hey guys i just want to know the proper method for checking a turbo to see if its in good running order or needs rebuild. Also would a large chip and some small hairline cracks around the exhaust inlet ports(name?) pose any major problem?

Incase the name was wrong i mean the 2 different shaped inlets that get bolted onto the exhaust manifold.

 

To check the stock turbo you should pull off your Turbo Inlet Duct and spin the turbine with your fingers. It will move with little pressure not just blowing on it like a PINWHEEL but once it does start to move it should be able to spin 1.5 times or more. Try to see if it moves about in any direction. It shouldn't move significantly (up, down, left, right, in, out) and should definitely not come in contact with the surrounding housing. If it's in there fairly tight it should be good. If not then it's time for a turbo rebuild or upgrade.

I don't know about the exhaust inlet ports. You shouldn't have any cracks but if you do, I don't know how long it will last.

 

You want to check for play.


Front/back(in & out) If there is play that is bad, the more play the worse.
Up and down/side to side if there is a lot of play that is bad.
If there is oil dripping into the compressor/turbine housing and you didn't spill any that is bad(seals are goin)

Cracks/deformations on the wheels are bad too as they need to be well balanced when they do 50k-100k-150k rpm.


Cracks on the housings/manifold are also bad, but i'm not versed at all in how bad or critical they are.



I hope i dind't get anything wrong but i'm sure i'll be corrected if I did.

 

it also should not have oil dripping out of i like mine did

 

wow i want to check my turbo now!

 

THe cracks.. You're talking about the oval shaped inlet ports on the bottom of the hotside (turbine) of the turbo unit, correct??

As long as the cracks are small, and do not go completely through to the outside, its ok.. preferably, there should be no cracks... BUT, this is the real world and 15 year old hunks of cast iron exposed to 1500+ degree heat all the time, tend to crack!!! As for the chip.... hmmm.... don't like that idea.. (where did the material from the chip go??????) but again, if its very small, it shouldn't be a problem.

Post a pic of it, thats the best way to get advice on the cracks!!!!!

Play.. the stock turbo rides on oil bearings... what that means is that the shaft spins on a thin film of oil while its rotation and, theoretically, doesn't contact the brass bearings... (yeah... right)... so.... when there is no oil pressure, the space that was taken up by the oil is now free, and thats where shaft play comes in... there HAS to be a very small about of play in the shaft to allow for the oil film for the shaft to ride on when the engine is running. BUT... it is a very small amount... you should be able to FEEL the shaft move from side to side and up and down when the turbo is cool and the motor is not running... if it clunks back and for and it visibly moves around a good bit... bad bearings.. The shaft should not move in and out to any great extend either.

 

HOLY CHRYST!!!!!!!!!!!!!!!!

 

Easy checks

Pull TID off and pull back and forth on the turbo to see if it can push in or out. That kind of play is BAD.

Next try side to side play. If it can touch the compressor cover then it's obviously bad.

Then the Harder but needed check.

Remove the hotside housing. Look on the hotside for cracks on the part which is closest to the turbine. You don't want any cracks there because they will expand when heated and start to eat into the turbine.

Cracks on the dividers inside the housing are normal.

BTW www.turbosdirect.com rebuild my turbo. Great guys and a great price. The turbo has 32k on it and has perfect play still

Here's a pic from a S5 housing I bought with the bad crack.

 

Ill take some pics tonight. There is no real play that i can tell but ill double check when i get home. Its a s4 turbo by the way, are the 2 ovals supposed to be different sizes? They dont seem to be in that pic above even though thats an s5.

 

I just made a more specific circle. Ignore the larger one.

 

IYeah.. its part of that wonderful "Twin Scroll" thing that maZda came up with.

Bryan at BNR hogged those ports out so much when he did my tubro that i couldn't even tell you what they looked like before....

 

LOL i asnt referring to that, thanks for the replies though.