Balance Mechanism — Removal and Installation (2.0L Engines Only) (Opel Astra G)

Removal

1. The mechanism consists of 2 balance shafts driven by the crankshaft (see photo).



2. Remove both sections of the pan, unscrew the bolts and remove the balance mechanism and gasket.

Installation

3. If the crankshaft, main bearing caps or balance mechanism were changed during disassembly, the clearance in the engagement of the mechanism gears should be checked and adjusted if necessary. If the replacement of the specified parts was not performed, the removed balance mechanism gasket should be installed.

4. The gap is checked using the OPEL KM949 device as follows.

• a. Set the piston of the 1st cylinder to TDC of the compression stroke.

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• b. Align both balance shafts so that the flats are in line at the bottom when viewed from the right side of the engine (see photo).

• c. Install the gasket and tighten the mechanism mounting bolts.
• g. Screw the long knurled bolt of the OPEL KM949 device into the balance shaft from the intake valve side, set the lever to 9 o'clock and tighten the bolt by hand.
• d. Screw the short knurled bolt into the other shaft and tighten it by hand.
• e. Install the pointer indicator (see photo), select the free play of the gear by turning the bolt screwed into the shaft from the exhaust valve side and set the indicator to zero. Turn this bolt in the opposite direction and determine the indicator reading.
• f. Turn the crankshaft so that the lever of the device is at 6 o'clock, release the bolt and set the lever again to 9 o'clock. Repeat the clearance measurements in this position of the shafts.
• z. Repeat the same measurements, turning the crankshaft further by 90° (the gap must be measured in 4 positions of the balance shafts).

5. If the gap differs from the norm, adjust it by selecting the thickness of the balance mechanism gasket. The gasket has thickness markings. Changing the gasket number to 1 corresponds to a change in the gear engagement gap by 0.02 mm. For example, if the measured gap is 0.08 mm, and the gasket has the marking "70", then installing a gasket marked "67" will decrease the gap by 0.06 mm. Install the required gasket and check the gap.

6. If this is not the case, the gap should be checked at a car service center.