TheShodan

iTrader: (14)

I just wanted to thank Justin from DSMtuners (JusMX141) for a lot of this, but its still relevant to those who buy used turbochargers regardless of company and model.. Of course eBay has its own risks when their turbos are new, but this is for Used turbos. I added a couple of revisions in his quote for clarity so hopefully he doesn't mind. Hopefully this is useful for people.

"Everyone's been in a position where they come across a hell of a good deal on a used turbo. There are a series of things you should look at before you buy.

• Shaft play. This determines how well a turbo has been lubricated. There should be NO noticeable in/out shaft play (less than .002" by measurement), and as minimal up/down shaft play as possible (less than .014" on most turbos).
  
  On a journal bearing turbo, the bronze journal bearings ride on a film of oil so if the turbo has sat off the car for a while, the oil has drained away from the bearings. You should turn the turbo upside down and pour a small amount of motor oil into the oil drain flange and allow it to flow into the journal bearings before you get a final measurement of up/down shaft play.
  
  
• Bad oil sealing rings. If you look at the turbine wheel and it appears WET, the turbine shaft sealing piston ring is bad. It is more common that the turbine shaft sealing piston ring will leak before the compressor seal because of the extreme temperatures the turbine seal sees. The most common killer of these rings is excessive shaft play.
  
  
• Damage to the turbine or compressor wheel(s). It is more common for there to be damage to the inducer of each turbine than the exducer, (and the opposite for the turbine side) so be sure to examine both wheels very well. Remember- the inducer of the turbine wheel is only visible by peering into the turbine housing inlet (the flange that mounts to the manifold.)
  
  
  
• Exhaust housing cracks. Most cracks appear on the interior of the exhaust housing. Usually, these cracks are from the rapid heating and cooling that the housing sees, and they generally will not effect performance of the turbo. However, if cracks are present, be sure they aren't the whole way through where the housing will leak or cause the wastegate flapper (if internally gated) to not seal properly.
  
  
• Check all of the mounting holes for stripped threads or broken hardware. This is pretty self-explanatory.
  
  
• If possible, for internally-gated applications, check the wastegate actuator for smooth operation and make sure the flapper door seals tightly against the housing. I typically test the actuator of every turbo I rebuild by applying 20psi into the hose nipple with a rubber-tipped blowgun. A Mitsubishi actuator has about 1/3 of the travel of what a Garrett actuator does, so don't be surprised when the flapper of a Mitsubishi turbo opens less than 1/2 inch.

A few things to remember:

• Don't bother asking mileage. Many times a turbo with high miles that was well cared-for will be in better shape than a turbo with low miles that was abused. You will know how well a turbo is cared for if you check it with the steps listed above.
  
  
• Ask the owner for the history of the car that the turbo was removed from. If the turbo has just been pulled from a car with a blown engine, STAY AWAY! The inside of that turbo is so full of metal that it won't last 20 miles.

These are photos of a thrust plate that were taken from a Bullseye T04B V-Trim that had very low miles but came from a car that blew the engine with the turbo installed. You can see what I mean here:


The thrust plate is totally loaded with shavings.



Above is the V-Trim's thrust plate next to a new T3 thrust plate. You can clearly see that the oil passages are totally clogged. The journal bearings didn't look much better.

Thanks for reading my post"

-JusMX141 cc The Shodan

NZXTInerTia

I figured this was a question. With my recent blow with disaster the words "Shaft play" instantly came to mind.

Nice read, thanks for posting!

wantboost

iTrader: (2)

Use my pictures showing the cracked thrust retainer and such, good example of what happens when a turbo is pushed past its limits. And remember my unit had in spec shaft play and no seal leakage/failure


Mac, I have to go beat our 600rwhp c6 z06 around Atlanta Motorsports Park today but once I get home and on a pc I'll add my own information/experiences, pictures and other things to look for that you can add to your main post (pick and choose/edit the info if you like, I won't care lol )

Hopefully this stays on the first or second page, gets stickied or atleast added to the FAQ once we get all of the proper info, real world examples as well as pictures and such

Muckman

iTrader: (2)

The "no shaft play" statement concerns me. In my experience every turbo Ive owned had some shaft play when not under oil pressure. I think this trips up alot of people. They think any shaft play means the turbo is damaged when some is normal. Perhaps we can clear this up?

lsturbo33

Good thread for the people buying used turbos!!!

twkdCD595

I think the problem is people misunderstanding and not knowing the difference between appropriate bearing clearance vs actual shaft play.

LightningTeg

Correct me if Im wrong:

Journal bearings: There should be little to no "thrust" play. That is, in and out. Some axial shaft play is normal as long as the wheel doesn't contact the housings.

Ball bearings: Very little play in any direction.

You can tell when a turbo is effed generally.

TheShodan

iTrader: (14)

That's not a problem. I understand exactly what you mean, as this can get confusing. But I've also found that when these little "guides" are created, no one reads them that well anyway, and make it subject to a lot of weird interpretations.

Perhaps what I'll do is edit it, with ALL of my terms.. I just wanted to give Justin some credit for having it as a "sticky" on the DSM forums.

Muckman

iTrader: (2)

Exactly. Thats my point and its hard to explain that to someone who doesn't have the experience.

