If only the fuel injection start is to be checked/adjusted, all work operations must be performed except for removing the timing belt.
Visual inspection of the timing belt
Remove the timing belt cover and inspect the belt. The belt should not have the following damage:
- foundation cracks (cracks, frame failure, cross-section failure);
- stratification (cover layer, tourniquet);
- local rupture at the base;
- fringe of the tourniquet;
- lateral wear (wear, fringing, hardening of side surfaces - glassy sidewalls, surface cracks);
- traces of oil and grease.
Removal
Remove the upper timing belt cover.
Mark the direction of movement of the toothed belt with an arrow using chalk so that this direction is maintained when installing the belt later. For a turbocharged diesel engine, press the tension roller cover with a screwdriver and, turning the SW13 socket wrench in the direction of the arrow, loosen the tension of the roller. For other engines, loosen and remove the V-belt.
Remove the V-belt pulley and the lower timing belt cover.
Set the crankshaft to the TDC position for cylinder 1. To do this, shift the gearbox to neutral and, using a wrench with a replaceable socket head, turn the crankshaft by the central bolt securing the belt pulley until it reaches the TDC position for cylinder 1 (arrow).
The crankshaft is at TDC for cylinder 1 when both camshaft lobes for that cylinder are pointing upward.
Lock the camshaft in this position using the 2065A adjustment ruler. If this special device is not available, make one in accordance with Figure V-1017.
Insert the adjusting ruler into the groove of the camshaft. The adjusting ruler (VW 2065A) has a protrusion that enters the groove and prevents the camshaft from turning.
Align the adjusting ruler parallel to the cylinder head. To do this, turn the locked camshaft so that one end of the adjusting ruler rests against the cylinder head. Measure the resulting gap using feeler gauges from the other end of the ruler. Insert a feeler gauge of half the measured gap between the adjusting ruler and the cylinder head. Then turn the camshaft so that the adjusting ruler rests on the inserted feeler gauge. Insert a second feeler gauge of the same thickness between the adjusting ruler and the cylinder head from the other end of the ruler.
Now it is necessary to insert the locking pin 2064 into the holes of the fuel injection pump gear wheel and the fuel injection pump bracket. The pin fixes the position of the fuel injection pump gear wheel. You can make the pin yourself in accordance with Figure V-1017.
Note: 75hp engine with 10/94 (AAZ) requires 3359 locking pin.
If the pin does not fit into the hole in the fuel injection pump bracket, the valve timing must be adjusted again.
75hp engine with 10/94 (AAZ): loosen 3 bolts securing the injection pump gear.
Loosen the tension roller nut and loosen the timing belt tension.
Turbocharged diesel engine: Remove the tensioner pulley.
Caution: The tension roller must be replaced every time the timing belt is replaced.
Turbocharged diesel engine: attach a new tension roller with an eccentric and tighten it firmly by hand. The tension roller must be in the released position.
If there is a semi-automatic tension roller: remove the guide roller "9", see figure No.130028 on the previous page.
Mark the direction of movement of the toothed belt with an arrow using chalk so that when installing the belt later (if the same belt is installed) keep this direction. Remove the toothed belt.
Note: When the camshaft is turned with the timing belt removed, no piston should be in the TDC position. Otherwise, serious damage to the pistons or valves may occur. If the camshaft needs to be turned, all pistons must first be moved approximately the same distance from the TDC position. To do this, mark the top of the crankshaft pulley with chalk (the crankshaft must be in a position where the piston of cylinder 1 is at TDC). After this, turn the crankshaft pulley 1/4 turn (90°) to the right or left. The mark on the pulley should be facing to the right or left, respectively.
Installation
Through the hole in the gearbox, check whether the TDC mark on the flywheel matches the installation mark.
Loosen the camshaft gear mounting bolt by approximately 1/2 turn. Displace the camshaft gear from the camshaft cone using hammer blows with a rod through the 6 mm hole in the rear timing belt guard.
Install the timing belt. If a previously used timing belt is reinstalled, the arrow marked on the timing belt must point in the same direction.
Engines up to 9/93 (without semi-automatic tension roller) tighten the toothed belt, see above.
If there is a semi-automatic tension roller: install the guide roller, tighten it to a torque of 25 Nm.
Engines from 10/93 with semi-automatic tensioner roller: turn the tensioner roller with a suitable key (for example, Matra V159) to the right until the spline and the projection are opposite each other (arrow). Now the tension of the toothed belt is maintained constant by the tension roller.
Tighten the tension roller mounting nut to 20 Nm.
Make sure that the crankshaft is in the TDC position for cylinder 1 using the mark on the flywheel, then tighten the camshaft gear mounting bolt to a torque of 45 Nm.
75 hp engine with 10/94 (AAZ): Tighten the 3 fuel injection pump gear mounting bolts to 25 Nm.
Remove the camshaft adjusting ruler and the injection pump gear locking pin.
Engines up to 9/93: Check the timing belt tension again to ensure it matches the specified value, tighten the belt if necessary.
75 hp engine with 10/94 (AAZ): Turn the crankshaft in the direction of rotation by 2 turns and set it again to the TDC position for cylinder 1. Secure the fuel injection pump gear with the locking pin. If this is not possible, loosen the mounting bolts and turn the hub of the fuel injection pump gear to a position in which the pin can secure it. In this position, tighten the fuel injection pump gear mounting bolts to a torque of 25 Nm.
Install the lower toothed belt cover and V-belt pulley. Apply and tighten the V-belt. Replace the cylinder head cover gasket, screw on cylinder head cover 1. Tighten the bolts to 10 Nm. Install the upper toothed belt cover.
Engines other than 75hp engine since 10/94 (AAZ): check injection pump start, see below.
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