Radiator Cap: Testing and Inspection

NOTE: Since June 1983, a cap with increased opening pressure has been installed. It can also be installed in previously manufactured vehicles.





The spare part cap (B) is provided with a spring loaded seal and an additional rubber sealing ring and provides a better seal also on older-type expansion tanks with a possibly uneven contact surface.

On vehicles with overflow tank, a cap with higher opening pressure (1.4 bar) must be installed. (1.2 bar up to October 1986, 1.4 bar as of October 1986).

The caps with higher opening pressure ensure at least 1 bar gauge pressure in the cooling system even on older vehicles. This will provide increased protection against coolant ejection.


Checking Pressure Relief Valve:





1 Attach double connector 000 589 75 63 00 to tester 001 589 48 21 00 with the retaining clamps.
2 Place expansion tank cap on the double connector.
3 Check the opening pressure by pumping.





Checking Vacuum Valve
The vacuum valve (arrow) should rest against the rubber seal, be easily lifted and snap back upon release.