Tools Required

KM-471  Adapter. See Special Tools and Equipment .

The surge tank cap maintains proper pressure, protects the system from high pressure by opening a pressure valve, and protects the coolant hoses from collapsing because of a vacuum.

1. Wash any sludge from the surge tank cap and the valve seat of the vacuum pressure valve for the surge tank cap.
2. Check for any damage or deformity to the vacuum pressure valve for the surge tank cap. If any damage or deformity is found, replace the cap.
3. Install a suitable cooling system pressure tester to the cap using theKM-471  . See Special Tools and Equipment .
4. Pull the vacuum pressure valve open. If the surge tank cap does not seal properly, replace the surge tank cap.
5. Pressurize the cap to 120-160 kPa (17-23 psi).
6. Wait 10 seconds and check the pressure held by the tank cap tester.
Fig 1: View Of Cooling System Pressure Tester
Courtesy of GENERAL MOTORS CORP.
7. If the pressure held by the cooling system pressure tester falls below 80 kPa (16 psi), replace the surge tank cap.