With a reduced gap, the valve timing changes, the tightness of the cylinder deteriorates, the engine power drops, it starts to work intermittently. In extreme cases, the valves or their seats are deformed or burnt out.
With an increased clearance, strong noises occur, the valve timing changes, the engine loses power due to insufficient filling of the cylinders, and its operation becomes uneven.
Due to differences in the coefficient of thermal expansion in different parts of the engine, the thermal clearance of the valves also depends on the operating temperature of the engine.
Attention! Valve clearances must be checked and adjusted with a cold engine.
Valve clearances must be checked every 10,000 km. The nominal clearance values for all vehicle variants are as follows:
- intake valves - 0.15 mm;
- exhaust valves - 0.15 mm.
Raise the rear of the vehicle and place it on stands.
Using a large screwdriver, remove the mounting brackets on the valve cover and remove the cover.
Valve clearances are adjusted in the sequence: 1st, 2nd, 3rd and 4th cylinders. The first cylinder is located in front on the right in the direction of the car. The corresponding marking is located on the engine cover next to the spark plug hole.
The clearance must be adjusted when the piston is at TDC on the compression stroke. In this position, both valves are closed.
Set cylinder 1 to TDC. To do this, remove the cover of the ignition distributor and turn the engine by the V-belt until the mark on the pulley coincides with the junction of the crankcase halves. At the same time, the middle of the movable contact of the distributor must coincide with the mark on the edge of the latter's housing. In this position, the thermal clearance of the valves of the 1st cylinder is checked and adjusted.
Insert a feeler gauge 0.15 mm thick between the rocker arm and its stem. If the thermal clearance of the valve is greater or less than the nominal value, loosen the locknut of the adjusting screw and adjust the clearance with a screwdriver. The gap is set correctly if the feeler gauge is inserted and removed with little friction.
While holding the adjusting screw in the proper position with a screwdriver, tighten the locknut.
Check the valve clearance again. To adjust the thermal gaps in
valves of other cylinders, you need to set the piston of the corresponding cylinder to TDC by rotating the crankshaft. Adjustment is greatly facilitated if the corresponding marks are applied using a scriber on the edge of the ignition distributor housing.
To adjust the thermal clearances of the valves of other cylinders, the crankshaft must be installed according to the markings shown in the picture, each time turning it to the left by an angle of 90°.
Clean the valve cover with gasoline, install a new gasket and secure the valve cover with a clamp.
Check the oil level and test drive to see if the valve cover gasket is leaking oil.
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