How-To: Rebuild your T28 Turbo!

Thread in 'Technical Questions' started by Vova, Jun 23, 2008.

  1. Vova

    Vova Member

    Apr 28, 2008
    Likes Received:
    Edit #4: Although due to a early spotted oil leak the shaft has 'some' play the turbo has been running about 1200KM mostly doing mountain runs and Autobahn top speed runs pumping out 1BAR till 5300~ and gradually falling back to .7 at 6500 holding that to red. The lack of boost I think is probably the play and partly grounded blades that probably touches the inner housing a few times.

    However, it seems it is starting to smoke again at extensive idling, you can smell it too. That I suspect is the quality of the rebuild kit but it may also be something different to be blamed to why the seals went (if they went). The seller is still good though, he tried helping me out all the way, so kudo's for that.

    Another thing, the stupid snap ring came loose again, probably my fault when re-mounting it, I bodged it now by hammer a piece of screwdriver between it and the water bolt to keep it from having play, has worked for 400km now.

    Looking back at it, I wish I just bought a new one.

    / Edit

    The rebuild can be done by anyone who has some spanner experience, however if you are a total newbie, I'd recommend to do it with someone experienced because as a newbie, you tend to make foolish mistakes (like me) which can be easily prevented. However, whatever your skill level is, some special tools are needed which I will explain later.

    I used these guides to get an impression of what to do.
    09.10.2005: Garrett T25 Turbo Rebuild -
    T25 Turbo Rebuild - Forums

    They have their (in my opinion) flaws and good points, I have borrowed some of their pictures as mine weren't all succefull, I'm sure they don't mind as I'm not using it to make a profit but to help people.

    What do you need?


    - Turbo rebuild kit

    I had a look around the net and found some 360 degree bearing kits, or other kits but didn't trust them as they looked Chinese. I bought this kit, it was very complete however the quality is probably lacking as the turbo is smoking again after ~1000KM.



    eBay Motors: T2 T25 T28 DSM Deluxe Turbocharger Turbo Rebuild Kit (item 160244336344 end time Jun-01-08 13:56:21 PDT)



    - A big, strong snap-ring-plier

    To get the main, compressor housing snap ring out. And I mean a strong one. I was lucky to know a guy who runs a engine-overhaul shop who let me borrow his and some other of his tools like the green plier you see in the pic.

    - Small needle-nose-snap-ring-pliers

    To get the little snap-rings / circlips, whatever they are called and piston rings, like the red one in the pic above.

    - 13mm spanner

    A ring + open end to get the compressor-bolts and exhaust housing loose.

    - 14mm spanner and/or Vice Grips

    To hold the exhaust-turbine shaft so you can undo the front compressor turbine nut. The 14mm fits however a size júst smaller than 14mm is better. Maybe some inch-sized one fits. Vice grips might do the trick as well, which is what I used.

    - Torx

    You need a small torx, I don't remember which one but it was very small to undo the thrust bearing's t-screws. One guide mentions its a T-15 but don't take my word for it.

    - (rubber-) Hammer, pick tools, other misscelanous stuff

    Well, in a perfect world thins come undone when you loosen the bolts, however in our car world, they don't so a hammer, a pick, a screwdriver usually does the trick. I used Snap-on dentists picks to get the bearings out but there are plenty of ways so its not needed persé. A rubber hammer is also needed.

    I rarely to never use penetrating fluid. I don't believe in it. In my opion oil cannot crawl into the rusted thread inside and help. Its only good to lubricate when mounting so it slides in easy. However oil, also attracts dust, sand and other unwanted bodies which is why I rarely use it.

    - Torque Wrench (not needed)

    I tried using a torque-wrench when tightening the nut on the compressor-side but it somehow didn't work, the force I was setting was way more than the set 20N, this being a 100$ wrench, I'll explain why later.

    Getting Started!

    My guide will dissasemle the turbo with the (braied flexi-) oil line still attached, so you don't have to replace the copper rings. If you still have the stock line, I recommend you get the flexi braied one not only is it better, fitting it is tons easier. The guid starts with the turbo complete still attached to the manifold and downpipe.

    A good word of advice here is to put everything you take off in order, so you can assemble it in the exact, same, sequence.

    Step 1: Seperate the turbo

    Now this guide: as mentioned above does it good, by undoing the 4 exhaust housing bolts (fig 3+4) against the centre catridge (fig 5), they push the exhaust housing off.

