Rebuilding Turbos

Discussion in 'Z32 Technical' started by Shane001, Aug 5, 2018.

  1. Shane001

    Shane001 Well-Known Member

    Messages:
    2,532
    Likes Received:
    35
    Trophy Points:
    48
    Checking a few things on the racecar this afternoon, and noticed the passenger side exhaust housing was wet with oil :(

    Couldn't see anywhere it was leaking from other than the turbo itself, so wiped it up as much as I could, then ran the car for a bit and sure enough, was a drip of oil at the bottom of the exhaust housing again. Looks like it's seeping down between the housing and the bolt plates.

    So I guess this means the rear seal is gone :(

    Had a look online, a few videos on pulling these apart and rebuilding them. Haven't had a good look yet. But looks like you can buy full bearing/seal kits for them. Mine are high flowed though so not sure if that means bearings and seals will be different.

    Anyone had a go at rebuilding these themselves?
    I can't afford to be paying for turbo rebuilds atm. Pretty much would rule me out of Bathurst next year :(
     
  2. IB

    IB ?????

    Messages:
    2,426
    Likes Received:
    26
    Trophy Points:
    48
    Zcar91 & I have rebuilt a couple of pairs of stock turbos. Only one pair in use so far and only a couple of thousand one.

    You need some good circlip pliers, including a big pair that lock for the inlet housing. We turned a pair of needle nose pliers into long thin circlip pliers for the small internal circlips.

    Any markings you make to re-align rotating assembly need to survive cleaning.

    Good luck.
     
  3. Shane001

    Shane001 Well-Known Member

    Messages:
    2,532
    Likes Received:
    35
    Trophy Points:
    48
    Thanks Ian. There's a couple of videos online, including of the 300ZX turbo's, dismantling and rebuilding them. Doesn't look too hard, attention to detail and put them back together exactly as they came apart and it should be doable.

    It's strange though where the oil is leaking. I would have though the oil would leak into the housing and burn out the exhaust, not seep out where the housing joins the core. And I haven't noticed any significant smoke out the exhausts including the last time out on track.
     
  4. Madcow

    Madcow Active Member

    Messages:
    3,256
    Likes Received:
    15
    Trophy Points:
    38
  5. Shane001

    Shane001 Well-Known Member

    Messages:
    2,532
    Likes Received:
    35
    Trophy Points:
    48
    Interesting, surprised no one has thought of this before.

    Our turbos are journal bearing though (don't know why but I always thought they were ball bearing), and I'm still running the factory oil cooler bypass setup, so they're only seeing 55ish psi max anyway. For anyone running full flow this would be a good idea though.
     
  6. RynoDrifterZ

    RynoDrifterZ Member

    Messages:
    58
    Likes Received:
    0
    Trophy Points:
    6
    Location:
    Sydney
    On the topic of rebuilding turbos, I have purchased a pair of hi flow turbos and have been told they could do with a rebuild, they’re gt2871r cores. If someone wants to do the rebuild for me and I can buy the kit
     
  7. Shane001

    Shane001 Well-Known Member

    Messages:
    2,532
    Likes Received:
    35
    Trophy Points:
    48
    Removed the dump pipe this afternoon, perfectly dry and clean all the way down the dumps, into the test pipes, and the exhaust housing. No signs of oil. Also can't feel any forward/rearward movement on the shaft.

    I would think if the exhaust seal was leaking there would be signs of oil in the exhaust housing correct?

    So I'm hoping it's not the turbo internals, so that leaves the oil feed pipe on the top of the turbo. Either way it's engine out as there's no way to get to it with the engine in. Hopefully that's all it is and I don't have to do a turbo rebuild.
     
    Hellsheep likes this.
  8. IB

    IB ?????

    Messages:
    2,426
    Likes Received:
    26
    Trophy Points:
    48
    I would have thought you could get to the passenger side turbo oil flare but without pulling the engine. You'd need to remove a few things that you'd have to remove to pull the engine, so no great loss in trying. You might need to modify a spanner.
     
  9. Shane001

    Shane001 Well-Known Member

    Messages:
    2,532
    Likes Received:
    35
    Trophy Points:
    48
    A couple of the new coolant hoses on the rear of the engine still have a slight leak, so need to pull the engine anyway, going to RTV the ****ers! Plus I've had the engine out so many times this year now it's almost second nature lol.

