- the pressure in the engine lubrication system has dropped. The cause of this malfunction is often increased wear on the camshaft journals and the camshaft bearing housings in the cylinder head. When the sockets are worn out, the head of the block is replaced as an assembly, since the sockets are made directly in its body;
- valve knock, which is not eliminated by adjusting the clearances in the valve drive mechanism. It may occur due to increased wear of the camshaft cams due to the use of low-quality engine oil or damage to the oil filter.
Note. With severe wear of the camshaft cams, at the same time as replacing it, it is often necessary to replace the valve rockers.
Due to the layout of the engine compartment of the Renault Logan car, it is not possible to remove the camshaft directly on the car. To do this, the cylinder head must be removed.
You will need: the same tools as for removing the cylinder head (see «Replacing the cylinder head gasket») and replacement of valve stem seals, with the exception of those that are necessary directly for their replacement (tools are used only for preparatory operations) (see «Replacement of valve stem seals»), as well as additional keys «at 11», «at 16» (end head), «at 25», TORX T30, micrometer.
1. Remove the cylinder head (see «Replacing the cylinder head gasket»).
2. Evenly loosening the tightening, unscrew the five bolts securing the axis of the rocker arms...
Note. Please note that the bolts have different head shapes. Install the bolts when reassembling in their original places.
3.... and remove the axle assembly with rocker arms.
Note. If you do not intend to replace the rocker arms and their axle, do not remove the rocker arms from the axle in order to install them in their original places during assembly.
4. Holding the camshaft from turning with a hexagon wrench...
Note. The hexagon for holding is cast at the front journal of the camshaft bearing.
5.... Remove the bolt securing the camshaft pulley...
6.... and remove the pulley.
7. Prying with a screwdriver...
8.... remove the camshaft oil seal from the socket in the block head.
Note. Replace the camshaft oil seal with a new one each time it is removed.
9. At the rear end of the block head, unscrew the two screws securing the camshaft thrust flange...
10.... and remove the flange.
11. Carefully, trying not to damage the working surfaces of the bearings with the sharp edges of the cams, remove the camshaft from the beds of the block head.
12. Examine a camshaft. The surfaces of bearing journals 2 and cams 1 must be well polished and without damage, and in the groove a under the thrust flange there must be no signs of excessive wear and nicks. On the working surfaces of the necks 2, scoring, nicks, scratches, aluminum enveloping from the bearing seats in the block head are not allowed. If on the working surfaces of the cams 1 there are signs of seizing, overheating, deep scratches or wear in the form of a cut, as well as uniform wear of more than 0.5 mm, replace the shaft. Thoroughly clean deposits from channel b for supplying oil in the middle support journal.
Attention! Grinding of the camshaft cams to eliminate stepped wear is prohibited, since changing the size of the cam profile will disrupt the valve timing.
13. In workshops equipped with special tools and fixtures, you can check the radial runout of the camshaft journals. If its value is more than 0.02 mm or misalignment of the necks, replace the shaft, since its editing is not allowed.
Attention! When installing a new camshaft, we recommend replacing the rocker arms with new ones. Before starting the engine for the first time and to improve the running-in conditions, we recommend adding an anti-seize antifriction additive to the engine oil.
14. After installing the camshaft, check its axial clearance. If it is more than 0.15 mm, replace the thrust flange.
15. Establish a camshaft in a head of the block and all removed details in an order, the return to removal.
16. Install the cylinder head on the engine (see «Replacing the cylinder head gasket»).