Removal
1. Remove the timing belt (see Chapter 7), but before releasing its tension, turn the crankshaft back approximately 60° (4 teeth). This will distribute the valve spring pressure evenly along the length of the camshaft, thereby preventing the risk of damage to the shaft bearing caps during its removal/installation (see illustration).
2. Remove the camshaft sprockets as described in Chapter 8.
3. On the intake camshaft, moving in a spiral from the outer part to the inner part, loosen the bearing cap bolts of the shaft by half a turn in one step to gradually reduce the pressure of the valve springs on the bearing caps.
Unscrew the bolts completely and remove them together with the caps. The bearing caps are numbered so that later they can be installed each in the same place (see illustration). Be careful not to lose the mounting pins.
Caution! If the bearing cap mounting bolts were loosened carelessly, the caps could break. If damage is found on at least one of the caps, replace the complete cylinder head assembly - the caps are not sold separately.
4. Remove the camshaft from the cylinder head and pull out the oil seal.
5. Repeat steps 3 and 4 and remove the exhaust camshaft.
6. Prepare sixteen small clean plastic containers (by number of valves) and number them; alternatively, divide the larger container into eight compartments. Remove the valve lifters one at a time, placing them in the corresponding numbered container (see illustrations). Do not mix up components from different cylinders, this will lead to accelerated wear.
Caution: Store hydraulic tappets upside down or oil will leak out.
Inspection
7. Inspect the camshaft and camshaft bearing surfaces for scratches and worn areas. Replace the camshaft if such damage is found. If the cylinder head surfaces are excessively worn, replace the head.
8. Inspect the tappet contact surfaces for wear and scratches. Check the tappet walls and tappet bores in the cylinder head for damage or signs of wear. If a tappet is suspected of being faulty or is visibly worn, it should be replaced.
Installation
9. Where removed, lubricate the tappets with clean engine oil and carefully insert each one into its original place in the cylinder head.
10. Place the camshafts in their operating position. Make sure the crankshaft is still approximately 60° BTDC and position the camshafts so that the cams of cylinder #1 point upward. Temporarily install the sprockets on the camshafts and make sure their timing marks are approximately 4 teeth before TDC.
11. Make sure that the mating surfaces of the bearing caps and cylinder head are clean and dry and lubricate the camshaft lobes and bearing journals with clean engine oil.
12. Apply a small amount of sealant (Opel recommends using composition 15 03170) on the areas of the cylinder head around the openings for the seals of the front camshaft bearing caps (see illustration).
13. Place the mounting pins (where are there) into working position, then install the bearing caps and their mounting bolts, each component strictly in its original place. The caps are numbered from the front to the rear of the engine, the same numbers are on the cylinder head.
14. On the intake camshaft, tighten the bearing cap bolts by hand, then, moving in a spiral from the center outward, tighten the bolts one-half turn at a time to gradually compress the valve springs (see illustration). Repeat this procedure until all bearing caps are seated on the cylinder head, then tighten the bolts to the specified torque Specifications.
Caution! If the bearing cap mounting bolts are tightened carelessly, the bearing caps may break. In this case, the complete cylinder head assembly will have to be replaced - bearing caps are not sold separately.
15. Tighten the exhaust camshaft bearing cap bolts as described in step 14.
16. Install new camshaft seals as described in Chapter 9.
17. Install the camshaft sprockets as described in Chapter 8.
18. Align all timing marks on the sprockets to position the camshafts and crankshaft at TDC, then install the timing belt (see Chapter 7).
19. Install the camshaft cover and timing belt cover as described in Chapter 4 and Chapter 6.
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