The gap is measured with a feeler gauge when cold (at +20°C) or warm engine (at operating temperature) between the camshafts (the cam must point away from the pusher) and adjusting washer of the valve lifter.
For a cold engine, the nominal intake camshaft clearance is (0,25±0,04) mm, on the exhaust shaft - (0,31±0,04) mm.
You will need: a set of probes, a micrometer.
1. Remove the cylinder head cover (see Replacing the cylinder head cover gasket).
2. Set the piston of the 1st cylinder to the TDC position of the compression stroke (see Setting the piston of the first cylinder to the TDC position of the compression stroke). In this case, the cams of the intake valves of the 2nd cylinder and the exhaust valves of the 3rd cylinder should be directed upwards and located symmetrically at a slight angle inward (to the center of the block head).
3. Measure the gaps with a feeler gauge. If the gaps are out of specification, use feeler gauges to determine the actual gap and record the values. Similarly, measure the clearances in the remaining valves. To do this, do the following:
- turn the crankshaft half a turn. In this position, check the clearances on the cams of the intake valves of the 1st cylinder and the exhaust valves of the 4th cylinder;
- again turn the crankshaft half a turn. In this position, check the gap on the cams of the inlet valves of the 3rd cylinder and the exhaust valves of the 2nd cylinder;
- turn the crankshaft another half turn and check the clearance on the cams of the intake valves of the 4th cylinder and the exhaust valves of the 1st cylinder.
If the clearances in the valve drive are not correct, adjust the clearances. It is necessary to replace the tappets of those valves whose clearances differ from the nominal values. To adjust the clearances in the valve drive, remove the camshafts (see Removal, troubleshooting and installation of camshafts).
4. Remove the valve lifters.
5. On the inner side of the pusher there is an adjusting size to which the pusher corresponds.
6. Calculate the size (all values in mm) adjusting pusher N according to the formula
N = T + A – S, Where
T is the size of the removed pusher;
And — the measured backlash in the valve;
S is the nominal gap.
7. Install the valve lifters with the dimensions calculated by the formula and all removed parts in the reverse order of removal, check the clearances. Repeat the steps above if necessary.
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