The gap is measured with a feeler gauge on a cold (at a temperature of +20°C) or warmed up engine (at operating temperature) between the camshaft cams (the cam must be directed away from the pushrod) and the valve tappet adjusting washer.
For a cold engine, the nominal clearance on the intake camshaft is (0.25±0.04) mm, on the exhaust shaft – (0.31±0.04) mm.
You will need: a set of feeler gauges, 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 cylinder head).
3. Measure the clearances with a set of feeler gauges. If the clearances are not within the norm, use the feeler gauges to determine the actual clearance and record the values obtained. Measure the clearances in the remaining valves in the same way. 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;
- turn the crankshaft again by half a turn. In this position, check the clearance on the cams of the intake 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 valve clearances are not within the standard, adjust the clearances. It is necessary to replace the tappets of those valves whose clearances differ from the nominal values. To adjust the valve clearances, remove the camshafts (see Removal, inspection and installation of camshafts).
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4. Remove the valve lifters.
5. The adjustment size to which the pusher corresponds is marked on the inner side of the pusher.
6. Calculate the size (all values in mm) adjusting pusher N according to the formula
N = T + A – S, Where
T — size of the removed pusher;
A - measured valve clearance;
S — nominal clearance.
7. Install the valve lifters with the dimensions calculated by the formula and all the removed parts in the reverse order of removal, check the clearances. If necessary, repeat the operations indicated above.
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