WN engine and JS engine prior to MY 1986
Examination
Warm up the engine to operating temperature (coolant temperature above +35°С, cylinder head warm).
Disconnect the throttle cable.
Disconnect the crankcase exhaust hose.
On the JS engine, disconnect the plug connector of the control pressure regulator and disconnect the vacuum supply hose from it. Loosen the control pressure regulator mounting bolts and move the pipes away from the cylinder head cover.
Remove cylinder head cover.
Turning the crankshaft, install each cam in sequence with the back of the head on the end of the pusher.
Using a set of feeler gauges, measure the gap between the back of the cam and the adjusting washer on the pusher for all valves in sequence.
Warning. It is not recommended to turn the camshaft directly by the pulley mounting bolt, as too much force can lead to a violation of the adjustment of the gas distribution mechanism.
Clearances in the valve drive mechanism
The gap between the camshaft cams and shims 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 adjustment of the valve clearance after repair should be carried out on a cold engine. Adjust the gaps if the check reveals deviations from the allowable values.
Record 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 shim will be the largest, thereby loading the valve lifters of the opposite cylinder, and adjust the valve clearance of this cylinder.
Using tool 2078, push the pushrods into the body of the cylinder head. Turn the tappet slot perpendicular to the camshaft axis and install a puller to remove the shims.
Remove the shim using a 10-208 puller or a thin blade screwdriver.
Measure the thickness T of the removed washer with a micrometer and calculate the thickness of the new washer using the formula:
Ti \u003d T + Zi-Zn,
Where:
Tn is the thickness of the new washer;
T is the thickness of the removed washer;
Zi - measured clearance;
Zn - nominal clearance.
Select an adjusting washer of the required thickness and install it on the pusher with the mark towards the pusher.
Remove tool 2078.
Adjust the clearances on the other valves in the same way.
Finally adjust the valve clearances on a warm engine if the initial adjustment was carried out on a cold engine.
JS engine from MY 1986
Since MY 1986, the JS engine's valve train has been fitted with hydraulic tappets to automatically compensate for valve clearances.
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