Checking the timing belt tension (Opel Vectra B)

After all work on the toothed belt drive, its tension must be checked and, if necessary, adjusted. The check is carried out with a cold engine.

The valve timing has been checked and a new timing belt has been installed (the traction side is taut, otherwise correct adjustment is not possible).
8-valve engine: turn the crankshaft manually two revolutions in the direction of engine rotation and then set it again to the TDC ignition position. Are the valve timing phases correct?
When the timing belt tension is correct, the arrow on the moving part of the tension roller is opposite the mark on the support plate of the tension roller.
To adjust the tension of the toothed belt, slightly loosen the water pump mounting bolts and turn the eccentrically located pump with the KM-421-A tool clockwise. The movable part of the tension roller should now be at the right stop.
If you don't have a special tool, you can use a gas wrench to turn the water pump.
Tighten the bolts, turn the engine over twice and return it to TDC.
Rotate the water pump again until the arrow and mark on the tension roller align
Tighten the water pump bolts (8 Nm), crank the engine twice and check the timing belt tension again.
16V: First check the basic installation of the water pump. The protrusion on the pump must match the corresponding opposite part on the engine block. If necessary, turn the water pump accordingly. Tighten the water pump bolts to 25 Nm.
Turn the crankshaft manually twice in the direction of engine rotation and then set it to the TDC ignition position again. Are the valve timing correct?
The timing belt tension is correct if the pointer and the mark on the tension roller match.
To adjust, loosen the tension roller mounting bolt and tighten the adjusting eccentric counterclockwise until the arrow on the tension roller is at the right stop of the mark.
Tighten the tension roller mounting bolt in this position (20 Nm).
Manually turn the crankshaft twice in the direction of engine rotation and then return it to the TDC ignition position.
Loosen the tensioner roller mounting bolt again.
Turn the adjusting eccentric clockwise until the arrow and mark on the tension roller match, tighten the tension roller.
Turn the engine over twice and return it to TDC.
Check the timing belt tension again.

Setting the valve timing

The valve control and crank mechanism work in harmony only when the valve timing is set correctly. Incorrectly set valve timing results in poor engine power and, in extreme cases, can even cause severe engine damage if the piston base hits valves that are not closed in time.

The figures show checking and adjusting the timing belt tension in a 16-valve engine.

Left: Check the installation position of the water pump.

Right: Loosen the tension roller mounting bolt and tighten the adjusting eccentric counterclockwise until the arrow on the tension roller is at the right stop of the mark. Tighten the tension roller mounting bolt.

In a 16-valve 1.6L engine, the valve timing is set correctly if the mark on the crankshaft pulley is opposite the arrow on the engine block. At the same time, the marks (arrows in the photo on the left) on the front sides of the camshafts should be opposite each other and coincide with the upper edge of the cylinder head. In the 16-valve 1.8/2.0 L engine, the marks on the camshaft pulleys should be at the same height as the marks on the rear timing belt cover (photo on the right).

The toothed belt has been removed.
On an 8-valve engine, rotate the camshaft pulley so that the mark on the front side of the pulley is at the same height as the mark on the rear timing belt cover.
Make sure that no piston is in the TDC position when the camshaft rotates, otherwise the valves or piston bases may be damaged.
On a 16-valve 1.6L engine, rotate the camshaft pulleys so that the marks on the front sides of the pulleys are opposite each other and coincide with the top edge of the cylinder head.
In this case, too, not a single piston should be in the TDC position.
On 16-valve 1.8 and 2.0 L engines, rotate the camshaft pulleys so that the marks on the front sides of the pulleys are at the same height as the mark on the rear timing belt cover.
In this case, too, not a single piston should be in the TDC position.
For all engines: Using the timing belt drive pulley mounting bolt, turn the crankshaft until the dash mark on the timing belt drive pulley aligns with the center of the milling on the oil pump housing (8-valve engine) or with a mark on the rear cover of the timing belt (1 6V).
Install a new timing belt (the side of the tensile force is taut). Do not change the position of the camshaft and crankshaft anymore.
Check the timing belt tension.