Pic. 16. Camshaft drive of the VR6 engine
Pic. 91. Elements of the timing mechanism drive: 1 - intermediate shaft; 2 - drive ring; 3 - bolt, 10 Nm; 4 - sensor drive; 5 - bolt, 10 Nm; 6 - bolt, 25 Nm; 7 - elastic element of the tension device; 8 - tensioner of a double-row chain, 20 Nm; 9 - double row chain; 10 - double-row chain drive sprocket; 11 - single-row chain drive sprocket; 12 - chain tensioner with shoe; 13 - chain drive sprocket built into the crankshaft; 14 - single-row chain; 15 - damper bar; 16 - special bolt, 25 Nm; 17 - pin with shoulder, 25 Nm; 18 - calmer; 19 - bolt, 20 Nm; 20 - crankshaft sprockets
Before dismantling the main parts of the timing mechanism drive (pic. 91) it is necessary to remove all devices and components located on the front of the engine so that only the elements of the drive mechanism of the gas distribution mechanism remain unremoved (pic. 16).
Before removing the drive elements of the gas distribution mechanism, put the piston of the first cylinder in the TDC position, and after removing the two chains of the gas distribution mechanism drive, in no case should the crankshaft be rotated with the cylinder head removed, as this can lead to pistons hitting the valves.
Pic. 92. Marking places for camshaft drive chains (shown by arrows)
Before removing the chains, mark them with a color in places (pic. 92) in order to remember the direction of movement of the chains.
To reduce the tension of a two-row chain 9 (pic. 91) loosen the timing mechanism and remove the chain tensioner 8.
Pic. 93. Hexagons for fixing camshafts in a fixed position (shown by arrows)
To dismantle the double row chain, you must first remove the sprocket 20 (pic. 91), located on one of the camshafts, or remove the sprocket 10 from the intermediate shaft. In both cases, unscrew the sprocket mounting bolt 5. When loosening and tightening the mounting bolts of both sprockets, the camshafts must be fixed in a fixed position. To do this, hold the camshaft with an open end wrench «by 24 mm», put on one of the hexagons (pic. 93).
Loosen the fastening bolt 5 (pic. 91), remove the single row chain sprocket 11 together with the single row timing chain. Remove all other parts of the timing mechanism drive (pic. 91). When assembling, it is important to follow the recommended sequence of operations.
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