What Is a Rebuilt Engine?

Many sellers who advertise automobiles as having "rebuilt" engines fail to mention the extent to which the engine has been rebuilt or what broke to prompt the rebuild in the first place.

Blueprinting

  • Another word for a rebuilding an engine is "blueprinting." This refers to the practice of returning and engine to its factory tolerances and specifications, or "blueprint."

Rotating Assembly

  • In general, a basic rebuild is the replacement of the engine's rod and main bearings as well as the piston rings and gaskets.

Over-boring

  • A popular practice when rebuilding is over-boring the cylinder walls to return them to factory smoothness and roundness. This requires replacement of the factory pistons with slightly larger units.

Replacement

  • Many engine rebuilds also include a new water pump, alternator, spark plugs, spark plug wires, ignition coil(s), fuel injectors, oil pump and camshaft.

Performance Rebuilds

  • Most performance rebuilds include stronger pistons, a more aggressive camshaft, new valve springs, a new or modified intake manifold and tubular exhaust "headers" in place of the factory manifold.