A pressure test is performed on the cooling system to check for leaks. An adapter attaches a hand pump to the radiator cap to pressurize the system equal to the cap rating. The pressure should hold steady - if it drops, it indicates a leak. Technicians check for leaks in components like hoses, radiator, heater core, engine heads, and plugs if the pressure drops during testing.

1. Cooling
System
Pressure Test

2. TESTING THE
COOLING SYSTEM
Pressure testing the cooling system.
A typical hand-operated pressure
tester applies pressure equal to the radiator
cap pressure.
The pressure should hold; if it drops, this
indicates a leak somewhere in the cooling
system. An adapter is used to attach the
pump to the cap to determine if the radiator
can hold pressure, and release it when
pressure rises above
its maximum rated pressure setting.

3. TESTING THE COOLING SYSTEM
CAUTION: Do not pump up the pressure beyond that
specified by the vehicle manufacturer. Most systems should
not be pressurized beyond
14 psi (100 kPa). If a greater pressure is used, it may cause
the water pump, radiator, heater core, or hoses to fail.

4. TESTING THE
COOLING SYSTEM
If the cooling system is free from leaks, the pressure
should not drop. If the pressure drops, look for
evidence of leaks in the cooling system including:
1. Heater hoses
2. Radiator hoses
3. Radiator
4. Heat core
5. Cylinder head
6. Core plugs in the side of the block or cylinder head

5. REFERENCE
Duffy. E. J., (2004) Modern Automotive Technology (6 e.d.). Goodheart-Willcox Co.
Halderman. D. J., (2012) Automotive Technology: Principles, Diagnosis and Service (4th e.d.).
Pearson Education, Inc.,