TheShodan

iTrader: (14)

Well, see, that's what I mean.. you just used the same term for a different description, (Axial "in & out", while Radial is "shaft play") and although you all know I like proper terminology, this was more of a quick reference, and not a full guide..

Ball-bearing cartridges with carbon cages like the GT(X)-R series will have a slight amount of axial play after some use, due to the fact that bearings being made of steel, and start to wear down after a good amount of cycles, even though there usually isn't any radial movement. Remember, these ball-bearing cartridges do create additional FRICTION on the system, even more than a journal bearing one. That friction creates heat, and a slight amount of weardown, but it doesn't go to "oblivion" where the turbo is useless. Again, this is why I was trying to keep this simple.. But I see your point.

I'll see what I can do to make this still more technical without making people rub their eyes in pain a bit.

SiRCiviC94

This info is all correct. Garrett units have minimal play but once oiled are rock solid which I like. Can't say the same for eBay units scraping the housings and smoking oil

v8killaz

most important part is buy from trusted people. dont buy the turbo if you Don't know the history. ask for receipt or where they bought it from and when.

without taking the turbo apart you dont know if its good

OneBadTurboCRV

These days, if you trust a receipt as solid proof, you are a fool. Anything can be bought and returned or even copied from another purchase to try and show as legitimacy evidence. It is great giving "credit", but when the information barely covers half of the concerns what help is it actually? We all know some kid is going to use this as a checklist. The problem is the list is incomplete. There are other major concerns like wheel damage, overheating/lack of lubrication, housing cracks, and most of all - the turbo is actually what they say it is.

I understand that If you are using this guide, you most likely don't know much about turbos to begin with, but we need to keep the demographic in mind when doing these. Being able to handle the turbo and break it down for the best deduction possible is not normally plausible, but there are areas of concern. Let's face it, most people you purchase used things from are strangers or a friend of a friend crap. As with buying anything - use common sense. This isn't something that you are going to magically have from reading a write-up. If something doesn't seem right, it most likely isn't.

PS - I am in NO way trying to take anything away from this, I just feel that it is extremely rough and far from finished.

TheShodan

iTrader: (14)

Then finish it N3V3R.. Take the reigns on this one..

It's getting rather annoying when I have more complaints than additional info, yet nothing like this exists in the forum. I have no problem with constructive critique, but if its all about context of what's missing, then people need to man-up and start filling the blanks themselves if they feel its more beneficial..I could be concentrating on the real information on my site instead of devoting time to do it here. I'm about to be done with creating threads because of this, in which I could benefit more rather than trying to assist with another sticky.

ONE..

2000GSRTypeR

Please don't feel this way Mac, you are one of the few knowledgeable/helpful people on this forum.

OneBadTurboCRV

I have already stated I don't have your knowledge. Hell, my PM shows it. I was just stating that as with everything there is a lot more to it and people need to be aware that just because a few things may check out, doesn't mean everything else is OK. You guys are right, I need to just "GTFO" and finally move on. I don't even own any ricers anymore anyways. It's not like I benefit the "community" like you do I guess anyways. I insist, it is all yours - I am done.

Yeah yeah, good riddens, I know.

wantboost

iTrader: (2)

I'll pretty much be heading this thread with loads of info and pictures, examples, and loads of information once I get my pc back from being cleaned from the fire

Get ready for information overload lol

Balor_Gr

Chinese say an image = 1000 words.
So what would be the reccomended gap created by pushing the comp wheel side to side (NOT default middle position to side) in mm ?
Its supposed to be bigger at ball bearing turbochargers as far as i know.
I hope the picture below helps.
(my drawing skills suck)

B and B

iTrader: (3)

post link...

Damn...

TheShodan

iTrader: (14)

In due time....

wantboost

iTrader: (2)

Yea apparently smoke damage includes carbon ash and whatever else is floating around in the air. It killeda 7, 000 dollar projection tv too

Atleast the house didn't totally burn (I say that with a grain of salt stuck in my crotch lol)


In response to the shaft play question. There's a specification when new but no real number wheb used. If it doesn't hit the housing and it doesn't blow oil then shaft play is of no real issue

Balor_Gr

Ok i didnt made a new thread cause we could use this data for educational purpose.
I bought this turbo after it was send to a big turbine service company for check up.They said the turbo is "like new" after they checked it.
The funny part is AFTER i bought it i saw this think inside the compressor housing.Its a strange stain.Im not sure if its oil cause it doest seem to follow
the oil leak path ive seen at other turbos.The turbo has almost zero shaft play.
I tried to test-remove some with a tiny amount of soap that cleans oil
I rubbed it a lot and it almost didnt cleaned.Small difference.
What do you guys think?






Normaly if the turbo blows oil the liquid follows a circular patern across the neck of the compressor like this video right? ( ) Sorry about my english btw.

TheShodan

iTrader: (14)

I think I've seen about 20% of any used turbo have "stains" in and out of both the compressor housings and backplates.. ALL were because they weren't cleaned properly. Get some Automotive simple green and try again. I don't think its anything to worry about.

chuwi_pty

Great info!!!

jdmthreadz

Excellent write up. This answered all my questions