If the noise is clearly manifested, then the camshaft and pushers should be replaced.
Removing
1. Remove the cylinder head cover.
2. Remove the rocker with the roller and remove the rod in the cylinder in which the operation of the pusher is accompanied by abnormal noise.
3. Remove the side cover and remove the pusher (And).
4. Store pushrods in the order in which they were installed.
Examination
1. Rinse the pushers one by one.
2. Check the wear of the thrust surface of the pusher, the saddle of the rod and the condition of the side surface. Replace pushrods if metal pickup, scratches, or increased concavity are observed on the thrust surface.
3. The thrust surface of the pusher has a concavity with a large radius of curvature (the photo on the left shows a check for the concavity of the thrust surface of the pusher). If the thrust surface is heavily worn (photo on the right), the camshaft and tappets must be replaced. If the side surface is worn (which is unlikely), then check the condition of the holes in the cylinder block. Check the condition of the saddles of the rods and the ends of the rods themselves.
4. The camshaft and pushers change only together. Put the removed pushers in their original places.
Installation
1. Lubricate the tappets with molybdenum grease.
2. Lubricate the bores in the cylinder block with engine oil.
3. Install pushers.
4. Install the rest of the removed parts in reverse order.