Attention! If the cooling system channel plugs fall into the cylinder block channel, it is usually impossible to remove them.
1. Using light hammer blows, knock the ends of the plugs out of the cylinder block so that the plugs rotate in the holes. Then remove the plugs from the holes with pliers (see photo).
2. Use a spatula to remove all remaining gasket material from the cylinder block, being careful not to damage the separating surfaces.
3. Remove the main bearing caps and take the bearings out of the cylinder block and caps. Write down the cylinder number to which the removed main bearing corresponds, as well as the part from which it was extracted (from the bearing cap or from the cylinder block bed).
4. Unscrew and remove all threaded plugs of the cylinder block channels. It is almost impossible to remove the plugs, so drill them out and re-cut the threads with a tap. When assembling the engine, replace all plugs.
5. If the engine is very dirty, it should be cleaned at a car service center with a jet of steam or in a hot chamber.
6. Additionally, clean all oil passages and holes. Blow out the internal passages of the block with compressed air.
7. If the block is only slightly dirty, you can limit yourself to washing it with warm water, detergent and a hard brush.
8. Use a tap to restore the threaded holes in the cylinder block (see photo).
9. Install the main bearing caps in place, tighten the bolts by hand.
10. Using a mandrel, press new cooling channel plugs into the block, after having lubricated the plugs with Permatex N1 sealant (see photo).
11. Lubricate the oil passage plugs with Permatex N₂ sealant and screw them into the cylinder block holes.
12. If the engine will not be assembled at this time, cover the cylinder block with a polyethylene cover.
The source of the article is available on the website ChevyMan.ru