Genuine Audi 100 Thermostat

Audi 100 Thermostat Parts and Q&A

• Thermostat
  069-121-113
  Q: How to remove and test a thermostat on Audi 100?

  A:

  All 4-cylinder engines are fitted with electrically operated cooling fan(s), and 5-cylinder engines have the main fan driven by the auxiliary drivebelt via viscous coupling with any auxiliary fan being electrically powered. The supply of the cooling fans is carried by the ignition switch and a fuse and it is completed by the cooling fan thermostatic switch on the left side of the radiator. When a fan is switched off, the engine must be operated until it has reached normal working temperature, and then it should be left to idle, the fan should come on shortly after that. Otherwise, the ignition must be turned off and the wiring plug between the cooling fan switch must be taken out. One way of finding out whether the switch is faulty is to try to bridge the relevant contacts in the wiring plug with a spare wire with the ignition on. In case the fan now remains inoperative, there is need to test battery voltage at the feed wire to the switch and continuity between the switch earth terminal and a good earth point on the body. In the event both the switching and wiring are operable, it is possible that the actual motor is faulty and this can be checked by connecting a 12 volt supply to the motor itself. To be able to remove the radiator, it is necessary to loosen the retaining bolts of the fan shroud assembly then unclip the motor wiring and undo the retaining nuts to separate the motor assembly and the shroud. In case of a defective motor, the whole unit will have to be replaced. To refit, the motor assembly can be supported to the shroud, then the motor wiring need to be well routed then its shroud assembly must be reattached to the radiator and attached. In 5-cylinder engines, the operation of the viscous coupling is physically verified to exclude the presence of fluid leakage and damage to the fan blades, and the fan should freely rotate at room temperature and clamp together during the hot engine operation. To detach the two, the locating sleeves of the bonnet release cable will have to be disconnected, and the connecting bolts of the radiator upper mounting brackets will have to be taken out. The alignment marks are to be made, and then the crossmember is supposed to be placed over the radiator. The coupling is unscrewed off the drive pulley with an open ended spanner leaving the drive pulley in place with a peg spanner. Then the fan and coupling assembly is manipulated out. To refit, it is important that the fan blade is fitted to the coupling in the right way and then the assembly is fitted to the drive pulley and tightened to the required torque. The radiator upper mounting brackets and bonnet locking crossmember are then moved back to its original position and all components should be firmly tightened and the bonnet release cable guides re-clipped.