- Check valve seat of reservoir tank cap.

- Check if valve seat (A) is swollen to the extent that the edge of the metal plunger (B) cannot be seen when watching it vertically from the top.

- Check if valve seat has no soil and damage.

- Pull negative-pressure valve to open it, and check that it close completely when released.

- Check that there is no dirt or damage on the valve seat of reservoir tank cap negative-pressure valve.

- Check that there are no unusualness in the opening and closing conditions of negative-pressure valve.

- Check reservoir tank cap relief pressure.

- When connecting reservoir tank cap to the radiator cap tester (commercial service tool) and the radiator cap tester adapter (commercial service tool) (A), apply engine coolant to the cap seal surface.

  Standard and limit | : Refer to Radiator.

- Replace reservoir tank cap if there is an unusualness related to the above three.

■ CAUTION ■
When installing reservoir tank cap, thoroughly wipe out the reservoir tank filler neck to remove any waxy residue or foreign material.