Checking the cooling system (VW Passat B4)

To check the tightness of the system, install the VW 1274 testing device on the expansion tank.

Using the device, create excess pressure of 1 kgf/cm² in the cooling system. If the system is hermetically sealed, the pressure should not decrease.

To check the pressure reducing valve in the expansion tank plug, install the plug in the testing device. By creating excess pressure in the cooling system using the device, check the operation of the expansion tank plug pressure reducing valve, which should open at an excess pressure of 0.9-1.15 kgf/cm².