Radiator Cap and Radiator Check (VW Sharan 1)

The cooling system operates under pressure. The radiator cap has a built-in spring, which is selected in such a way that the cap gasket closes the cooling system circuit and opens it if the pressure inside the cooling system rises to 1.4-1.8 bar [140-180 kPa]. The pressure inside the cooling system increases due to the expansion of the coolant, which leads to an increase in the boiling point.

A radiator pump is used to check the radiator cap. The procedure is similar to that described for a gasoline engine. Using a radiator pump, you can check the cooling system for coolant leaks.

The original information is posted on the website: VWmanual