Pressure Caps; Water (Coolant) Pump - Dodge D250 1990 Service Manual

Cooling System
DODGE Turbo Diesel
Cooling System Malfunctions - Diagnosis
Page 7-5
Pressure Caps
The system is designed to use a pressure cap to prevent
boiling of the coolant.
An incorrect or malfunctioning cap can result in the loss of
coolant and the engine running hot.
The cap specified for this system is:
System
110°C [230°F]
Cap
103kPa[l5PSI]
Air in the coolant can result In loss from the overflow when the [^jS j
aerated coolant is hot. The heated air expands, increasing the
pressure in the system causing the cap to open.
Similarly, coolant can be displaced through the overflow if the
head gasket leaks compression gasses to the coolant system.
o
>
1
a
The operating pressure of the coolant system and the
lubricating system can result in the mixing of the fluids if there
is a ieak between the systems: head gasket, oil cooler, etc.
(refer to the Lubricating System).
Note: Transmission oil can also leak into the coolant through a
faulty transmission oil cooler.
Water (Coolant) Pump
The water pump pulls coolant from the bottom of the radiator
and pumps it through the engine back to the top of the radiator
for cooling. Reduced or Interrupted flow will result in the engine
running hot.