Withdrawal
1. The main purpose of the belt is to drive the camshaft (ov). If, while the engine is running, the belt breaks or jumps off, the gas distribution is disturbed, the pistons hit the valves - there will be a serious breakdown. Therefore, it is very important for the belt to be properly tensioned. Check the condition of the timing belt regularly.
2. The procedure for removing the rear timing belt cover is described as part of the procedure for removing the cylinder head in paragraph 11 of this chapter.
3. Disconnect the battery by disconnecting its negative cable (see chapter 5A). Remove the engine top cover.
4. Apply the handbrake, raise the front of the vehicle and install the jack stands. If necessary, remove the bottom protective casing of the power unit.
5. Access to the belt is possible after detaching the front panel of the body (with hood latch). Move the panel away from the body as far as possible without disconnecting the wiring and radiator hoses. To do this, first remove the front bumper as described in chapter 11, disconnect the three quick-release fasteners of the soundproofing panel, unscrew the bolts securing the air duct to the hood lock bracket and the air filter. In the left side of the radiator, disconnect the wiring braid from the fasteners. Unscrew the mounting bolts on the hood lock bracket assembly at the bottom of the body, unscrew the upper bolts that are behind the headlights. With the help of a second person, remove the entire front panel assembly and move it away from the vehicle as far as possible. To hold the panel, Audi mechanics use special template brackets, however, you can make their counterparts from a bar by cutting threads at its ends. Wrap these devices in the side members of the body.
6. Remove the accessory drive belts as described in paragraph 6. Remove the tensioner from the front of the engine using a hex wrench.
7. Remove the viscous fan coupling as described in paragraph 5 of chapter 3. It is removed with a hexagon at the back, holding it motionless with a fork tool inserted into the pulley holes - if the Audi tool is not available, it is easy to make a homemade one from a pair of steel strips fastened in the form of a coil, at the ends of which a bolt and nut are screwed.
8. Remove the small cover to the right of the outer timing belt cover, move the boost pressure control solenoid valve to the side without disconnecting the hoses.
9. Set the engine to TDC as described in paragraph 2. The procedure includes removing the valve cover and fixing the injection pump sprocket.
10. Loosen the mounting screws and remove the auxiliary belt pulley (if installed, together with A/C compressor pulley) from crankshaft sprocket (pic. 4.10). Make sure the engine TDC marks are aligned.
11. Release the upper part of the timing belt cover by unhooking the metal latches and, if necessary, unscrew the screws and remove the inserts (pic. 4.11). Remove the cover from the engine.
12. Remove the bolts and remove the lower outer timing belt cover from the cylinder block (pic. 4.12).
13. As described in paragraph 5, loosen the timing belt tension by slightly loosening the tensioner mounting nut so that it can be tilted away from the belt.
14. Find the manufacturer's mark on the belt indicating the direction of rotation of the belt. If there is no mark, apply your own with paint or a marker - do not scratch the belt.
Warning: If the belt is to be reinstalled, install it with the direction of rotation marked, otherwise wear will progress, leading to serious engine damage soon.
15. Pull the timing belt off all sprockets and remove the belt from the engine. If the belt is to be reinstalled, DO NOT BEND it too much.
Examination
16. Check the timing belt carefully for wear, delamination. cracks or decomposition of its material from trapped oil. If traces of oil on the belt are found, find the cause and eliminate it, wash off all traces of oil around the belt installation site. If there is even the slightest doubt about the suitability of the belt, its replacement will be much cheaper than a potential engine repair. The belt is replaced every 60,000 km, however, if the vehicle has less mileage, the belt should also be replaced as a preventive measure.
17. If the belt is removed for a long time, hang a warning label on the steering wheel to protect the engine from accidental starting or turning.
18. On ANN engines, the bolts securing the injection pump sprocket to the hub must be replaced after loosening. Purchase three new bolts before installing the belt. The bolts stretch when turning to the prescribed angles - they cannot be reused. After replacing the belt, Audi prescribes that it is MANDATORY to adjust the injection timing - simply installing a new belt according to the marks is not enough.
Installation
19. Make sure that the crankshaft and camshaft are set to the TDC position of the compression stroke of the first cylinder, as described in paragraph 2.
