves as a guide for shifting
the transmission and keeping the engine in the ap-
propriate rpm range. For low idle and rated rpm, see
the engine identification plate.
Instruments and Controls Identification
2.17
