Removal and installation the cylinder head
On a car, this is done if it is not necessary to remove the engine itself to fix the problem, or if it is only necessary to remove carbon deposits from the surface of the combustion chamber and valves. The sequence of operations is as follows.
Drain the coolant from the radiator and cylinder block, remove the air filter and close the carburetor neck with a technological plug. Disconnect the wires from the battery, spark plugs and from the coolant temperature gauge sensor, disconnect the air damper drive cable from the carburetor.
Key 67.7812.9514 (tubular end) remove the coolant temperature sensor. Disconnect the throttle actuator rods from the intermediate lever on the cylinder head cover and remove the cover.
Set the gear shift lever to neutral and turn the crankshaft until the mark on the camshaft sprocket aligns with the mark on the bearing housing (see fig. 56). This operation is necessary to ensure that the camshaft sprocket is correctly positioned when installing the cylinder head on the engine.
Disconnect the hoses from the carburetor, the intake pipe, the outlet pipe of the cylinder head cooling jacket and the pipe supplying liquid to the heater, and disconnect the bracket for fastening the pipe for draining liquid from the heater, the protective shield of the starter and the inlet pipe of the mufflers from the exhaust manifold.
It is better to leave the exhaust manifold and intake pipe with the carburetor on the head. It is more convenient to remove them later when disassembling the cylinder head.
Loosen the cap nut 5 (see fig. 46) chain tensioner, press the tensioner rod with a mounting blade and secure it with a cap nut. Remove the camshaft sprocket and lower the chain down, preventing it from slipping off the oil pump drive shaft sprocket.
Loosen the bolts securing the cylinder head to the block and remove the cylinder head and the gasket located between the head and the cylinder block.
Install the cylinder head on the block in the reverse order. Before installation, check that the centering bushings on the cylinder block are in place in the sockets for bolts 7 and 10 (fig. 13, a).
The cylinder head mounting bolts are tightened in a specific sequence (fig. 13, a) in two steps: first tighten bolts 1–10 to a torque of 3.4–4.2 kgf·m, then tighten them to a torque of 9.8–12.1 kgf·m, after which tighten bolt 11 to a torque of 3.2–4.0 kgf·m.
When installing the camshaft sprocket, it is necessary to pay attention to the alignment of the installation marks (see fig. 56 and 57) and tighten the chain as indicated in section 1.11 "Engine adjustments".
When installing the cylinder head cover with a gasket, the cover mounting nuts should be tightened to a torque of no more than 0.8 kgf·m, so as not to cause the gasket to break along the mounting holes and warp the cover. Each time the engine is disassembled, it is recommended to replace the cover gasket with a new one.
After installing the cylinder head, check and adjust the ignition timing, the gap between the levers and camshaft cams, as well as the air and throttle valve drive of the carburetor.
Disassembly and assembly of the cylinder head
If only one part needs to be replaced, then you don't have to disassemble the cylinder head completely and remove only the damaged parts. The cylinder head is disassembled completely in the following sequence.
Install the cylinder head on a wooden stand A.60335, unscrew the nuts and remove the carburetor with the gasket, intake pipe and exhaust manifold (the hot air intake is removed at the same time). Remove the outlet pipe of the cooling jacket and the pipe that drains the liquid to the heater.
Loosen the fastening nuts and remove the bearing housing with the camshaft and thrust flange.
Remove levers 4 (see fig. 12) valves with springs. Loosen locknuts 6 and unscrew adjusting bolts 5 and, if necessary, their bushings 12. Install device A.60311/R, as shown in fig. 12, b, compress the valve springs and release the crackers. Instead of the portable device A.60311/R, you can also use the stationary device 02.7823.9505. Remove the valve springs with plates and support washers. Turn the cylinder head and take out the valves from the bottom. Remove the oil-deflecting caps from the guide bushings.
Assemble the cylinder head in reverse order. Before assembly, lubricate the valves and new oil-deflecting caps with engine oil (old ones are not allowed to be used).
The camshaft with the bearing housing is installed in the following order. Insert the camshaft lubricated with engine oil into the bearing housing and secure it with a thrust flange. Put the sprocket on the camshaft (without securing it) and turn it until the alignment marks on the sprocket and bearing housing are aligned (see fig. 56). Remove the sprocket and, without disturbing the position of the camshaft, install the bearing housing on the cylinder head.
Check if the mounting bushings are inserted (around the studs and in Fig. 13, b) into the holes of the bearing housing, and then tighten the bearing housing fastening nuts in the sequence shown in Fig. 13, b.