Attention! Before performing work, prepare two bolts with a thread of 6x1 mm and a length of 16–20 mm, which will be used as auxiliary during disassembly (see below).
Removing
1. Remove the cylinder head cover (see subsection 3.2.3).
2. Set the piston of the 1st cylinder to the TDC of the compression stroke. Make sure the dot marks (1) on the drive and driven gears of the camshafts are aligned and located on the same line parallel to the split plane of the cylinder head and cover, and the marks (2) turned in different directions. Otherwise, check that the TDC risk of the crankshaft is aligned with the zero division of the scale and turn the crankshaft 1 revolution.
3. Measure the end play of each camshaft. If the play exceeds the maximum allowable, then the camshaft and (or) the cylinder head must be replaced.
4. Remove the ignition distributor (see subsection 3.4.6).
5. Remove tensioner cover bolts (indicated by arrows).
6. Remove the tensioner from the front cover.
7. Label the chain link opposite the dot mark (indicated by arrows).
8. Unscrew the sprocket bolt while holding the camshaft with a wrench on the special flats.
9. Remove the distributor drive gear. Carefully remove the star (arrow) and chain from the camshaft and leave them on the guides.
Exhaust camshaft
1. First, remove the exhaust camshaft after fixing the auxiliary gear spring.
Attention! Remove the camshafts one by one, keeping them parallel to the plane of the cylinder head. Otherwise, damage to the lug on the cylinder head, which provides the standard axial play of the camshaft, is possible.
2. To fix the spring, turn the camshaft so that the service hole for the auxiliary bolt is facing vertically upwards. Attach the auxiliary gear to the main gear with a pre-prepared bolt with an M6 thread and a length of 16-20 mm.
3. Turn the intake camshaft so that the marks (1) gears shifted at an angle of 35°relative to the horizontal axis.
4. Move the camshaft back, gradually and evenly unscrew the bolts of the cover of the necks of the camshaft N1 (the sequence of removing the covers of the camshaft bearing journals is indicated by numbers).
5. Carefully unscrew the bolts of covers 2, 3, 5 and 7, evenly loosening the left and right bolts. Do not loosen cover bolts 4 and 6.
6. Carefully unscrew the bolts of covers 4 and 6, making sure that the camshaft rises evenly relative to the plane of the cylinder head. If the camshaft comes out skewed, tighten the bolts of covers 4 and 6, install covers 1, 2, 3, 5 and 7 and repeat the procedure. Achieve a parallel release of the camshaft.
Intake camshaft
1. Turn the intake camshaft so that the marks (1) gears shifted at an angle of 25°relative to the horizontal axis.
2. Move the camshaft forward, gradually and evenly unscrew the cover bolts N1.
3. Carefully unscrew the bolts of covers 3, 4, 6 and 7, evenly loosening the left and right bolts. Do not loosen cover bolts 2 and 5.
4. Carefully unscrew the bolts of covers 2 and 5, making sure that the camshaft rises evenly relative to the plane of the cylinder head. If the camshaft comes out skewed, tighten the bolts of covers 4 and 6, install covers 1, 3, 4, 6 and 7 and repeat the procedure. Achieve a parallel release of the camshaft. Remove the intake camshaft.
5. Wipe the adjusting washers of the pushers from the oil, mark with a marker and remove the pushers and adjusting washers.
6. Store bearing caps, pushrods and washers in the order in which these parts were installed.
7. Clamp the intake camshaft in a vise on the hex neck. Using a wrench with two thrust pins, turn the secondary gear clockwise, then unscrew the auxiliary bolt securing the main and auxiliary gears, and carefully loosen the force, allowing the auxiliary gear to turn counterclockwise until the spring is completely released.
8. Remove the sub gear circlip.
9. Remove spring washer (1), auxiliary gear (2) and auxiliary gear spring (3).
Examination
Installing the camshaft bearing caps
The camshaft journal covers are marked with numbers and orientation arrows, which must point towards the front of the engine.
Determining the clearance in the camshaft bearing journals
The clearance in the bearing journals of the camshafts is determined by the width of the crushed plastic gauge wire.
1. Measure the distance between the ends of the auxiliary gear spring in the free state and compare with the standard. If the distance differs from the standard, then replace the spring.
