2. Scrape off any traces of old gasket material from the mating surface of the block. Try not to leave streaks.
3. Remove all caps and oil gallery screw plugs from the block. Plugs are usually very tight, so they may need to be drilled out and re-threaded in the hole. When assembling the block, the plugs should be replaced with new ones.
4. If the external contamination of the engine is severe, it should be taken to a car service workshop for steam cleaning or heat treatment.
5. After returning the block from the workshop, thoroughly clean all oil holes and galleries again - special cylindrical brushes of a special shape are produced for this purpose (ask at car accessories stores). Rinse the cavities and channels with warm water, - continue flushing until clean water begins to flow from the opposite side of the block. Dry the block thoroughly, then lightly coat all machined surfaces with light oil to protect them from corrosion. If you have access to a compressed air source, use it to speed up the drying process of the block and blow out hard-to-reach cavities and channels.
Attention! Remember to wear protective goggles when working with compressed air!
6. If the unit is heavily soiled or slagged, brushing with hot soapy water should be resorted to. You should not try to save time by carelessly cleaning the unit. Regardless of the method chosen, follow the thoroughness of cleaning hard-to-reach cavities, channels and holes. Finally, dry the block and lubricate the machined surfaces with thin oil to protect them from corrosion.
7. Drive all the threaded holes in the block with a tap of the appropriate size in order to ensure that the torque wrench indicator readings correspond to the actual tightening forces of the fasteners when assembling the engine. If possible, then blow out the driven holes with compressed air, removing all small debris and chips from them. After finishing the holes, go through the threaded part of the bolts with a lerka.
8. Reinstall the main bearing caps by finger-tightening their fasteners.
9. Lubricate the threads of the new plugs with a non-hardening sealant and plug the holes in the oil galleries with them. Check the tightness of the plugs.
10. If you are not going to assemble the engine immediately, place the block in a large plastic bag to protect it from contamination.