Removal
1. Remove the cover bolts located on the rear of the engine to gain access to the fuel pump drive belt.
2. Remove the glow plugs to make it easier to crank the engine.
3. With the socket in place on the crankshaft pulley bolt, slowly rotate the crankshaft clockwise until the TDC timing mark on the edge of the flywheel/drive plate aligns with the timing rib on the clutch housing and the timing mark on the fuel pump sprocket aligns with the mark on the pump housing. The moment when piston #1 begins to move in the cylinder can be determined by the sound of air escaping from the #1 glow plug hole. Alternatively, remove the camshaft cover to expose the lobes of cylinder #1. When they both point upwards, piston #1 is at TDC.
Note: Due to the dynamic injection timing setting method (the pump rotates on the mount to make fine adjustments) the TDC mark on the fuel pump pulley may not line up exactly with the mark on the pump housing. In this case, make new timing marks to use when installing the drive belt.
1T engines
Note: The tensioner mechanism is equipped with brackets for the spring needed to tension the drive belt during installation. The spring is actually a special Audi tool, not available to the car enthusiast.
4. Mark the tension of the pump drive belt to facilitate its subsequent installation. Loosen the nut on the belt tensioner to loosen it. Remove the belt from the fuel pump sprockets and camshaft (see illustrations).
3D Engines
5. On 3D engines, lock the fuel pump sprocket by inserting a pin through its mounting hole into the pump housing. Lock the sprocket onto the rear end of the camshaft using a suitable tool (see Chapter 6), then unscrew the mounting bolt and remove the sprocket and drive belt. Remove the belt from the fuel pump sprocket.
Inspection
6. If the belt is contaminated with coolant or grease, find the source and correct the cause. Inspect the belt for damage and signs of wear, especially around the drive edges of its teeth. Replace the belt if there is any doubt about its condition; the cost of replacing the belt is insignificant compared to the cost of engine repairs that would be required if the belt broke while driving. The belt should also be replaced if the car has traveled the distance specified by the manufacturer since its installation.
Installation
1T engines
7. Position the tensioner with the lever facing up so that the tensioner presses on the drive belt when the spring is attached. The nut should be loosened one full turn to allow the tensioner to move freely.
8. Make sure the TDC timing marks on the flywheel/drive plate and fuel pump are still aligned
9. Install the drive belt on the camshaft and fuel pump sprockets and route it over the idler pulley and tensioner pulley. The lower run of the belt should be taut and the slack should be below the tensioner.
10. If possible, attach a special spring to the tensioner lever and tighten the drive belt. If a special spring is not available, ask an assistant to attach a spring balance to the lever and apply a pulling force of approximately 2.5 kg (see illustration). While holding the spring balance in this position, rotate the crankshaft approximately one-half turn clockwise, then tighten the tensioner nut to the tightening torque specified in the Specifications.
11. Check and, if necessary, adjust the injection timing as described in Section 3A.
12. Screw in the glow plugs, then install the drive belt cover and tighten the bolts.
3D Engines
13. Route the drive belt over the fuel pump sprocket, then place the camshaft sprocket into the belt and install it onto the shaft.
14. Insert the bolt and tighten it to 50 Nm, holding the sprocket stationary (see Chapter 6). The locking pin is still inserted into the fuel pump sprocket, so it is important not to put tension on the drive belt while tightening the bolt.
15. Loosen the bolt approximately half a turn and check that the sprocket turns freely on the camshaft.
16. Check the drive belt tension. There is a special Audi tool designed for this purpose. If the tool is not available, use the fact that the correct tension is such that the belt can be twisted by fingers only 90° at the midpoint of the run between the camshaft and fuel pump sprockets.
17. Make sure the TDC timing marks are still aligned, then tighten the camshaft sprocket bolt to Specifications while holding the sprocket stationary.
18. If the drive belt tension is incorrect, move the fuel pump bracket to the cylinder block by loosening its bolts. After completing the adjustment, tighten the bolts to the tightening torque specified in the Specifications, and then repeat the belt tensioning procedure.
19. Check and, if necessary, adjust the injection timing as described in Section FOR.
20. Screw in the glow plugs, then install the drive belt cover and tighten the bolts.