Engine Rebuilding can cost less than replacing it.
Assuming the original engine is rebuildable and the amount of machine work required to restore it is minimal. Most of the savings comes from the labor you put into tearing down the engine and then reassembling it.
Another reason for doing your own engine rebuilding work is to control the quality of parts and work that goes into the engine. This is something you cannot control when you buy an engine from an outside source. It may be top quality, or it may not. But you do not want to find out “the hard way.” The truth is, some remanufacturers reuse a much higher percentage of parts than others do, obviously for cost savings purposes.
You can also save by buying the parts you need in an engine kit rather than individually. A kit gives you everything you need in one box and reduces the chance of mismatching parts. The parts in a kit usually include bearings, rings, pistons, timing chain and gear set, valve seals, gaskets, oil pump, camshaft, lifters and other miscellaneous parts.
You can usually get OEM or better quality parts in most kits, which may be better than the parts found in some remanufactured engines.