General information
To compensate for the thermal expansion of the valves, there is a gap in the valve mechanism, which must be correctly set. If the gap is too small, the valve timing changes. Late closing and early opening of the valves leads to a loss of engine power, its uneven operation. In an extreme situation, the valves can be deformed from hitting the pistons, and the valve seats can burn. If the gap is too large, the valves open late and close early, i.e. the valve timing changes, the engine power decreases, the engine runs unevenly. The installation of valves is considered correct when they are impeccably tight, have an acceptable gap, and do not knock in the guide bushings.
Valve clearance can be checked and adjusted both on a cold and hot engine.
Check and adjustment
1. Remove the cylinder head cover (see illustration). Unscrew the oil screen (see illustration).
2. Set the gearbox to neutral position, tighten the handbrake.
3. Rotate the engine at the crankshaft pulley center bolt in the direction of normal engine rotation. In this case, the camshaft will also rotate.
4. Set the piston of the 1st cylinder to TDC. To do this, turn the crankshaft until the valves of the 1st cylinder overlap. «overlap» valve timing means that while the camshaft cam that controls the intake valve position starts releasing the valve lever, the cam that controls the exhaust valve starts pushing the lever to open the valve. The valves are closed if both cams point down and the bisector of the angle between the tops of the cams is vertical. At this time, the mark on the camshaft gear matches the mark on the housing (see illustration).
5. In this position, check the clearances of the following valves: exhaust and intake valves of the 4th cylinder, intake valve of the 3rd cylinder, exhaust valve of the 2nd cylinder (see illustration).
6. To check the valve clearance, insert a feeler gauge into the gap between the lever and the camshaft cam, while the feeler should slightly "pinch".
7. Valve clearance: for the intake valve - 0.2 mm, for the exhaust valve - 0.3 mm.
8. Turn the crankshaft 1 full turn in the direction of normal rotation, the valves of the 4th cylinder should close. The mark on the camshaft gear will rotate 180°and face up (see illustration). The TDC mark on the flywheel is now again opposite the pointer on the clutch box.
9. Measure the clearances of the following valves: exhaust and intake valves of the 1st cylinder, intake valve of the 2nd cylinder, exhaust valve of the 3rd cylinder.
10. If the valve clearances do not correspond to the permissible value, rotate the bolt of the corresponding lever using a special key (see illustration).
11. Install the oil screen, tighten the bolts with a tightening torque of 10 Nm.
12. Install a new cylinder head cover gasket, carefully and evenly tighten the cover screws.
Visitor comments