WN engine and JS engine up to 1986 model year
Examination
Warm up the engine to operating temperature (coolant temperature above +35°C, cylinder head warm).
Disconnect the throttle cable.
Disconnect the crankcase ventilation hose.
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On a JS engine, disconnect the plug connector of the control pressure regulator and disconnect the vacuum supply hose from it. Unscrew the mounting bolts of the control pressure regulator and move the tubes away from the cylinder head cover.
Remove the cylinder head cover.
While turning the crankshaft, install each cam in sequence with the back of the head on the end of the pusher.
Measure the gap between the back of the cam and the adjusting washer on the tappet sequentially for all valves using a set of feeler gauges.
Warning: It is not recommended to turn the camshaft directly by the pulley mounting bolt, as too much force may cause the valve timing to be out of adjustment.
Clearances in the valve drive mechanism
The clearance between the camshaft cams and the adjusting washers on a warm engine should be 0.25±0.05 mm for intake valves and 0.45±0.05 mm for exhaust valves; on a cold engine, respectively 0.20±0.05 and 0.40±0.05 mm.
Adjustment
The first valve clearance adjustment after repair should be performed on a cold engine. Adjust the clearances if deviations from the permissible values are detected during the check.
Record the clearance values Zi for each valve.
By turning the crankshaft, set the valve of one of the cylinders to a position in which the gap between the camshaft cam and the adjusting washer will be the largest, thereby loading the valve tappets of the opposite cylinder, and adjust the valve clearance of this cylinder.
Using tool 2078, press the tappets into the cylinder head body. Rotate the tappet slot perpendicular to the camshaft axis and install a puller to extract the adjusting washers.
Remove the adjusting washer using a 10-208 puller or a thin-bladed screwdriver.
Measure the thickness T of the removed washer with a micrometer and calculate the thickness of the new washer using the formula:
Ti=T+Zi-Zn,
where:
Tn - thickness of the new washer;
T — thickness of the removed washer;
Zi - measured gap;
Zn — nominal clearance.
Select an adjusting washer of the required thickness and install it on the pusher with the mark facing the pusher.
Remove fixture 2078.
Adjust the clearances for the remaining valves in the same manner.
Final adjustment of valve clearances should be made on a warm engine if the initial adjustment was made on a cold engine.
JS engine since 1986 model year
Since the 1986 model year, the JS engine's valve train has used hydraulic tappets to provide automatic valve clearance compensation.
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