TIAGO TIGOR CNG - SERVICE MANUAL

BRAKES 31 12. CHECK LIST FOR ENSURING SATISFACTORY FUNCTIONING OF SERVO Engine Off: Depress and release brake pedal several times to remove vacuum from the system. Depress pedal and hold with light pressure (7- 12 kg) and start engine. If servo is operative, pedal will fall slightly and then hold. Less pressure will be needed to hold pedal down, than with the engine in ‘off’ condition. If Servo is not operative disconnect the vacuum hose from the Servo non-return valve. Then with engine running, check the vacuum supply with a vacuum gauge. There should be at least 400 mm of Hg. If Servo is operative the vacuum leak test given. If vacuum supply is below 400 mm of Hg, repair the vacuum hose and vacuum fittings If the vacuum supply is 400 mm of Hg or more the replace or Servo is defective and should be replaced with new servo assembly. With new hose fitting repeat the basic test VACUUM LEAK TEST Run the engine at medium speed. Release the accelerator and turn the engine off. This builds up vacuum. Wait for 90 seconds and apply the brakes. Two or more applications should be Servo assisted. If the applications are Servo assisted, there is no vacuum leak. If the applications are not servo assisted disconnect the vacuum hose from the non-return valve. Then attach a short length of hose to the valve. Blow air through the hose. The valve is defective if. Air passes through. If the non-return valve is defective install a new non -return valve and repeat the vacuum leak test. If the non-return valve is OK, the Servo is leaking. Replace the Servo with a new kit.