    However, it forgets one handy thing. Mark the compressor housing position relative to the exhaust housing. This way, you will have the oil drain and actuator in the right position during assembly again.

    You can undo the "turbo" from the exhaust housing with the manifold and downpipe still attached to the e-housing. This way you don't need to replace the gaskets if they are new (like mine were). Now when I say "turbo" in this aspect, I mean the compressor housing with the centre assembly. When you undo the 4 bolts holding the exhaust housing, you will slide the "turbo" out of it.

    Step 2: Undoing the compressor housing

    If step 1 succeededs, you should have ended up with this:


    Now take your big pliers and undo the snap ring pointed by the red arrow. Now this will be tricky and difficult if you don't have the pliers for the job.

    When the ring is off, the compressor housing should come off (perfect world..NOT!) but it won't, so tap it off evenly with a rubber hammer. Be carefull. Because the blades in the housing run a very small tolerance to the housing, so it has to come off straight and not in the slightest angle. If it will, it will scrap a blade or worse, bend it, almost happend to me when refitting it. Scraping it, is removing material = causing imbalance = dead.

    When the housing comes out, you can see a big O-ring around it, you can go ahead and replace it now. Clean the area of the O-ring before placing the new one.


    Step 3: Marking, marking, marking!

    Now as I mentioned before, I did not rebalance the turbo by a (way to expensive) company, which is a textbook procedure. Instead, I tried to preserve the original balance by putting marks and it worked! You need to do this before you even take the nut off the shaft.

    You need to mark the position of the compressor wheel relative to the shaft. First I made marks of the wheel to the housing. I always make 2 or 3 marks in case one gets wiped off. Than I made 3 marks with yellow bright paint on top of the shaft first (the nut was still on unlike the pic). Let them dry and than made preciser marks with a pen. When I took off the nut I redid the marks again. This needs to be done very precisely!


    Step 4: Removing the turbine wheels and shaft

    Removing the nut

    First we are going to remove the nut on the compressor side which hold the wheel. The exhaust side is a one-piece with the shaft. The nut is some strange one, a 8mm socket fits, but isn't optimal, vice grips fit but are big and clumsy. I used a special socket that I don't remember but it fitted perfectly, comparable to this:


    The important thing to remember, is this nut goes off clockwise as its left-hand thread.

    Take the 14mm spanner and put it on the exhaust side to counter rotate the shaft. Put whatever you found for the nut on it and undo it clockwise. Carefull! The rebuild kit provides a new nut so you can use vice-grips if nescerry, but I don't recommend them.

    Removing the wheel and shaft with exhaust wheel

    Now again, in a perfect non rusty world, the compressor wheel should come off after undoing the nut. Most likely wont. First option, is the easy way, that worked for me, thankfully. By just using my hand and clamping the butter-like-easy-to-bend wheel with my fingers I tried lifting it up while rotating it back and forth, clamping it very lightly, almost no force.

    Another way:


    By putting the gear puller on the housing and screwing it in, you push the shaft down thru the compressor wheel. Now the shaft is down a few centimeters, you can push the shaft back in from the other side and the wheel comes up creating space underneath where you can put your hand and try to lift the wheel off the shaft.

    Well if you did it my way and the comp wheel is off with no damage, you can tap the shaft out of the centre unit with a rubber hammer.

    #1 Vova, Jun 23, 2008
    Last edited: Sep 2, 2008
  2. Vova

    Vova Member

    Apr 28, 2008
    Likes Received:
    Step 5: Getting more closely to the core...

    Now the wheel is off, you will see another snap ring, remove it but watch out it doesn't jump out and flies into an innocent onlookers face, who benches 200lbs and has a temper.

    (The top plate (which I will refer to in Step 7) in the first pic, its after mounting the new one, hence it looks shiny, in the 2nd pic the middle-thrust bearing is missing, dont mind it, its just to show the ring)



    Now, if you are lucky, the plate underneath will come off, if so, you can skip to step X. If not (like me) we will use another procedure, which you will probably have to and just follow the step-by-step guide.

