- the pressure in the engine lubrication system has dropped. The cause of this malfunction is often increased wear of the camshaft journals and camshaft bearing seats in the cylinder head. If the seats are worn out, the cylinder head is replaced as an assembly, since the seats are made directly in its body;
- valve knocking that cannot be eliminated by adjusting the clearances in the valve drive mechanism. May occur due to increased wear of the camshaft cams due to the use of low-quality motor oil or damage to the oil filter.
Note: If the camshaft cams are heavily worn, replacing the camshaft often requires replacing the valve rocker arms as well.
To replace the camshaft of K7J and K7M engines, do the following.
Note. Due to the specific layout of the engine compartment of the Renault/Dacia Sandero with the K7J or K7M engine, it is not possible to remove the camshaft directly on the vehicle. To do this, you need to remove the cylinder head.
You will need: the same tools as for removing the cylinder head (see "Replacing the cylinder head gasket") and replacement of oil scraper caps (see "Replacing valve stem seals"), except for those that are directly necessary for their replacement (tools are used only for preparatory operations), and also keys "11", "16" (socket head), "at 25", TORX T30, micrometer.
1. Remove the cylinder head (see "Replacing the cylinder head gasket").
2. Evenly loosen the tightening and unscrew the five bolts securing the valve rocker arm shaft...
Note: Please note that the bolts differ in the shape of their heads. Install the bolts in the same places when reassembling.
3. ...and remove the axle assembly with the rocker arms.
4. Hold the camshaft from turning with a hex key...
Note.
- The retaining hexagon is cast into the front journal of the camshaft bearing.
5. ...unscrew the camshaft toothed pulley mounting bolt...
6. ... and remove the screen.
7. Using a screwdriver, pry...
8. ... remove the camshaft oil seal from its socket in the cylinder head.
Helpful advice.
- Replace the camshaft seal with a new one each time it is removed.
9. At the rear end of the cylinder 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 cylinder head beds.
12. Inspect the camshaft. The surfaces of the bearing journals 3 (Fig. 5.12) and cams 1 must be well polished and without damage, and groove 4 for the thrust flange must not show signs of excessive wear or nicks. The working surfaces of journals 3 must not have any scoring, nicks, scratches, or aluminum drag from the bearing seats in the cylinder head. If the working surfaces of cams 1 show signs of seizure, overheating, deep scratches, or faceted wear, as well as uniform wear over 0.5 mm, replace the shaft. Carefully clean channel 2 for supplying oil in the middle bearing journal from deposits.
Warning: Grinding the camshaft lobes to eliminate step wear is prohibited, since changing the cam profile dimensions will disrupt the valve timing.
13. In workshops equipped with special tools and devices, you can check the radial runout of the camshaft journals. If its value is more than 0.02 mm or the journals are not aligned, replace the shaft, since its straightening is not allowed.
Fig. 5.12. Camshaft: 1 - cam; 2 - oil supply channel; 3 - support neck; 4 - groove for thrust flange
Warning: When installing a new camshaft, we recommend replacing the valve 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 anti-friction 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. Install the camshaft into the cylinder head and all removed parts in the reverse order of removal.
16. Install the cylinder head onto the engine (see "Replacing the cylinder head gasket").
To replace the camshafts of the K4M engine, do the following.
You will need: keys "8", "10", "13", "16", socket heads "10", "16", "18", TORX keys T8, TORXT14, bronze drift, engine support.
1. Disconnect the wire from the negative terminal of the battery (see "Removal and installation the battery").
2. Remove the engine crankcase guard (see "Removal and installation mudguards and engine crankcase protection").
3. Remove the accessory drive belt (see "Replacement of auxiliary drive belts").
4. Install a support under the engine.
5. Remove the ignition coils (see "Checking, removing and installing ignition coils of the K4M engine").
6. Disconnect the throttle cable and move it to the side (see "Replacing the throttle cable").
7. Remove the receiver (see "Replacing the cylinder head gasket").
8. Remove the cylinder head cover (see "Replacing the cylinder head cover gasket").
9. Remove the timing belt (see "Replacement and adjustment of belt tension, replacement of the timing drive tension roller").
10. Remove the intake camshafts...
11. ...and exhaust valves.
Note.
- The camshafts can be removed as a complete assembly with the gears.
- To do this, unscrew the nuts securing the toothed pulleys of the camshafts...
- ...and remove the toothed pulleys of the exhaust and intake camshafts.
12. Inspect the camshaft. Bearing journal surfaces 3 (see fig. 5.12) and cams 1 must be well polished and without damage, and groove 4 for the thrust flange must not have any traces of excessive wear or nicks. No scoring, nicks, scratches, or aluminum drag from the bearing seats in the cylinder head are allowed on the working surfaces of journals 3. If traces of seizure, overheating, deep scratches, or faceted wear, as well as uniform wear over 0.5 mm are found on the working surfaces of cams 1, replace the shaft. Carefully clean channel 2 for supplying oil in the middle support journal from deposits.
Warning: Grinding the camshaft lobes to eliminate step wear is prohibited, since changing the cam profile dimensions will disrupt the valve timing.
13. In workshops equipped with special tools and devices, you can check the radial runout of the camshaft journals. If the runout is more than 0.02 mm, replace the shaft, since its straightening is not allowed.
Warning: When installing a new camshaft, we recommend replacing the valve 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 anti-friction additive to the engine oil.
14. Install the camshafts into the cylinder head and all removed parts in the reverse order of removal.