Turbo diagnosis (with pics)

[cwspellowe]

Right started a new thread as this will contain a lot of information. Hoping those more experienced than me with turbo stresses will be able to contribute.

Turns out the turbo shat itself, shaft snapped clean in two and the turbine wheel and half the shaft are somewhere down the motorway as they're not in the exhaust anywhere. Oh dear.

Right here's what i'm faced with. We'll start compressor side seen as that's the only side of the turbo left

One bent shaft and trimmed compressor wheel anyone?



And for Ruan, shaft size is roughly 4.5mm



Shaft seems to have snapped in a concave conical shape, doesn't look twisted from what I can see. Pretty sure it's a solid shaft so not sure why it looks like this







More of the compressor side and internals







This little bugger's taken a bit of a beating







And towards the hotside



Finally some sizes of various pieces. Ruan said over whatsapp he was interested to know a few dimensions.

Oil drain diameter ~12mm



Inlet size ~49mm



T2 manifold port size ~46mm



Turbine inlet size ~36mm



As you can see here, there's a good 5mm or so ring of coke around the turbine inlet, indicating the T2 mani outlet is much larger. Could possibly have been a factor, accelerating gas flow in the turbo. Seems strange the turbine inlet on both GT2056's have been like this.



Also for comparison, the castings and serial numbers are different on the two compressor housings, for what SHOULD have been the same turbo. Curious.

First the original GT2056 that I killed by not bolting the compressor housing down properly





Also looks to me like it says the A/R is 0.53 on this. And another casting next to the .53 that says either 06 or 90, not sure what this is for.

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And the second GT that i've just removed





And again, 0.53A/R but 80 or 08 in the casting next to it, along with different serial numbers.

If anyone can tell me what's wrong and why it died please do enlighten me. The way it's snapped, tells me it probably isn't shrapnel damage, but it doesn't look to have snapped under torsional load either, the shaft is still straight.

One theory me and Ruan considered was that the hotside was in fact too small and the pressure ratio to the compressor side is what snapped the shaft, but again isn't consistent with the damage. The power band for a Vivaro/Movano/whatever is only up to about 3.5krpm tops so me taking it up to 5krpm at much higher flow than it's application COULD be what killed it. The compressor maps seem to indicated it SHOULD be ok with that flow though. My concern is the inlet to the turbine housing being so small even compared to a T2 mani.

There's no coking or scoring of the bearing, it still looks in decent nick and certainly hasn't starved of oil. There was shrapnel in the CHRA housing but tbh that could have been anything, including the shaft/wheels grinding themselves away when failing, so that's inconclusive.

Oil and filter were changed after the last failure, intercooler and pipes were flushed too. Don't think anything was left in the oil that could have damaged any seals but you never know.