Valve clearances on all engines are adjusted when warm, but the engine must not be running. To set the engine after repair the necessary working valve clearances, in Specifications values are given for the cold state. However, the clearances of all valves will need to be checked after the engine has cooled down. If it is necessary to adjust the valve clearances, preparatory work must be carried out, i.e. the cylinder head cover is removed, the spark plugs are unscrewed, etc.
Valve clearance is measured between the end of the tappet and the camshaft lobe. Adjustment is carried out as follows:
1. Turn the crankshaft (if the candles are removed, this can be done by the V-belt), until the mark on the belt pulley aligns with the TDC mark on the ignition adjustment plate. The piston of the 1st cylinder will be in the TDC position (see illustration below). If you now slowly turn the shaft from side to side, you will notice that the pusher of the first or fourth cylinder moves up and down, i.e. the valves overlap. If this happens with the valves of the 4th cylinder, the piston of the 1st cylinder is in the TDC position; otherwise turn the crankshaft half a turn.
2. Measure the valves of the 1st cylinder and all valves shown in the illustration, and record the clearance of each valve.
Measurement of intake camshaft valves (A) and exhaust camshaft (IN), when the piston of the 1st cylinder is in the TDC position.
3. To check the clearance, insert a feeler gauge between the tappet surface and the cam as shown in the illustration below. A sign of a correctly adjusted gap is that the probe is pulled tight at first, and then easier.
Check the valve clearance with a feeler gauge at the indicated location.
4. Turn the crankshaft half a turn so that the piston of the 4th cylinder is in the TDC position. Check that the noses of both cams of the fourth cylinder are facing up and check the valves (illustration below) in the manner described above.
Measurement of valve clearances when the piston of the 4th cylinder is in the TDC position.
5. If the valve clearances are within acceptable limits, you can install the removed parts. Otherwise, the appropriate clearance must be corrected. Please note that Nissan workshops use two special tools to change the shims. In any case, there must be a strong magnetic rod. The adjustable valve lifter must be pressed inward to remove the washer with a magnet.
6. Rotate the crankshaft so that the variable valve cam nose points up.
7. Using a small screwdriver, turn the pusher so that the notch on the edge points to the middle of the cylinder head.
8. Now push the pusher inward with the tool or a screwdriver and use a small screwdriver to move the washer sideways so that it can be removed with the magnetic bar. The assistant must keep the pusher pressed while doing this.
9. Using a micrometer, measure the washer thickness. Although the washer has the designation (TS 224 stands for 2.24 mm washer thickness), the washer must be measured as it may be worn. From the obtained value, based on the following formula, you can determine the thickness of the required washer:
- 10. N= R + (M-0.37) - inlet valves
- 11. N= R + (M-0.40) - exhaust valves
- «N» - the thickness of the new washer, «R» - the thickness of the former washer and «M» - the value of the measured valve clearance.
10. Shims are available in 50 thicknesses from 2.00mm to 2.98mm in 0.02mm increments. From this list, select the washer with the thickness closest to the value obtained. The thickness designation after installation must be at the bottom. When installing the washer, push the plunger in again and set the washer in place using a magnet and a small screwdriver.
11. Check all adjusted valve clearances after installing new washers. As already mentioned, the clearance should be checked with a warm engine.
12. Install all removed parts. Do not make a mistake when connecting the ignition cables, otherwise the engine will not start.