Ok so I am buying a used ebay turbo for 25 dollars to use for moch up purposes on a spare engine. It smokes kinda bad so im thinking the seals are trashed. My questin is, What is it that makes them fail? is it just cheap bearings and seals or cheaply casted housings that do it? Just out of curiosity what if one was to rebuild one with a quality rebuild kit? Like I say im going to buy it anyways for moch up but i figured id ask even though Im pretty sure i know the answer.

the cheap ebay turbos use poor quality center housing parts. i also purchase these cheap ebay turbos but before i use them i purchase a quality rebuild kit and swap out the junk. never had a problem with them after that. ive used them on cars, trucks and motorcycles so they have seen all kinds of abuse.

If you rebuild it wiith a quality rebuild kit... it will most likely be fine.. however I have also heard of the cheap no-name turbos cracking housings... but if you get a cheap refurbished Garret for example, you know the housings are atleast solid, just needs new internals. If you are on a budget and don't care about risking it, go for it, but I wouldnt even bother running a new eBay one without a rebuild beforehand.

No im certainly not going to spend the money on a new one. Just running things through my mind. Figured since im buying it for moch up if its rebuildable why not. Thanks for the info.

I never thought of this, but it is a good way to get a decent new turbo for not much money.
All exhaust castings will most likely crack, its just a matter of time.
The cheap turbos run about 200, and then add a rebuild on top .....
But for around 400-500 for a new reputable internal rebuild, I would say go for it.

$25 dollar turbo = paper weight