If you hear a constant knocking sound from the valves when the engine is idling, the hydraulic mounts of the drive levers are faulty.
Replace the defective hydraulic mounts.
You will need: keys "10", "13", "17", "24"
Remove the cylinder head cover (see "Replacing the head cover gasket Niva Chevrolet").
Check the hydraulic bearings by pressing the valve drive levers one by one, trying to sink the bearing plungers.
The force required to sink the plunger of a serviceable hydraulic bearing is quite high, while in a faulty bearing, on the contrary, the plunger sinks easily.
When turning the crankshaft, align the mark on the camshaft sprocket with the mark (lug) on the camshaft bearing housing (see «Installing shafts according to marks Niva Chevrolet»).
Drown the chain tensioner plunger with a metal rod (e.g. a screwdriver)
Unscrew the bolt securing the camshaft sprocket (see "Replacing the Niva Chevrolet damper")
holding the tensioner plunger, remove the sprocket from the camshaft without disconnecting it from chain.
Make sure that the chain does not come out of engagement with the sprocket of the oil pump drive shaft.
Secure the sprocket together with the chain to the engine.
Unscrew the nut of the stud for fastening the camshaft bearing housing, which simultaneously secures the fitting of the oil supply pipe to the hydraulic supports, and remove the fitting from the stud
Move the pipeline to the side, carefully turning it in the rubber sealing rings of the ramp pillars.
Unscrew the remaining nuts securing the camshaft bearing housing, remove the flat washers located underneath them and remove the bearing housing together with the camshaft from the cylinder head studs.
To facilitate the reinstallation of the bearing housing with the camshaft, after removing them, try not to turn the shaft in the housing.
Remove the lever valve drive.
Unscrew the hydraulic support and remove it from the cylinder head holes in and the ramp racks.
Before installing a new hydraulic support, pump out any oil that has accumulated in the cylinder head hole.
If the oil is not removed from the cylinder head hole, the hydraulic support will not be able to be screwed in all the way and the valve drive will not work properly.
Install the valve drive lever and camshaft in the reverse order of removal.
Housing fastening nuts Tighten the camshaft bearings in the sequence shown in the figure.
Depress the plunger of the replaced hydraulic support, as you did during the check, until a gap appears between the valve lever and the camshaft cam.
Install all previously removed parts in the reverse order of removal.