    Step 6: Disassembling the exhaust side

    Now lets turn it around and start working the exhaust side. First thing to come out is a wannabe-snap-ring.This ring is double layered and is provided in the rebuild kit so not a problem if you bend it, however I still recommend to take it out carefully. This is to give you and impression of how it looks:


    You can screw it out and than take it out. Its fiddly but its do-able. Its the first to come out and last to go in on the exhaust side.


    Now there is a washer beneath it. Take it out as well.



    Now we can get to the bearings of the turbo. You can slide them out using something. I used these dental picking kind of tools.


    And its coming out...


    Here it is!

    #2 Vova, Jun 23, 2008
    Last edited: Jun 23, 2008
  3. Vova

    Vova Member

    Apr 28, 2008
    Likes Received:
    Now you have disassembled the exhaust side, the line-up should look like this, from left to right:

    - Exhaust wheel with shaft, with piston ring (more about that ring later)
    - Heatshield with some or allot of cooked oil
    - Spring-circli-double layer ring
    - Washer
    - Bearing
    (-optinal, circlip)


    On the inlet/compressor side, the line up should be:

    - Big snap ring (goes behind compressor housing but comes out first)
    - Compressor housing
    - Compressor wheel-nut
    - Compressor Wheel
    - O-ring
    - Small snap-ring


    Now we start working the inlet side again and try to get the top plate off in a rather unorthodox way but I couldn't find any other method.

    Step 7: Removing the top plate which should have come off in the perfect world...

    The "top plate" is the plate you see in beginning of Step 5 that comes behind the small snap ring. It should come off easy as the snap ring provides its tension but again, the perfect world story...mine didn't want to bodge a bit, tried everything ,even magnets and all and only had one more solution left:

    First of all, I do not advocate this way, however it was the only solution for me. I really hope you guys will be lucky and the plate comes off but if not, and there are no other means, you can try it this way. This will sound stupid and dangerous but its the only method I could think of, if somebody knows a better one, I'd like to hear it. However this method works and the turbo is still spinning at 100.000 without disintergrating, so here we go...

    When you look from the exhaust side:


    you can see the thrust bearing from behind which sits behind the top plate. Now by putting a sort of chisel, with not a sharp but a round flat side on top, in there so it sits against the thrust bearing, than by holding the compressor in your hands with the "chisel" under it, smack the chisel onto the workbench by pushing the compressor housing on top of it so to say, hard to explain. If you are lucky, the plate comes of because of the shock. If not (like me again..) it wont and you'll have to wack it harder, enough that the thrust bearing breaks off and pulls the plate up which results in this:

    The thrust bearing broke out of the collar and pushed the plate out, I darkened it as the flash was too bright, I have to start using the cam properly....


    If the top plate came off without the breaking stuff procedure, it should look like this:

    - Silver outer big part, is the thrust bearing which is responsible for not letting oil into the compressor, when it wears (the piston ring mainly), you get James Bond smokescreens on idle or gearshifts, which is why I went to rebuild the turbo.

    - Piston ring, hold the thrust bearing in its position. When you put the plate over it during assembly, you can hear it click when it snaps into place

    - 3 Torx screws that hold the thrust bearing to the collar.

    All the parts are provided in the rebuild kit.


    This is how it looks when dissassembled, the bearing is the goldish part in the middle, still inside:


    This is how the "assembly" looks back to front


    Step 8:Replacing the inlet-side stuff

    First to replace is another O-ring you can see here, note in this pic the shaft is still in while we already have removed it. The most middle round gold thing is the bearing. Note the slits, these match the slits on the back of the thrust collar, so make sure during reassembly you have the right way down/up.


    Than take out the bearing. Again, there will be a circlip behind it which you can replace but I didn't, so assuming you won't either. Now take the new bearing and compare it to your old one if its the same size, dip it in oil and put it back in.


    Now take the thrust collar and bearing. Put them into eachother and NOTE which side goes up, the oil passes in a sort of slit in it which maches in the centre catridge. The picture shows the collar from the top.



    Now take some Locktyte thread locking stuff and put it around the (new) Torx screws. However my kit already had some kit around the screw but for extra sureity I put on some of mine as well. Tighten the torx screws. Put the (new) piston ring around the thrust bearing.

    (Note the O-ring in this pic isn't replaced already like we did before, so think it out of the picture)


    Now put the new top plate over the thrust bearing and put it on good so it snaps into place. Than take your snap ring and put it GOOD, make sure its inside all the way.


    Well, the inlet side is done!!

