What do you think about rebuilt engines?

[junior]

are they reliable? and can give the original power and torque?, can change the characteristic paremeters of engine. i mean in here when i see a car with rebuild engine it seems so miserable, because it's sound changes, white oily smoke comes from exhaust pipe, engine character changes, torque in low rpm reduces, and it goes... so what about rebuilt engines in heavy equipments?

 

[Dozer575]

With any rebuilt engine it depends on who's doing it. I think that word REBUILT is so misused, to rebuild something that means it should be redone just as it was originally done from the factory. I think the big companys caught on to that misuse of that word and adopted the term, REMANUFACTURED. In the old days tearing down an engine or other main component was termed OVERHAUL and I think that is a more appropriate term for what everybody usually calls rebuilt. I've seen people say I rebuilt my engine in my car, when all they did was drop the pan and put some bearings in.
To answer your question there is no reason a REBUILT engine should not do exactly what a new one did or even better. In a true rebuilding situation you usually have much better quality people doing that work than you woud find on an assembly line in the factory. Also in the factory setting it is hurry up and get the job done and move to the next. You would find that type of rush rush deal at a big volume engine rebuilder too. These are the outfits that rebuild for places like Shucks, and even some of the big car companys. Also alot of automotive components are being rebuilt in places like Mexico etc.
I know GM has reman transmissions rebuilt there. So your best bet is to find a compentant guy that has a good back ground in doing such work. A person that will take the time to do the job properly. You don't want a guy that brags about how fast he is at doing a rebuild. Something to think about, F1 race engine outfits brag about how long it takes them to assemble an engine.
If memory serves it is like 80 hours, meaning 2 weeks. So yeah if those rebuilt engines you are talking about were built by an outfit that hammers out all they can in a day. Then what you describe will happen.