- the pressure in the engine lubrication system has dropped. The cause of this malfunction is often increased wear on the camshaft journals and camshaft bearing beds in the cylinder head. When the beds and their covers are worn out, the block head is replaced as an assembly, since the beds are made directly in its body;
- valve knock at normal clearances in the valve drive mechanism. It is caused by increased wear of the camshaft cams due to the use of low-quality engine oil or damage to the oil filter.
You will need: the same tools as for removing the timing belt (see «Replacing camshaft seals»), as well as a TORX E11 key, a torque wrench.
1. Remove the cylinder head cover (see «Replacing the cylinder head cover gasket»).
2. Remove the timing belt (see «Replacing the timing belt»).
3. Having fixed the camshafts from turning, unscrew the bolts securing the camshaft pulleys..
4.... and remove the pulleys from the shafts.
5. Turn out bolts of fastening of covers of bearings of camshafts in an order, the return shown on fig. 5.10…
6.... remove the covers, seals from the necks of the camshafts..
7.... and remove the camshafts.
Attention! The camshaft bearing caps are marked with serial numbers. Remember or write down the location of the covers in order to install them in their original places: the covers are processed together with the cylinder head and it is forbidden to depersonalize them.
Note. Replace the camshaft seals with new ones each time they are removed.
8. Inspect the camshafts. The surfaces of the bearing journals and cams must be well polished and without damage. On the working surfaces of the necks, scoring, nicks, scratches, aluminum enveloping from the bearing seats in the block head are not allowed. If there are signs of seizing, overheating, deep scratches or wear in the form of a cut on the working surfaces of the cams, replace the shafts.
Attention! Grinding of camshaft cams to eliminate stepped wear is prohibited, since when changing the size of the cam profile, the valve timing will be violated.
9. In workshops equipped with special tools and fixtures, you can check the radial runout of the camshaft journals. If the runout is greater than 0.02 mm or the journals are misaligned, replace the shaft as it cannot be straightened.
10. Lubricate the beds of the camshafts with clean engine oil and lay the camshafts in them in such a position that none of the cams rests on the shim of the valve lifter with the highest part of its toe.
11. Lubricate the front camshaft bearing caps with sealant.
Pic. 5.10. The order of tightening the bolts of the camshaft bearing caps
12. Establish covers of bearings of camshafts and tighten bolts of their fastening in the order shown in fig. 5.10, in three steps:
- 1st step - Tighten the bolts evenly by half a turn each until the bearing caps are in contact with the surfaces of the cylinder head;
- 2nd stage - tighten the bolts of the camshaft bearing caps to a torque of 7 Nm;
- 3rd stage - tighten the bolts of the camshaft bearing caps by 45°.
13. Press the camshaft oil seals into the sockets of the front camshaft bearing caps (see «Replacing camshaft seals»).
14. Install the remaining parts in the reverse order of removal.
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