Checking pressure relief valve in sealing cap
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NOTE:
While the driving at high ambient temperatures, the design may cause the pressure relief valve in the sealing cap to open slightly and air together with dissolved coolant to escape. This coolant vapor condenses on the surface of the expansion tank and leaves toes when the vehicle has cooled down. These toes do not indicate whether the sealing cap is defective or not. When the vehicle has been parked up for an extended period of time, the residual escaping coolant can cause the pressure relief valve in the sealing cap to stick; therefore check the sealing cap again 2 to 3 times.
Replace the sealing cap only after you have checked three times and there is an incorrect opening pressure.
Screw sealing cap (1) onto special tool 17 0 114.
Build up pressure with special tool (hand pump) 17 0 101; observe pressure gauge to ascertain when opening pressure is achieved.