Removal
1. Remove the cylinder head covers (see paragraph 4), toothed belt and camshaft sprockets (paragraph 6). If you plan to remove the front camshafts, then on 1997 and earlier models, also remove the ignition distributor (see chapter 5). To work with the rear block shafts, remove the intake manifold (see paragraph 8).
2. When removing the camshafts, care must be taken. The support cap bolts must be loosened strictly in the specified sequence. Otherwise, the pressure of the riveted springs will be unbalanced along the length of the shaft and the shaft may become warped and damage the supports. In this case, the cylinder head will have to be replaced. To equalize the spring pressure on the cams, rotate the shafts as shown in the figure 7.2,a,b.
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3. Gradually loosen the outer cover mounting bolts one by one, no more than 1/4 turn at a time in sequence. indicated in the figure 7.3.
4. Remove the seal and cover plug from the front end of the driven shaft.
5. Loosen the cover bolts in the sequence shown in the figure 7.5.a,b, 1/4 turn at a time, until it becomes possible to turn them out by hand.
6. Remove the covers and carefully pull the shafts out of the supports. Keep the shafts horizontal.
7. Repeat this operation on the remaining block.
8. Store lids in the order they were installed. The front block covers have letter markings, and the rear block covers have digital markings (figure 7.8,a). If necessary, remove the pushers using a magnet (with gaskets on engines produced since 1999) (figure 7.8,b). Also store the tappets with gaskets in the order they were installed so that when reassembling they will take their original place. Hydraulic tappets (models produced before 1997) store upside down in an oil bath.
Inspection
9. Inspect the camshafts, lifters and associated components as specified in chapter 2B. Technical data for camshafts and tappets are also given in chapter 2B.
Installation
10. Lubricate the tappets with molybdenum-based grease and insert them into the bores in their original locations. If there were adjusting shims on the tappets, insert them back into their original positions as well.
11. Lubricate the camshaft cams and journals, as well as the thrust surfaces of their gears, with molybdenum grease.
12. Place the camshafts in the supports and engage their gears so that the timing marks on the inner sides of the gears align (figure 7.12).
13. Apply a thin layer of RTV sealant to the outer edges of the cylinder head surfaces under the outer (thrust) camshaft bearing caps. Be careful not to let the sealant get on the shaft journals.
14. Check the shaft rotation (see Fig. 7.2, a, b). Install the thrust flanges onto the caps behind the shaft gears. Tighten the bolts only until the cover is seated in place.
15. Install the remaining covers back in place.
Note: The front block shaft covers are marked with letters, while the rear block shaft covers are marked with numbers.
16. Tighten the cover bolts in five or six passes (1/4 turn at a time) until the required force is achieved. Tighten the bolts in the recommended sequence (figure 7.16, a, b).
17. Wet the working edge of the shaft seal with clean engine oil. Insert the cuff into the socket and press it through a mandrel slightly smaller than the outer diameter of the cuff (figure 7.17). After pressing, the cuff should protrude from the socket by approximately 5 mm.
18. Insert plugs into the ends of the outer supports of the driven shafts. Before installing the plugs, apply RTV sealant to them. Press the plugs flush with the supports using a mallet.
19. Install the remaining parts in the reverse order of removal.
20. On models produced since 1998, check and, if necessary, adjust the valve clearances.
21. Start the engine and check its operation.