    Step 9 :Replacing the exhaust side stuff

    Now below the bearing we have already taken out, is another circlip. Some people choose to replace them but I didn't. Why would I? The kit supplies them as well. Anyway, I just let them be and the turbo still works :smokin: . You can't really see it here but you will see it once the bearing is out.


    Anyway, take the new bearing, dip it in oil and place it back. (Note, picture shows old bearing)


    Take some time to clean the insides of sludge and other unwanted bodies

    #3 Vova, Jun 23, 2008
    Last edited: Jun 23, 2008
  4. Vova

    Vova Member

    Apr 28, 2008
    Likes Received:
    After the bearing, put back the washer as in the same order as removed:


    Than put back the stupid wannabe snap tension whatever it is-ring.


    Now putting it back is kinda bitchy but as the Zilvianet guid mentions, once you "get it" , it goes in, but as its auther, I also dicked around a good 30 minutes to get it in.

    The trick is, is not trying to screw it in from beginning but if I remember right, just put in and than screw the top "layer" over the ridge..I don't remember right as its a time ago but you'll figure it out.

    This piston ring, makes sure no oil passes down the exhaust and frequently wears out. Now take the exhaust wheel with the shaft (be carefull not to wipe out the marks you made on front and damge the wheel!) and remove the piston ring behind the turbine-wheel:


    I used a Snap-On piston ring remover, it pushes it out and than you just slide it out, handy materials to work with (thank you guy who let me use his tools in his friggin great overhaul shop!) if you have them.

    Clean the sludge/coocked oil and put in the new piston ring. Than put the shaft inside the centre housing again and push it in all the way so again it "clicks", snaps in.

    27.5.'re almost done! (and so am I writing this thing, damn, its 05:15 already!)

    Now take the compressor wheel and slide it over the shaft CAREFULLY, the blades are friggin butter.


    Now line up the marks like before, take the new nut and wind it on anticlockwise


    Now I took a torque wrench and put a 14mm on it, holding the exhaust side and tightening the nut with my other ratchet+socket. Setting the torque wrench to 20Nm. Well it was quite tight for a ~8mmish nut but the TW-didnt click, but I didn't take the rist and did it by feel.

    Well, you're done rebuilding the core! Don't forget the O-ring hasn't slipped off or something. However one important still is still to come.


    Now put the compressor housing back on CAREFULLYYYYY!!! I cannot stress this enough, I did it carefully and still managed to hit a blade, the tolerance is very small, took the compressor off and saw it was bent a tiniy winy litlle bit..I panicked, took the circlip pliers and bent it back ultra-carefull. Put the housing back on.

    Now another very important thing. Listen good.

    The big fat strong snap-ring has to go back on now. Now do this good. The ring, has to go in all the way "inside" the compressor housing. Best to do with 2 people, the ring is just very strong. The comp.-housing has to go on all the way. Now when you release the snap ring, make really sure it inside the comp housing, behind the ridge. Tap it with a hammer and chisel to be sure its in all around.

    Why do I stress this so much? Well boys and girls, I put my snap ring on by myself and 20km later after driving a hose came off. I was putting it on and felt some play in the comp housing back and forth. To cut the story short, the snap ring wasnt IN all the way, it was 0.3mm on the ridge, you could even turn the comp-housing with 'some' force! Not good! Luckily the blades didn't hit it..however unluckily, I had to take the whole fuqing turbo off again just for this bloody ring.

    Allright, everything is done and bolted up. The shaft should have no play, 0.1-.2 mm at most, it must feel like new. However, it will not turn ultrasmooth like a new turbo..yet. Why? This is my theory; the old shaft has worn itself IN on the old bearings. The shaft is ultra hard forged steel, the bearings are buttery soft material, the shaft wears into them. Now the new bearings are perfectly surfaced but the shaft has height differences. If you feel with your nail over the shaft while its out, you can feel them. Anyway, the shaft has to "run in", wear in, into the new bearings and this happens in the first boosted run.

    I was a bit worried about this as well, it turned smooth allright but it didn't spin after release like a new turbo. Anyway, I put oil into the drain hole when mountin the turbo. When all was mounted up (don't forget to bleed the cooling system of the car ppl!) I too the fuel pump fuse out and let the car turn around on the starter to build up oil pressure and see if oil was coming out of the return hose. It did :) .