    But will have a closer look when I get to this. Currently working on suspension upgrades.

    What are peoples thoughts on my diagnosis that it's unlikely to be the rear turbo seal? If this was leaking would you generally expect to see oil residue in the turbine housing and dump pipes?
     
  10. Martin Williams

    Martin Williams Active Member

    Messages:
    1,366
    Likes Received:
    11
    Trophy Points:
    38
    I agree with you. In my experience the first sign that the turbo seal is leaking is smoke from the exhaust on start-up or idle. To have a bad enough seal leak to show up on outside of exhaust housing I would expect to see some oil residue in turbine housing or blue smoke from exhaust. More like to be a crack in oil inlet flare or pipe.
     
  11. Shane001

    Shane001 Well-Known Member

    Messages:
    2,532
    Likes Received:
    35
    Trophy Points:
    48
    Thanks Martin, that's what I figured. Big sigh of relief not having to rebuild the turbos.
     
  12. Shane001

    Shane001 Well-Known Member

    Messages:
    2,532
    Likes Received:
    35
    Trophy Points:
    48
    So pulled the engine last weekend, had a good look over the engine yesterday, can't see anywhere external that the oil is leaking from, no where is wet. Had a closer look with a torch inside the back of the turbo, shining past the turbine wheel, and it is wet in behind the wheel. So looks like it is the seal.

    For now I'm just going to put it back in and run it as is. Can't afford a rebuild at the moment and don't have time to do it myself. May look at hiflowing my other set (though they're auto turbos) or keep an eye out for a replacement.

    There is no noticeable front/rear shaft movement, and they don't seem to be leaking very much, not even enough to have noticed out the exhaust as per usual symptoms. If they get to the point they are blowing smoke out the exhaust or leaking badly externally then I'll deal with it then. I did tighten the housing bolts, they weren't loose maybe wrist tight.

    Any reasons why this is a really bad idea? (lol)

    I guess I should be looking into a cross pipe for the exhaust? I'll be removing the rear mufflers soon (sick of having the quietest race car every time I go out lol) so I can't see this as being a big issue for the seals being I will have next to no back pressure?
     
  13. stumagoo

    stumagoo Active Member

    Messages:
    2,083
    Likes Received:
    14
    Trophy Points:
    38
    mine weep very slightly when the turbo is cold - when its hot the seal seems to stop and all the smoke goes away (once whatever was in the exhaust is burnt away)
     
    pmac likes this.
  14. pmac

    pmac Z,, IT'S COMPLICATED!!!!!

    Messages:
    296
    Likes Received:
    8
    Trophy Points:
    18
    I agree with Stu and Martin.
    Journal bearing turbos are sealed with steel rings that look like piston rings. They are not at perfect seal and work on clearance rather than a complete seal, a small amount of oil can leak past them when the car is sitting.
    Despite what people say the drivers side turbo can be removed with the engine in. Mind you these are T25's and did not have all the heat shields thst the standard set up has.

    https://photos.app.goo.gl/awNEpQsEcUigWGrv6

    Have a look on that link for photos. The modified ring spanner is essential.
    On the first atempt I seperated the turbo into 2 halves, this was not necessary. Remove the dump and seperate it at the manifold joint, the worst job was the prying back the locking tabs for the manifold nuts.
    Rebuilding the turbos is a piece of cake compared removing them.

    [​IMG]
     
  15. Shane001

    Shane001 Well-Known Member

    Messages:
    2,532
    Likes Received:
    35
    Trophy Points:
    48
    Bugger that lol! I'm becoming an old hand at removing these engines :) I think 3 times this year now, just dropped it back in again this afternoon. Most time consuming part is disconnecting everything and connecting it back up again.

    Thanks everyone for your feedback and advice. I'm going to leave it as is for now and see how it goes at the next track day.

    PMAC I wouldn't be surprised if the seal was installed with the gap at the bottom! Other than this apparent leak the turbos appear to be in very good condition. I don't know how long before I got the car that they were rebuilt, but I know they hardly had any work prior to me buying it, as all the leaks were limiting boost to only a few psi lol.
     
    pmac likes this.

Share This Page