Rebuilding your Turbo
Turbo Mini Forums

Having recently rebuilt my turbocharger, I thought it would be good to put a little guide up as its one of the only things not documented on the site. Please note this is for a T2 turbo, but the essentials should be the same for most units.

If you are just carrying out a rebuild/bearing replacement, you can reassemble your turbo without getting it rebalanced, but you must mark it carefully so ensure the rotating parts go back on as they came off.

Because I have changed my compressor wheel I am getting the whole rotating assembly balanced by Turbo-Technics.



You will need:

1 dirty turbocharger
1 rebuild kit
12 pointed socket to suit compressor wheel nut
Various circlip pliers
OIl
Degreasing agent
Torx/Allen bits




FIrstly, I have fitted a larger compressor wheel and hence have had to have the backplate machined to suit. You can see the machining below..



I didn't take many pictures of the strip down but it is pretty straightforward

1. Remove compressor housing by releasing the large circlip behind it, and the O ring seal.

2. Remove the turbine housing by undoing the 4 bolts and removing the semi-circluar plates, the housing should come off, but I found mine to be a bit stubborn, some penetrant and patience helps here, but be carefull not to damage the turbine wheel in the process.

3. Most important. Mark the position of the nut, compressor wheel and turbine wheel in relation to each other so that they can be put back on in the same alignment. This is only necessary if you are not having the unit balanced.

4. Undo the compressor wheel nut, which is a reverse thread! You may get a socket to fit the turbine wheel end nut, or mount
gently in a vice with some wood to protect it.

5. Once the nut is off, the compressor wheel should come off, if it is stubborn, use a small puller hooked on the backplate to push the shaft out towards the turbine end, until you can get your fingers under the compressor wheel enough to remove it.

6. Once the wheel is off, carefully withdraw the turbine and shaft assembly along with the turbine seal plate.

7. Now you need to release another circlip, this one holding the bearing cover in place, then withdraw the bearing cover and O ring seal.

8. Once that is out of the way, you will see the thrust bearing, there are 3 torx bolts holding the thrust bearing in place. Remove these and lift out the thrust bearing and collar. Note that it has oil ways on the back and must go back in the same way. You will also see that as standard it is a 270 degree bearing, and the collar can be slid out in the gap. If you fit a 360 degree bearing, the thrust collar arrangement is lightly different, more on that later.

9. Once the thrust bearing is out of the way, you will see the journal bearing which should come out with no fuss. Turn the unit around to the turbine side, to remove the journal bearing this side you will need to remove a very small circlip holding it in place. Very fiddly but with patience it will come out.

There are 2 more small circlips that stop the two journal bearings from sliding around, you can replace these for the new ones in the rebuild kit or leave them as you see fit.


Give the unit a good clean and degreasing ready for re-assembly.

1. Coat the new journal bearings in oil, and carefully insert one into the turbine side, until it reaches the inner circlip.

Now install the new outer circlip to retain it.




2. Looking at the turbine shaft, you will see a small piston ring just at the rear of the wheel. This needs to be replaced with a new one, and in my eyes is the most awkward job in the whole rebuild. Carefully remove it, clean the ringland and install the new ring.



3. Now the shaft can be re-installed into the housing, not forgetting the turbine back seal plate! Oil the shaft in the bearing area, and carefully slide it in. Now the tricky bit is to get the piston ring into the centre housing recess. Be patient, and carefully nurse it in.


4. Turn the housing back over making sure that the shaft doesn't fall out! Install the other oiled journal bearing into its housing, followed by the thrust bearing and collar. Now if you are fitting a 360 degree thrust bearing, the thrust collar comes in 2 halves, the smaller to be fitted in before the thrust bearing, the pictures will explain better. Make sure you oil it.





5. There is a second piston ring seal that fits into the thrust collar, remove the old one and replace.

6. Refit the three retaining bolts for the thrust bearing, then install a new O ring to fit behind the bearing cover,then the bearing cover followed by the retaining circlip, making sure it is seated well.






7. Now you can refit the compressor wheel, making sure to align it with the marks you made earlier. Refit the nut, backwards remember! and then give it a spin to ensure nothing is wrong so far.






8. Fit a new large O ring to the backplate before fitting the compressor housing back on.



9. Refit the turbine housing and retaining bolts.

Hey presto one rebuilt turbo!!

I hope this makes sense, if I have made any errors please correct me, I'm no expert.

Here is a comparison picture of my new compressor wheel and housing






Cheers to Nick for the photos

Edited by Kean on 10th Apr, 2009.

That compressor turbine wheel is going to push a lot more air so will it not increase the lag ?.
Really appreciate the guide to strip and rebuild -you never know when you may need ot !

Great stuff.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Nice one!! Really usefull.

just make sure if you do strip your turbo off and inspect/rebuild as done here, prime it with oil first. without doing so you risk running the turbo for a second or two without oil, while pressure builds in the system, which can cause serious consequences to the turbo. you can do this with a syringe filled with engine oil, directed into the oil inlet whilst slowly rotated in the shaft. i have seen a few turbos that have failed due to momentary oil starvation.

its also important to take angles of the relative position of the comp housing, turbine housing and bearing housing. the turbos drain their oil via the magic of gravity, so even if your exhaust inlet lines up to the manifold and the comp inlet lines up, the bearing housings drain may not, meaning you have to take it all apart again. the same is true of the actuator.

you still using this dude?
notice any more lag?

Hi mate

have been using it for the past year or so, no lag at all, and it produces masses of boost, only problem is with the turbine A/R I have, in high gears it surges its nuts off unless you are more than half throttle. On the strip it is awesome, just keeps pumping boost out.

I have been looking for a larger turbine to move the boost up the rev range a little and keep it out of surge, but I may fit a totally different turbo soon anyway, and this one may be for sale.

1152cc turboed mini clubman, most powerful 1.1L a-series?

http://boostmini.justboard.net/

Well I never really had any lag in the first place, and this was just the same, just flows a hell of a lot more.

are you using a mirrage manifold with this ? if so did u have to cut the block away to fit the compressor housing?

"Tuning should be a compromise between what is possible and what is necessary"

10)Thou shalt always quest for more power

No mods to block or housing on a mirage.

what compressor wheel and housing is it you have use there?

"Tuning should be a compromise between what is possible and what is necessary"

10)Thou shalt always quest for more power

rubicon: its a t2 he has hybrided using a different compressor wheel and housing not the t25 so i guess it depends on what housing he has uses

"Tuning should be a compromise between what is possible and what is necessary"

10)Thou shalt always quest for more power

thats right!!
doh

i just used the SAAB core and used my R5 turbo shaft,
i forgot about what he'd done

hi there..

just wanted to say thanks for the guide kean , it has helped me a lot.

i have almost completed the rebuild. im just having trouble with the bearing cover, i cant get it to go in all the way, its probably due to the "piston ring" is it just a mater of pushing it in? or is there some trick?

cheers

can anyone tell me how much movement is normal for a freshly built turbo? i did mine (the core so far) and its got zero on the thrust axis (360) but has what looks like by eye a half to one mm? im assuming that it needs some running clearance and that the oil will center it? my concern is that it may be a worn out housing?

c2 mad on mine it needed a small tap with the copper block to push it up the taper

Do you have to get the core balanced after a rebuild? If you replace the compressor etc?

Edited by Johnny on 2nd Mar, 2013.

ah right ok, how much does it cost to get it all balanced?

no idea mate maby pm Kean ?