What this test proves

Locate coolant leakage with a controlled static-pressure test. A static pass does not rule out a hot or load-dependent leak.

Tools

  • Cooling-system pressure pump and correct adapter
  • OEM test pressure and hold time

Preparation and precautions

  • Allow the system to cool fully before opening. Never remove a hot pressurized cap.
  • Identify the correct cooling circuit; multi-loop and EV systems may require special access or valve commands.

Connections

  • Fit the approved adapter at the specified filler or expansion-tank connection with the correct seal.

Equipment settings

  • Use the OEM test pressure, never exceed the applicable system/tool limit. Do not assume the cap rating is always the prescribed test pressure.

Test sequence

  1. Inspect coolant level and obvious leaks cold.
  2. Pump gradually to the specified pressure.
  3. Observe pressure over the specified interval and inspect approved accessible areas.
  4. Check tester sealing before interpreting decay.
  5. Release pressure through the tester before removing it.

Expected signal / readings

Pressure should hold within the specified allowance. Temperature changes and tester leakage affect the reading.

Interpreting results

  • Visible leakage identifies a location; pressure decay without visible leakage requires further investigation.
  • A cold static test may miss combustion-pressure or thermal leaks.

Common mistakes

  • Opening a hot cap
  • Overpressurizing
  • Declaring a head gasket failed from gauge decay alone