Scrap all traces of gasket material from the cylinder block. Be careful not to scratch the surface of the block.
Remove the main bearing caps and pull out the bearing shells. Mark the liners from which cylinder, whether they were in the cover or cylinder block and set them aside.
Pull out all threaded plugs of the oil passages. Usually they do not get out, and they have to be drilled. For now, plug the holes with rags, and when assembling, put new plugs.
The cylinder block is usually steam cleaned in the workshop, but with care it can be done at home.
After cleaning with steam, once again clean all holes and oil channels using special brushes. Rinse the channels with warm water until the water comes out clean. Dry the block thoroughly and wipe all machined surfaces with an anti-corrosion oil
If the block is not too dirty you can clean it with hot soapy water and a stiff brush. Regardless of the cleaning method, thoroughly clean all oil holes and passages, dry the block completely, and apply oil to all machined surfaces.
Run a suitable tap through all threaded holes to remove corrosion, deposits and sealant residue. If possible, after this operation, blow out the holes with compressed air to remove the formed small particles.
Install the main bearing caps and finger-tighten the bolts.
Apply sealant to the new plugs and install them in the holes. Place the plugs in place using the bushing and hammer, the bushing diameter should be slightly smaller than that of the plug and hammer. Insert the plug slowly and stop when it is flush with the block. Make sure the plugs are not skewed and fit correctly.
Apply a non-hardening sealant to the oil passage screw plugs and screw them into the holes in the block. Make sure they are securely tightened.
If the engine will not be assembled immediately, cover it with plastic wrap to keep it clean.