Checking low-temperature cooling system for watertightness
WARNING:
Hot surfaces.
Risk of burning!
Risk of burning!
- Perform all work only on components that have cooled down.
- Loosen sealing cap (1).
- Attach the special tool 0 494 418 (17 0 101) with the special tools 0 494 419 (17 0 102) and 0 494 426 (17 0 109) from the set of special tools 0 494 417 (17 0 100).
- Build up excess pressure and wait for approximately 2 minutes.
TECHNICAL DATA - PRESSURE SPECIFICATION
| Opening pressure of sealing cap of low-temperature coolant circuit | |
| Pressure relief valve opens when the pressure exceeds the ambient pressure. | min. 1.4 bar |
| Electric changeover valve must open at latest when the pressure is lower than the ambient pressure | max. 0.1 bar |
| Test pressure for cooling system (gauge pressure) | 1.5 bar |
NOTE:
TECHNICAL INFORMATION
If the described test step is not completed successfully: repeat test step twice. Only replace the sealing cap after three tests with an incorrect opening pressure.
When driving at high ambient temperatures, the design may cause the pressure relief valve in the sealing cap to open slightly and air to leakage together with dissolved coolant. This coolant vapor condenses on the surface of the coolant expansion tank and leaves traces of coolant when the vehicle has cooled down. These traces of coolant do not indicate whether the sealing cap is defective or not.
Leakage coolant vapors when the vehicle is at standstill may cause the pressure relief valve to stick to the sealing cap. This may cause an incorrect opening pressure.
If the described test step is not completed successfully: repeat test step twice. Only replace the sealing cap after three tests with an incorrect opening pressure.
When driving at high ambient temperatures, the design may cause the pressure relief valve in the sealing cap to open slightly and air to leakage together with dissolved coolant. This coolant vapor condenses on the surface of the coolant expansion tank and leaves traces of coolant when the vehicle has cooled down. These traces of coolant do not indicate whether the sealing cap is defective or not.
Leakage coolant vapors when the vehicle is at standstill may cause the pressure relief valve to stick to the sealing cap. This may cause an incorrect opening pressure.
- Screw on sealing cap (1) on special tool 0 495 889 (17 0 115) from the set of special tools 0 494 417 (17 0 100).
- Build up the pressure with special tools 0 494 418 (17 0 101) and 0 494 419 (17 0 102) from the set of special tools 0 494 417 (17 0 100).
- Opening pressure of sealing cap of low temperature coolant circuit
TECHNICAL DATA - PRESSURE SPECIFICATION
| Observe on the pressure tester when the opening pressure has been reached. | |
| Pressure relief valve opens when the pressure exceeds the ambient pressure. | min. 1.4 bar |
| Electric changeover valve must open at latest when the pressure is lower than the ambient pressure | max. 0.1 bar |
| Test pressure for cooling system (gauge pressure) | 1.5 bar |
- Close sealing cap (1).