2. Check up a condition of pushers. The presence of chips and deep development is not allowed.
3. Check for signs of wear on the bearing journals and camshaft cams - grooves, pits, metal enveloping and signs of overheating (bluish colored areas). Check each cam for delamination of the hardened layer. Measure the size of each camshaft cam and compare with the standard. If the size of at least one of the cams is smaller than the standard, then replace the camshaft with a marker and remove the pushers and shims.
4. Measure the diameter of the camshaft bearing journals and compare with the standard. If the diameter of at least one bearing neck is less than the standard, then replace the camshaft.
5. Check the bearing journal clearances for each camshaft by proceeding as follows:
- clean the camshaft bearing journals and bearing journal covers in solvent;
- carefully place the camshaft (s) into the cylinder head without pushers, shims and auxiliary gear. The presence of oil on the necks is not allowed;
- lay pieces of plastic gauge wire across each camshaft bearing journal;
- Install the camshaft bearing caps with the arrows pointing towards the front of the engine (see fig. Installing the camshaft bearing caps);
- tighten the bolts to the specified torque by turning each bolt 1/4 turn at a time;
Attention! Turning the camshaft with the plastic gauge inserted is not permitted.
- unscrew the bolts and remove the covers;
- compare the width of the crushed wire (at the widest point) with a scale on the packaging (see fig. Determining the clearance in the camshaft bearing journals);
- if the clearance in at least one of the necks exceeds the norm, then the camshaft and (or) the cylinder head must be replaced;
- Use your fingernail or credit card to scrape off the remaining plastic, being careful not to scratch the support neck or the inside of the lid.
6. With the bearing journal covers temporarily installed, check the clearance in the meshing of the camshaft gears. Holding one of the camshafts by the hex neck with a wrench, check the amount of movement of the gear of the other camshaft. Compare the result with the standard. If the clearance is higher than normal, replace both camshafts.
Installation
Intake camshaft
1. Lubricate and install the pushers and shims in their original places, having previously lubricated with molybdenum grease.
2. Lubricate the bearing journals and camshaft cams with molybdenum grease. Lubricate the thrust portion of the intake camshaft.
3. Install the intake camshaft into the cylinder head with lobes 1 and 4 facing down.
4. Move the camshaft forward and install the journal covers 2 and 5, observing the numbering and orientation of the arrows, which must be directed towards the front of the engine.
5. Slightly tighten bearing journal covers 2 and 5.
6. Install covers 3, 4, 6, 7 and, observing the sequence, slightly tighten the bolts of the covers until they come into contact with the cylinder head.
7. Install cover 1 and tighten both bolts evenly.
8. Tighten all cap bolts to the specified torque in several stages.
Exhaust camshaft
1. Assemble exhaust camshaft with springs and auxiliary gear, secure all parts with circlip.
2. Install the pushers and shims in their original places, pre-lubricated with molybdenum grease.
3. Lubricate the bearing journals and camshaft cams with molybdenum grease.
4. Align the marks on the camshaft gears (1 - combination). These marks must be 180°apart from their position when the camshafts are removed.
5. It should be borne in mind that the design of the gas distribution of the engine in question does not allow interference connections. The cap bolts should be tightened in this position, after which the camshaft should be rotated back to set to the TDC position, in which the contact surfaces are in contact evenly, without obstacles from the forces of the springs acting on the cams.
6. Rotate the exhaust camshaft over the intake camshaft and reinstall. Rotate the camshaft in both directions to ensure proper seating in the journals.
7. Install covers 4 and 6, observing the numbering and orientation of the arrows, which must be directed towards the chain.
8. Slightly tighten covers 4 and 6.
9. Install covers 2, 3, 5, 7 and, observing the sequence, slightly tighten the bolts of the covers.
10. Install cover 1 and tighten both bolts evenly.
11. Tighten all cap bolts to the specified torque in several steps.
12. Turn the camshafts so that the auxiliary bolt is at the top and remove the bolt. Check for smooth rotation of the camshafts.
13. Align the camshafts so that the position of the marks corresponds to TDC. Make sure the notch on the crankshaft pulley is aligned with the TDC mark on the scale.
14. Install the chain with an asterisk, checking the coincidence of the marks made during disassembly. Tighten the bolt.
15. Install the chain tensioner, replacing the gasket. Press on the tensioner, wrap and tighten the nuts.
16. Install the rest of the parts in reverse order. Adjust valve clearances (see subsection 2.29).