Removal
1. Remove the cylinder head and timing chain covers (paragraph 5, 9).
2. Temporarily screw the bolt into the end of the crankshaft so that the shaft can be turned.
3. Remove the MGR chains (paragraph 10).
4. If you are removing the intake camshaft of the front cylinder head, pull the tensioner of the coolant pump drive belt toward the camshaft and remove the belt. Unscrew the bolts securing the oil seal housing to the left end of the front cylinder head. You do not have to remove the coolant pump pulley. However, you can remove the pulley and then unscrew the oil seal housing bolts (see Fig. 12.4, a-g).
5. Check the marks on the camshaft bearing caps. The bearing cap designation includes the bearing number and the letter "R" (right) or "L" (left) corresponding to the cylinder head. The rear cylinder head is right, and the front is left (see Fig. 12.5, a, b).
6. Servicing the cylinder heads one by one, first remove the caps that take up the axial force - 1L and 5L or 1R and 5R. These caps can be removed before you loosen the other bolts. Unscrew the bolts and remove these caps (see Fig. 12.6).
7. Sequentially loosen (see Fig. 12.7, a-c) the bolts of the remaining covers. Remove the covers, if necessary, by tapping them with a soft-faced hammer.
8. Remove the camshafts and store them so as not to mix them up during installation (see Fig. 12.8, a-g).
9. Note the position of the rocker arms. Remove them and store them so as not to mix them up during installation (see Fig. 12.9).
10. Remove the hydraulic lifters and place them in a box with numbered sections (see Fig. 12.10).
Inspection
11. After removing the camshafts and hydraulic lifters, inspect them for wear (scratches, wear spots, etc.) and ovality. Replace faulty components if necessary.
12. Measure the outside diameter of each hydraulic lifter. Measure the diameter at the top and bottom of the hydraulic lifter, and then repeat the measurements in a perpendicular direction. If any of the obtained dimensions differ significantly from the others, then the lifter is taper or out of round and must be replaced. If you have the necessary equipment, measure the inside diameter of the corresponding hole in the cylinder head. Compare the obtained dimensions with the technical requirements. If the hydraulic lifters or the holes for them are excessively worn, then you will need new hydraulic lifters and / or a new cylinder head.
13. If the valve mechanism is knocking, especially when starting a cold engine, then the cause is probably a faulty hydraulic compensator. Only an experienced auto mechanic who knows such engines can determine by ear whether such noise is normal or whether one or more hydraulic compensators need to be replaced.
14. Inspect the camshaft lobes for scuffs, wear spots, areas of metal wear or galling, and overheating (temper color) zones. Inspect the hardened surface layer of each cam for chipping. If such signs are found, replace the camshaft.
15. Inspect the camshaft bearing journals and cylinder head bearing surfaces for wear, particularly pitting. If any such signs are found, replace the cylinder head.
16. Using a micrometer, measure the journal diameters in several places. If the diameter of one journal is less than the specification, replace the camshaft. If you have a micrometer to check the internal dimensions, measure the bores formed by the cylinder head and bearing caps.
17. Measure the axial clearance of the camshaft with a dial indicator. To do this, install it on the cylinder head so that the tip of the indicator rests on the end of the camshaft. Press the camshaft against the indicator, zero the indicator, then press the camshaft away from the indicator and read the readings. If the result obtained corresponds to the maximum clearance or exceeds it (see Technical Requirements), then the covers that absorb the axial force must be replaced.
Installation
18. When servicing the front cylinder head, generously lubricate the hydraulic compensators and the holes for them in the cylinder head with oil. If new hydraulic compensators are installed, they must first be filled with oil. Carefully install the hydraulic compensators in the cylinder head - in their places, with the appropriate side. Insert the hydraulic compensators into the holes without distortions.
19. Lubricate the rocker arms and install them in their places.
20. Generously lubricate the camshaft bearing journals with oil. Install the camshafts in their places. The mark on the intake camshaft sprocket should be at the 9 o'clock position. The mark on the exhaust camshaft sprocket should be at the 12 o'clock position (see Fig. 12.20, a, b).
21. Install the camshaft bearing caps in their places. Insert the bolts and tighten them by hand in sequence. Then tighten the bolts to the required torque (see Fig. 12.21,a,b).
22. Install the front head chain (paragraph 10).
23. When servicing the rear cylinder head, generously lubricate the hydraulic compensators and the holes for them in the cylinder head with oil. If new hydraulic compensators are installed, they must first be filled with oil. Carefully install the hydraulic compensators in the cylinder head - in their places, with the appropriate side. Insert the hydraulic compensators into the holes without distortions.
24. Lubricate the rocker arms and install them in their places.
25. Generously lubricate the camshaft bearing journals with oil. Install the camshafts in their places. The mark on the intake camshaft sprocket should be at the 3 o'clock position. The mark on the exhaust camshaft sprocket should be at the 12 o'clock position (see Fig. 12.25, a, b).
26. Install the camshaft bearing caps in their places. Insert the bolts and tighten them by hand in sequence. Then tighten the bolts to the required torque (see Fig. 12.26).
27. Install the rear head chain (paragraph 10).
28. Install the MGR and cylinder head covers (paragraph 5, 9).
29. If the front head intake camshaft seal housing has been removed, install it on a new gasket. Then press on the coolant pump pulley (see Fig. 12.29,a,b).
