How do I know if a used turbo is in good condition?

[sting0004]

Alright, well i hope this question isn't too noobish. How do I know how good a used turbo is? Rust doesnt matter on the exhaust side, correct? Any and all cracks are bad, or are small hairline cracks ok? Is shaft play when the shaft moves horizontally through its long axis or when it moves up to down or side to side parallel to its long axis? How much shaft play is tolerable? Is there anything concerning the turbo's blades that I should look out for, anything not obvious? These are just a few questions I have concerning the integrity of used turbochragers. Hopefully this thread helps other people who are looking to buy a used turbo, thanks alot, Matt

 

[machgsx]

Shaft play is movement on the horizontal axis. I can't say how much play would be acceptable.

 

[2GStreeT]

So will the shat Always have PLay in Vertical level?

 

[candela]

I think just about every turbo will always have a little play both directions. Heres a quick summary...

little bit of vertical is ok, any more than a little bit of horizontal is a pretty good indicator its going. Chips in blades is shitty and will effect performance noticably and take a lot away from its efficiency (dont ask how I know). Actually any damage at all to the blades is bad. Leaking seals is bad. Cracks arent always to bad. Most cracks wont really effect pefformance. If they go all the way through the housing then it ill hurt performance a little. If they are around the wastegate than they will probably continue on that path until it reaches the passage... then from this point you have a wastegate that constantly leaks. It can get even worse like my stock turbo did a long time ago and form, basically, its own 40mm hole or so, so its takes entirely to long to build any boost. Rust is nasty and almost inevitable on and iron part in due time, unless you basically clean it and coat it frequently all will rust eventually. Most can be ground off and even smoothed and get a a sorta polished look very easily so thats no biggie.