Note: Cylinder heads with cracks between the valve seats or between the valve seat ring and the thread of the spark plug seat can be used without loss of service life if the cracks are small with a maximum width of 0.3 mm or if only the first 4 turns are involved. spark plug threads.
Note: Do not replace cylinder head and camshaft frame separately.
Note: After installing the camshafts, the engine must not be started for approximately 30 minutes. Hydraulic lifters must be deposited (otherwise the valves will come into contact with the pistons).
Note: After working on the valve train, rotate the engine by hand for at least two revolutions to ensure that no valve is in contact with the piston.
Note: Gaskets and O-rings must be replaced.
Pic. 2.109. Valve mechanism: 1 – bolt 50 Nm + tighten by 180° (1/2 rev.); 2 - camshaft sprocket; 3 - stuffing box; 4 – a head of the block of cylinders; 5 - valve guide sleeve; 6 - oil scraper cap; 7 - valve spring; 8 - valve spring plate, top; 9 - conical cracker; 10 - hydraulic compensator; 11 - parallel key; 12 - exhaust camshaft; 13 - camshaft frame; 14 - bolt 8 Nm + tighten 1/4 (90°); 15 - phase shifter; 16 - bolt 20 Nm + tighten 1/8 (45°); 17 - intake camshaft; 18 - chain tensioner; 19 - drive chain; 20 - bolt 10 Nm; 21 - bolt 10 Nm; 22 - Hall sensor; 23 - exhaust valve; 24 - inlet valve; 25 - plug
Details of the valve mechanism are shown in Figure 2.109.
Valve sizes
Pic. 2.110. Valve dimensions
Valve sizes are shown in the table below and in fig. 2.110.
It is forbidden to process intake and exhaust valves. Only lapping is allowed.
Valve sizes
Checking the valve guides
Insert the new valve into the guide sleeve. The end of the valve stem must be covered by the guide bushing. Due to the different stem diameter, use the inlet valve in the inlet valve guide only and the exhaust valve in the exhaust valve guide.
Pic. 2.111. Determining valve guide backlash
Determine valve play (pic. 2.111). Limit tolerance 0.8 mm.
If the swing play is exceeded
Replace cylinder head.
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