Remanufactured, Rebuilt, Overhauled, or Repaired?
Outside the commercial transportation industry many people don’t know that diesel engines commonly last 300,000 - 400,000 miles before getting a little tired. With busses and trucks made to last easily more than a million miles, it’s common practice to swap or ‘refresh’ an engine and keep going for many more hundreds of thousands of miles.
Let’s look at some differences between Remanufactured, Rebuilt, Overhauled, and Repaired Diesel Engines.
Deciding whether to install an OEM-supplied remanufactured engine or use an independent rebuilder to perform a rebuild can be a tough choice. But there are compelling reasons to consider an OEM remanufactured product, according to Jim Morrow, president of Detroit Diesel Remanufacturing Corporation.
“First of all, let’s clarify the difference between a remanufactured engine and one that is rebuilt. Our reliabilt engines are totally remanufactured, returning them to the latest blueprint specifications and tested to original equipment standards,” explains Morrow. “The typical rebuilt engine is only repaired to the level of failure. That means any components beyond this level are left intact. And testing procedures often vary among individual rebuilders.”
More at: [Remanufactured vs. Rebuilding is Really No Contest / The Auto Channel]
Fast Fred, in a curiously non-sarcastic mood, 
writes:
Folks’ idea of a “rebuild” varies.
To me it is removing the engine, cooking the block clean, magnafluxing for cracks, sending it off for a machining alignment, checking the crank & rods for straight, etc etc.
It comes back as close to NEW as can be.Some folks believe a seasoned block will run longer than a new one as the stress is relieved before re-machining it true.
For some tossing a set of bearings in the bottom is a “rebuild.”
For others its a set of cylinders that is a “rebuild.”
Rebuild is just a word — getting the “build sheet” with a rebuilt engine that gives what was done, and the current parts (crank .020 under rods .040 over etc.) will allow one to figure out if it was a rebuild, an overhaul, or just an expensive repair job.
Rebuilt — everything taken apart down to the basic castings. Castings tested for cracks, alignment and cleaned (usually acid hot tanked). Then factory rebuilt or new parts installed in engine. Usually can get a factory rebuilt warranty when this is done.
Overhaul — take engine apart and see what is worn out and replace only what is worn. Usually keeping the same crank and camshaft, replacing cylinder liners with factory rebuilt pistons with new rings, (commonly called cylinder kits, sometimes only installing new rings) testing injection, rolling in new bearings and replacing what doesn’t come up to specs.
Repair — only replacing what is broken to make the engine run again.
In my opinion, considering the low mileage we do (under 100,000 miles-many times for the life of the conversion) an overhaul is usually enough.
The problem is that not everyone agrees with or adheres to these definitions.
One has to always ask for details (in writing is best) to be sure — each mechanic has a different definition.