    / and now, I'm going to sleep, the How-To is 95% finished, the sun is already up and I havn't slept in ages, will correct all spelling and grammar erros this week and add the remaning 5%.

    #4 Vova, Jun 23, 2008
    Last edited: Jun 23, 2008
  5. NORFY

    NORFY Active Member

    May 31, 2008
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    good thread man, well done
  6. ringer

    ringer HOOooo!

    Oct 1, 2005
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    Good stuff! Sticky!!
  7. GmasterT

    GmasterT Heavy Industries...

    Nov 21, 2004
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  8. Vova

    Vova Member

    Apr 28, 2008
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    Bad news I'm afraid, the turbo, after 400KM just developed some play and started whistling, probably the blades scraping the compressor housing. The shaft has play, too much and way more than it had after the rebuild.

    /Edit: The play is 'ok' and has allowed the turbo to work for another 900KM, however now it smokes. The whistling sounds were because the compressor housing had play due to the snap ring coming out of its bedding a bit which I bodged a bit now and it has been fine.

    What caused it?

    See post below.
    #8 Vova, Jun 30, 2008
    Last edited: Sep 1, 2008
  9. Vova

    Vova Member

    Apr 28, 2008
    Likes Received:
    I'm quite sure I figured out why the turbo developed play. It wasn't any of the 3 mentioned above. It was lack of oil, 90% sure, here's why:

    It was lack of oil because of a the rear-camcover-seal leaking. I figured it out while just thinking what had all happend before. The thing was, that after I rebuilt the turbo, the car had been standing still for about 2 months, so the already leaking cam-cover-half-moon in the back probably dried and harded out and sealed worse.

    I remember I went for the 3rd testdrive after about 300miles doing mountain runs all night long, boosting and getting the oil to around 100c. Than I came home, looked around the engine for oil or water leaks and noticed the cam cover had leaked quite severe! Than checked oil in sump and it was júst above minimum!!! I quickly added about .5 L, don't remember exactly, I was panicking to get the oil to level again, lol. After adding that, it was full again.

    Than another 100 miles went by and thats when I started hearing, or maybe only than noticing, that some kind of sound is coming from the turbo.

    With the "broken" turbo, I did another test run yesterday to see what it'll do and its still "working" and has for about 30miles! I think this indicates that it does have more play but now that its properly oil fed, its working and not going worse in a rapid time. However I still think its too late and I'll be replacing it with a GT28R as the blades are scuffed and I don't want to bother rebuilding it again as the car needs to endure a 6H race in September.

    So not to cover my How-To but I'm honestly convinced the process is fine and that it was the lack of oil that made the shaft have play, not something else.

    It is also quite frequently occuring that the turbo is the first to suffer when a lack of oil occurs, than the BE's (Thank christ I spotted it just in time!).

    Why not these other possibilities, well here's why I think why:

    #1 Oil feed

    Got it out, checked, blew thru it, sent oil under pressure thru it, all fine, not to blame.

    #2 Not rebalancing

    It ran for 400miles, if the balance was so far off it would have gone long ago. I mean come'on, the thing span for minutes at 100k RPM during that period.


    Same as #2, worked fine for too long.
    #9 Vova, Jul 10, 2008
    Last edited: Sep 1, 2008
  10. Vova

    Vova Member

    Apr 28, 2008
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    As per edited post 1, the turbo has been doing its job for about 1200km pretty well but started smoking again. Shaft play is 'ok' .

    Conclusion: not worth rebuilding, just buy a new one!
  11. Chuki

    Chuki Member

    Oct 4, 2006
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    well done thanks for the experience vova
    but does anybody know were to buy a NEW T28 (S14) with journal bearing???
  12. Vova

    Vova Member

    Apr 28, 2008
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    At the stealer :-D , why bother man, just get a GT28R, they aint that expensive from the states with the € vs. $.
  13. djmickey11

    djmickey11 New Member

    Jul 28, 2008
    Likes Received:
    hi does any one have spare wastgate for sale

    any spare turbo westgate around for a t28 plusar turbo for sale as mine is crack please msg me regards
  14. Vova

    Vova Member

    Apr 28, 2008
    Likes Received:
    How big is the crack? I have ran 2 turbo's with cracked exhaust housings and it has never been an issue, they all seem too. As longs as its not 'cracked open'.

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