Adjustment of thermal gaps in the valve drive is required for engines K7J and K7M.
For the K4M engine, valve clearance adjustment is not required, this engine is equipped with hydraulic valve clearance compensators
Hydraulic compensators ensure backlash-free contact of the camshaft lobe with the valve.
To compensate for thermal expansion of the valve relative to the valve lever in the K7J and K7M engines, a gap between the end face of the valve end and the lever is set by design.
With an increased gap, the valve will not open fully, with a reduced gap, it will not close completely.
We check and adjust the gaps when a characteristic knock of the valves appears.
A loud knock at the top of the cylinder head.
Be sure to adjust the gaps after repairing the cylinder head.
Gaps should be measured on a cold engine, approximately 20˚ C.
The gap should be 0.10-0.15 mm for intake valves.
For exhaust valves, the clearance should be 0.25-0.30 mm.
The intake valves are closer to the windshield relative to the car body.
A row of exhaust valves is closer to the radiator of the engine cooling system.
To measure the valve clearances, remove the cylinder head cover.
We unscrew the spark plugs to make it easier to scroll the crankshaft.
Remove the top timing cover and set the top dead center of the first cylinder at the end of the compression stroke ( see the article on replacing the timing belt).
We take into account that the first cylinder is located next to the flywheel.
Cylinder order 1-3-4-2.
The clearances on this engine are adjusted in pairs, if you set the TDC of the first cylinder, then we adjust the clearances on the intake and exhaust valves of the first cylinder.
Then we turn the crankshaft clockwise by 180˚, and adjust the clearances in the third cylinder, etc.
With enough precision to adjust the clearances in the valve train, the camshaft can be set to the desired position, controlling it visually.
The camshaft must be rotated so that the heels of the rocker arms of the drive of both valves of the cylinder, which is being adjusted, rest on the back of the camshaft cams, and the rocker arms can be moved by "swaying" within the gap.
We check the gap with flat feelers between the ends of the valve stem and the adjusting screw.
The probe should move in the gap with little effort.
If the gap is different, then use a 10 key to loosen the locknut of the adjusting screw, holding the screw from turning by the flats (you can use an adjustable wrench as in the photo).
Then, by turning the adjusting screw, we set the desired gap.
Tighten the locknut while holding the adjusting screw with a wrench.
Check the gap again and repeat the adjustment if necessary.
After adjusting the clearances in all cylinders, you need to turn the crankshaft again and check the clearances again.
After adjusting the valve clearances, we assemble all the parts in reverse order.
Start the engine and warm it up.
Listening to the operation of the valves. The sound of the engine should be smooth, without knocks and puffs.
