Peterbilt Medium Duty Trucks Operator's Manual after 1-07

Operating Instructions
Coolant (Water) Temperature Gauge
The water temperature gauge shows the temperature of the
engine coolant. Under normal operating conditions the water
temperature gauge should register between 165 and 205°F
(74 and 90°C). Under certain conditions, somewhat higher
temperatures may be acceptable. The maximum allowable
temperature is 210°F (99°C) with the cooling system pressurized,
except for certain special engines. Check the engine
manual to be sure.
Engine Overheating
Instruments and Controls
The cooling system may overheat if the coolant level is below
normal or if there is sudden loss of coolant, such as a split
hose. The system may also temporarily overheat during
severe operating conditions such as:
• Climbing a long hill on a hot day
• Stopping after high–speed driving
If the Engine Coolant Temperature (“WATER”) warning light
comes on and the audible alarm sounds showing an overheat
condition, or if you have any other reason to suspect the
engine may be overheating, DON'T TURN OFF THE
ENGINE unless the “LOW WATER” warning light also comes
on, indicating a loss of coolant. Instead, follow these steps:
Water Temperature Gauge
02580
A. Reduce engine speed or stop. When stopped, place the
transmission in Neutral and set the parking brake. See
Pages 68 and 74 for transmission shifting and parking
brake information.
B. Check to ensure that the oil pressure gauge reads normal.
C. Increase the engine speed to about one–half of full operating
speed, or 1100 to 1200 rpm, maximum.
Medium Duty (R10/06) Y53-6008 – 23 –