Removing
1. Remove the toothed belt (see chapter 7), but before releasing it, rotate the crankshaft back approximately 60° (4 teeth). This will distribute the pressure of the valve springs evenly along the length of the camshaft, thereby preventing the risk of damage to the shaft bearing caps when removing/installing it (see illustration).
2. Remove the camshaft sprockets as described in Chapter 8.
3. On the intake camshaft, working in a spiral from the outside to the inside, loosen the shaft bearing cap bolts a half turn in one step to gradually relieve the valve spring pressure on the bearing caps.
Unscrew the bolts completely and remove them together with the covers. Bearing caps are numbered so that later they can be installed each in its original place (see illustration). Be careful not to lose the mounting pins.
Attention! If the bearing cap bolts were carelessly loosened, the caps could break. If damage is found on at least one of the covers, replace the complete cylinder head assembly - covers are not sold separately.
4. Take a cam-shaft from a head of the block of cylinders and pull out an epiploon.
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 by one, placing them in a container with the corresponding number (see illustrations). Do not mix up components from different cylinders, this will accelerate their wear.
Attention! Store hydraulic tappets without turning them upside down, otherwise oil will leak out of them.
Inspection
7. Inspect the running surfaces of the camshaft and cam bearings for scratches and gouges. Replace the camshaft if such damage is found. If the cylinder head running surfaces are excessively worn, replace the head.
8. Examine contact surfaces of pushers with cams on presence of the developed places and scratches. Check the walls of the tappets, as well as the holes under them in the cylinder head for damage and signs of wear. If the pusher is suspected to be defective or appears to be worn, it should be replaced.
Installation
9. Where removed, lubricate the tappets with clean engine oil and carefully insert each into its original place in the cylinder head.
10. Place camshafts in working position. Make sure the crankshaft is still at approximately 60°BTDC and position the camshafts so that the lobes of cylinder #1 are pointing up. Temporarily install the sprockets on the camshafts and make sure their timing marks are approximately 4 teeth before TDC.
11. Make sure that the contact surfaces of the bearing caps and cylinder head are clean and dry and lubricate the cams and camshaft bearing journals with clean engine oil.
12. Apply a small amount of sealant (Opel recommends compound 15 03170) on the areas of the cylinder head around the openings for the seals of the covers of the front bearings of the camshafts (see illustration).
13. Place the alignment pins (where there are) to the operating position, then install the bearing caps and their fastening bolts, each component strictly in its original place. The covers are numbered from front to rear of the engine, the same numbers are on the cylinder head.
14. On the inlet camshaft, hand-tighten the bearing cap bolts, then, spiraling outward from the center, tighten the bolts half a turn in one step 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.
Attention! If the bearing cap bolts are not 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 paragraph 14.
16. Install new camshaft seals as described in Chapter 9.
17. Install the camshaft sprockets as described in Chapter 8.
18. Align all alignment marks of the sprockets to bring the camshafts and crankshaft to the TDC position, then install the toothed belt (see chapter 7).
19. Install the camshaft cover and toothed belt cover as described in Chapter 4 and Chapter 6.
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