20. As described in paragraph 5, loosen the camshaft sprocket bolt by no. To hold the camshaft motionless, do not use the bar fixing it - it can be bent, the bar must be removed before loosening the bolt. Loosen the tapered seat of the sprocket by inserting a punch into the hole in the rear timing belt cover and tapping the back of the sprocket with a hammer through the punch (pic. 4.20).
21. On ANN engines, unscrew the three bolts securing the injection pump sprocket and tighten new ones (see point 18), by tightening them in this stage "by hand" (pic. 4.21). Install the outer sprocket in the center of the oblong holes.
Warning: Do not loosen the center nut, otherwise the basic setting of the injection pump may be disturbed and the assistance of an Audi/VW dealer or a diesel technician may be required.
22. Circle the timing belt under the crankshaft star.
Note: Make sure that the mark about the direction of rotation of the belt is set correctly.
23. Align the teeth of the belt with the crankshaft sprocket, circle it around the auxiliary shaft sprocket, injection pump sprocket, camshaft sprocket and tensioner pulley. Track the coincidence of the teeth of the belt with the sprockets. The top shoulder of the belt should pass under the small top pulley.
Note: This may require slight adjustment of the camshaft sprocket position. Avoid excessive bending of the belt when installing it (pic. 4.23, a, b).
24. All slack in the belt should be on the side of the tensioner pulley.
25. Inserting the tensioner pulley with bent-nose pliers into the hub holes, turn the tensioner pulley clockwise until the protrusions on the pulley and the hub match (pic. 4.25). Semi-automatic type tensioners, when the indicated protrusions are combined, the correct belt tension will be ensured.
Note: If the tensioner is turned too far clockwise, it will need to be fully loosened before a new belt tensioning operation is performed.
26. Aligning the tensioner marks, tighten the tensioner nut to the prescribed torque. Check the operation of the tensioner by pressing on the belt with your thumb and checking the discrepancy between the marks on the hub and the tensioner housing - after the belt is released, the marks should match again.
27. Remove the fixing pin from the injection pump sprocket (see paragraph 2).
28. Remove the camshaft retainer (see paragraph 2).
29. On ANN engines, tighten the new injection pump sprocket mounting bolts to an initial torque of 20 Nm, while holding the outer sprocket from turning with a suitable tool. Do not knock the installation between the sprocket sections. The final tightening of the bolts must be carried out after the injection timing of the injection pump has been set.
30. Check the installation of the camshaft and crankshaft at TDC (see paragraph 2). On ANN·motors, if the fixing pin is not inserted, temporarily loosen the three sprocket mounting bolts, move the sprocket as needed and retighten the bolts to 20 Nm.
31. As described in paragraph 5, tighten the camshaft sprocket mounting bolt to the prescribed torque, holding it with the special tool from turning.
32. Grasping the central bolt of the crankshaft sprocket with a wrench, turn the crankshaft not two full turns. Set the engine back to the TDC of the first cylinder, as described in paragraph 2. Make sure that the fixing pin can be inserted into the holes of the injection pump sprocket and the bracket.
33. Install the valve cover with a new gasket, - see paragraph 7.
34. Install the lower timing belt cover and secure it with clips and screws. Install the top cover and secure it with all fasteners.
35. Install the auxiliary shaft pulley and tighten its fastening screws to the prescribed torque. Note that the asymmetric bolt hole arrangement only allows the pulley to be installed in one position.
36. Install the boost pressure control solenoid valve and small cover to the right of the timing cover. Tighten the bolts.
37. Install the viscous fan coupling as described in chapter 3.
38. Install the tensioner on the front wall of the engine and install the auxiliary belts as described in paragraph 6.
39. Establish an arm of the lock of a cowl in an order, the return to removal.
40. Establish the lower protective casing of the power unit and lower the car. Install the engine top cover.
41. Connect the negative cable to the battery as described in chapter 5A.
42. Finally, as described in chapter 4B, check the injection timing of the injection pump.
43. On ANN engines, remove the upper timing belt cover and tighten the injection pump sprocket mounting bolts to the angles prescribed specifications. Finally, install the engine top cover.
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