Checking the Cooling System For Leaks

Checking cooling system for leaks




Tools

Note Perform the leak test only on a cold engine.





1. Remove cap and attach tester.





2. Pump the cooling system up to an excess pressure of 1.3 bar. If the pressure decreases, locate the leak and remedy the fault. Check pressure relief valve(s) in the cap. Screw the tester, adapter and cap together.
Test, single-stage cap
Part number 443 121 321
1. Generate excess pressure.
2. The pressure relief valve opens and the pressure remains constant at an excess pressure of 1.3 bar, If the pressure decreases, replace the cap. The two-stage cap is the preferred version.
Test, two-stage cap
Part number 996 106 447 00
1. Generate excess pressure (stage 1)
2. The pressure relief valve opens at an excess pressure of approx. 1.4 bar; the pressure then slowly decreases again and the valve closes at 1.0 bar. If the pressure decreases further, replace the cap.
3. If the test pressure of stage 1 is maintained, test stage 2. Apply excess pressure to the pressure relief valve of stage one by pumping rapidly. The pressure relief valve of stage 2 must open at an excess pressure of approx. 1.8 bar. If the valve does not open, replace the cap.