Genuine 1990 Audi 100 Timing Belt

1990 Audi 100 Timing Belt Parts and Q&A

• Q: What are the steps involved in removing and replacing the toothed timing belt on 1990 Audi 100?

  A: The toothed timing belt in turn drives the camshaft and also the coolant pump though the injection pump is acted upon by another drive belt at the rear of the camshaft. The slipping or breaking of the timing belt may result in severe engine damage through the disruption of the valve timing and piston to valve contacts. It is thus important to ensure that there is accurate tensioning and periodic check-up of any wear or deterioration. To start, you have first to disconnect the battery, put on the handbrake, jack the vehicle and put it on axle stands before you remove the undershield. The second step is to take off the front bumper and front headlights, as well as removing the cable of the bonnet lock. Unscrew the crossmember and take it out and the small air-duct out of the radiator. Take the radiator out of position by taking out the radiator upper mounting bolts but do not unscrew the hoses attached and remove the radiator out of its mounts and push it forward. Disassemble auxiliary drive belt and viscous fan unit (where applicable) then the top guard of auxiliary drive belt, tensioner and spring. Unbolt the cover at the back of the engine and remove the camshaft cover in order to reach the drive belt of the injection pump. Unscrew the spring clips and take away the timing belt front upper cover and bottom outer cover. Position the engine at TDC and align the timing marks and keep the crankshaft stationary with the central bolt of vibration damper loose. Unbolt the bottom timing belt cover and take out vibration damper. In pre-1995 models, loosen the timing belt tensioner bolt and turn it clockwise to relieve tension; in the later models, it goes in an anti-clockwise direction. Noted the direction of rotation of the timing belt, then slack it off the crankshaft, camshaft and coolant pump sprockets. Check the belt in terms of contamination and wear changing it in case of need. To refit, make sure that the crankshaft and cam-shaft are in TDC and then loosen the camshaft sprocket bolt, then loop the timing belt under the crankshaft sprocket and connect with the cam-shaft and coolant pump sprockets. Move the belt across the idler and tensioner rollers and make sure that the run on the left hand side is taut. Install the belt as indicated in the model and firmly clamp the camshaft sprocket bolt and ensure that the TDC timing marks align after rotating the crankshaft. Install the lower timing belt cover, lubricate the crankshaft central sprocket bolt, and reinstall the vibration damper, screwing the bolts up to the recommended amount of torque. Re-fit fuel injection pump drive belt, timing belt covers, camshaft cover, auxiliary drive belt tensioner and viscous fan unit. Installation of the radiator and support brackets, as well as, air ducting, then install crossmember and bonnet lock. Lastly, fit the front headlights, front bumper, replace the undershield, lower the car, reconnect the negative lead of the battery and refill the cooling system in case the radiator was taken out.